3B2 E2.5 C11 Review
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Questions and Answers

What is the main function of an automatic expansion valve?

  • Regulate the temperature in the refrigerated space
  • Increase the pressure within the condenser
  • Control the speed of the compressor
  • Maintain a constant pressure within the evaporator (correct)

    • Which component pushes the valve open in an automatic expansion valve?

  • Opening spring (correct)
  • Closing spring
  • Equalizer connection
  • Valve push rod

    • What happens to the automatic expansion valve when the compressor stops?

  • It increases the pressure in the condenser
  • It closes (correct)
  • It opens wider
  • It regulates the temperature

    • How does the evaporator pressure affect the diaphragm in an automatic expansion valve?

    <p>Pushes it upwards</p> Signup and view all the answers

    Which component of the automatic expansion valve assists in adjusting the desired evaporator pressure during operation?

    <p>Opening spring</p> Signup and view all the answers

    What action does the increased evaporator pressure cause in an automatic expansion valve?

    <p>Closes the valve</p> Signup and view all the answers

    What is the purpose of the capillary tube in the refrigerating system?

    <p>To equalize the high and low-pressure sections of the system</p> Signup and view all the answers

    What type of condensers are more efficient and commonly used in refrigerating systems?

    <p>Water-cooled</p> Signup and view all the answers

    What happens to the solenoid coil when the compressor stops?

    <p>The power supply is cut off</p> Signup and view all the answers

    What is the function of the bellows in the pressure-operated throttling valve?

    <p>To open the valve</p> Signup and view all the answers

    What is the purpose of controlling the flow of cooling water through the condenser?

    <p>To reduce water wasting</p> Signup and view all the answers

    What happens to the valve plunger when the compressor starts?

    <p>It moves up into the center of the coil</p> Signup and view all the answers

    What is the primary function of the heat exchanger in the refrigeration system?

    <p>It decreases the temperature of the liquid refrigerant.</p> Signup and view all the answers

    How is refrigeration control achieved by regulating the output of the compressor?

    <p>By varying the output of the compressor through speed adjustment or unloaders.</p> Signup and view all the answers

    What metals are typically used in a bimetallic strip for a direct temperature control?

    <p>Invar and brass or Invar and steel.</p> Signup and view all the answers

    What causes the bending action in a bimetallic strip?

    <p>The change in the length of the Invar per degree of temperature change will always be less than that of the brass or steel.</p> Signup and view all the answers

    How does a pressure-actuated control operate the compressor?

    <p>By using a low-pressure bellows connected to the evaporator outlet piping.</p> Signup and view all the answers

    What type of control cannot be used in conjunction with an automatic expansion valve refrigerant control?

    <p>A pressure-actuated control.</p> Signup and view all the answers

    How does a refrigerant control achieve regulation of the flow of refrigerant to the evaporator?

    <p>By varying the output of the compressor.</p> Signup and view all the answers

    What causes the bellows or diaphragm to move in an indirect temperature control?

    <p>Changes in temperature that change the pressure exerted by the fluid in the bulb.</p> Signup and view all the answers

    What causes the bi-metal type temperature sensing element to bend in the direction of the Invar?

    <p>Increasing the temperature of the bimetallic strip.</p> Signup and view all the answers

    What is the primary function of a thermostat in a refrigeration system?

    <p>It opens or closes an electric circuit to start or stop the compressor.</p> Signup and view all the answers

    What is the purpose of the thermostatic expansion valve?

    <p>To regulate the flow of refrigerant to the evaporator based on temperature</p> Signup and view all the answers

    What happens to the valve in a thermostatic expansion valve when there is too much refrigerant flowing to the evaporator?

    <p>It tends to close to reduce the flow of refrigerant</p> Signup and view all the answers

    What type of valve is used to maintain the liquid refrigerant level in a flooded evaporator?

    <p>Low side float valve</p> Signup and view all the answers

    What is the purpose of the capillary tube in a thermostatic expansion valve?

    <p>To connect the diaphragm to the bulb</p> Signup and view all the answers

    What happens when the temperature in the refrigerated space rises in a system with an automatic expansion valve?

    <p>The compressor is started and the valve opens</p> Signup and view all the answers

    What is the function of the bulb in a thermostatic expansion valve?

    <p>To measure the temperature of the refrigerant</p> Signup and view all the answers

    What is the difference between a low side float valve and a high side float valve?

    <p>Location in the system</p> Signup and view all the answers

    What happens to the valve in a thermostatic expansion valve when the superheat of the vapour is high?

    <p>It opens further to allow more refrigerant to enter the evaporator</p> Signup and view all the answers

    What is the function of the diaphragm in a thermostatic expansion valve?

    <p>To regulate the flow of refrigerant to the evaporator</p> Signup and view all the answers

    What mechanism in the automatic expansion valve ensures that it maintains a constant pressure within the evaporator when the compressor is operating?

    <p>The opening spring</p> Signup and view all the answers

    What is the primary function of the thermostatic switch in the refrigeration system with an automatic expansion valve?

    <p>To stop the compressor when the temperature in the refrigerated space drops</p> Signup and view all the answers

    What component in the automatic expansion valve directly affects the desired evaporator pressure during operation?

    <p>The opening spring</p> Signup and view all the answers

    Which component in the automatic expansion valve assists in the valve closing action when there is excessive refrigerant flow to the evaporator?

    <p>The closing spring</p> Signup and view all the answers

    What causes the automatic expansion valve to close when the compressor stops?

    <p>The increased evaporator pressure</p> Signup and view all the answers

    Which component in the automatic expansion valve is responsible for preventing the valve from opening too wide during operation?

    <p>The opening spring</p> Signup and view all the answers

    What type of expansion valve is not directly affected by the evaporator pressure?

    <p>Low side float valve</p> Signup and view all the answers

    Which expansion valve operates by maintaining a constant liquid level in its own float chamber?

    <p>High side float valve</p> Signup and view all the answers

    What type of expansion valve has a bellows component instead of a diaphragm chamber?

    <p>Bellows type thermostatic expansion valve</p> Signup and view all the answers

    Which element in the thermostatic expansion valve is exposed to evaporator pressure and located in the low-pressure side of the system?

    <p>Bulb</p> Signup and view all the answers

    What component in the automatic expansion valve directly assists in adjusting the desired evaporator pressure during operation?

    <p>Spring</p> Signup and view all the answers

    Which expansion valve regulates the flow of refrigerant into the evaporator by maintaining a constant liquid level in the surge drum or accumulator?

    <p>Low side float valve</p> Signup and view all the answers

    What component in the thermostatic expansion valve senses temperature changes and regulates the flow of refrigerant based on superheat?

    <p>Bulb</p> Signup and view all the answers

    Which expansion valve is directly affected by the forces tending to close the valve, such as evaporator pressure and the force of the spring?

    <p>Thermostatic expansion valve</p> Signup and view all the answers

    What type of control cannot be used in conjunction with an automatic expansion valve refrigerant control, as they are two separate and distinct controls?

    <p>Pressure-actuated control</p> Signup and view all the answers

    Which expansion valve functions to maintain a constant level in the float chamber, and more liquid refrigerant will flow to the float chamber if the rate of vaporization in the evaporator increases?

    <p>High side float valve</p> Signup and view all the answers

    What is the primary function of a pressure-actuated control in a refrigeration system?

    <p>To start and stop the compressor based on evaporator pressure changes</p> Signup and view all the answers

    What is a significant limitation of using a pressure-actuated control for the compressor?

    <p>It is not effective with automatic expansion valve refrigerant control</p> Signup and view all the answers

    Which temperature-sensing element is not affected by moisture or vibration?

    <p>Resistive temperature-sensing element</p> Signup and view all the answers

    Which method of refrigeration control involves varying the output of the compressor?

    <p>All of the above</p> Signup and view all the answers

    What causes the bellows or diaphragm to move in an indirect temperature control?

    <p>Changes in the pressure exerted by the fluid in the bulb</p> Signup and view all the answers

    Which thermostat uses a bimetallic strip made up of Invar and brass or steel?

    <p>Direct temperature control thermostat</p> Signup and view all the answers

    What are the primary components of a thermostatic expansion valve?

    <p>Bulb, diaphragm, valve, and spring</p> Signup and view all the answers

    What is the main purpose of the bellows in a pressure-operated throttling valve?

    <p>To expand and contract based on pressure changes in the evaporator outlet piping</p> Signup and view all the answers

    Which type of refrigerant control system is not suitable for use with a capillary tube?

    <p>Automatic expansion valve control system</p> Signup and view all the answers

    What happens to the solenoid coil when the compressor stops in a thermostatic expansion valve system?

    <p>It loses power, causing the valve to close</p> Signup and view all the answers

    What is the main function of a high-pressure control in a refrigeration system?

    <p>To prevent possible damage to the equipment by stopping the compressor when the pressure on the high-pressure side becomes excessive</p> Signup and view all the answers

    What purpose do high-pressure controls with 'lock-out' devices serve?

    <p>Prevent the compressor from starting automatically after a shutdown</p> Signup and view all the answers

    Why are pressure-limiting devices necessary for systems containing more than 9 kg of refrigerant and operating above atmospheric pressure, according to CSA B52?

    <p>To stop the action of the compressor or generator at a pressure less than 90% of the pressure relief valve setting</p> Signup and view all the answers

    Where should pressure-limiting devices be connected in a refrigeration system, as per CSA B52?

    <p>Between the compressor and the discharge side stop valve</p> Signup and view all the answers

    What is a significant limitation of using a pressure-actuated control for the compressor?

    <p>Its inability to adapt to changing temperature requirements</p> Signup and view all the answers

    What is the purpose of the capillary tube in a thermostatic expansion valve?

    <p>To sense the evaporator's temperature and regulate the flow of refrigerant</p> Signup and view all the answers

    What is the primary difference between a relief valve and a rupture disc in a refrigerating system?

    <p>A relief valve reseals itself when the pressure drops to a safe limit, while a rupture disc does not.</p> Signup and view all the answers

    What is the function of the fusible plug in a refrigerating system?

    <p>To release refrigerant when the saturation pressure reaches a certain value.</p> Signup and view all the answers

    What is the main advantage of using a rupture disc in a refrigerating system?

    <p>It can burst at a lower pressure than a relief valve.</p> Signup and view all the answers

    How does a pressure relief valve function in a refrigerating system?

    <p>It opens and discharges refrigerant if the pressure exceeds the set value.</p> Signup and view all the answers

    What is the role of a rupture member in a refrigerating system?

    <p>It bursts before the pressure in the system reaches a dangerous level.</p> Signup and view all the answers

    What happens to a relief valve when the pressure drops to a safe limit?

    <p>It closes.</p> Signup and view all the answers

    What is the purpose of the oil pressure failure switch in a refrigeration compressor?

    <p>To shut down the compressor when the oil pressure drops below the safe minimum limit for a predetermined period</p> Signup and view all the answers

    What is the function of the differential pressure switch in the oil pressure failure switch?

    <p>To compare the oil pump discharge pressure and the suction pressure</p> Signup and view all the answers

    What is the purpose of the timer switch in the oil pressure failure switch?

    <p>To allow the compressor to operate for a short time to establish the required oil pressure differential</p> Signup and view all the answers

    What happens to the compressor motor when the oil pressure failure switch detects a low oil pressure?

    <p>It is shut down after a short delay</p> Signup and view all the answers

    What is the purpose of the pressure-relief device in a refrigeration system?

    <p>To relieve pressure due to fire or other abnormal conditions</p> Signup and view all the answers

    What is the requirement for the installation of pressure-relief devices according to CSA B52?

    <p>They should be connected directly to the pressure vessel or other parts of the system protected</p> Signup and view all the answers

    What is the purpose of the crankcase or housing in a refrigeration compressor?

    <p>To subject the oil pump to suction pressure</p> Signup and view all the answers

    What happens to the timed switch in the oil pressure failure switch when the oil pressure differential does not build to the cut-in point within a preset time?

    <p>It gets energized</p> Signup and view all the answers

    What is the purpose of the heater circuit in the oil pressure failure switch?

    <p>To heat the bimetal strip</p> Signup and view all the answers

    What is the primary purpose of high-pressure controls in a refrigeration system?

    <p>To stop the compressor if the high-pressure side pressure becomes excessive</p> Signup and view all the answers

    Why are 'lock-out' devices on high-pressure controls considered essential for systems with water-cooled condensers?

    <p>To avoid equipment damage due to water supply failure</p> Signup and view all the answers

    According to CSA B52, what triggers the action of pressure-limiting devices on refrigeration systems?

    <p>90% of the pressure-relief valve setting</p> Signup and view all the answers

    Why are pressure-limiting devices necessary for systems containing more than 9 kg of refrigerant and operating above atmospheric pressure?

    <p>To prevent excessive pressure in the system</p> Signup and view all the answers

    How do pressure-limiting devices differ in their operation on water-cooled systems as opposed to other systems?

    <p>They must be reset manually after activation</p> Signup and view all the answers

    In a refrigeration system, what is the recommended location for pressure-limiting devices as per CSA B52?

    <p>Between the compressor and the discharge stop valve</p> Signup and view all the answers

    Why is it necessary to equip a refrigeration compressor with an oil pressure failure switch?

    <p>To prevent extensive damage caused by failure of the forced lubrication system</p> Signup and view all the answers

    What would cause the compressor motor to shut off in the oil pressure failure switch system?

    <p>The oil pump discharge pressure drops below the differential pressure switch cut-in point</p> Signup and view all the answers

    What is the primary purpose of the pressure relief devices in a refrigeration system according to CSA B52?

    <p>To prevent damage due to abnormal pressure conditions</p> Signup and view all the answers

    What action occurs if the oil pump discharge pressure drops below the cut-in point during compressor operation?

    <p>The differential pressure switch closes</p> Signup and view all the answers

    Why should pressure relief devices in a refrigeration system be directly pressure actuated?

    <p>To relieve pressure more efficiently during abnormal conditions</p> Signup and view all the answers

    How does the oil pressure failure switch in Figure 13 of the text primarily protect the refrigeration compressor?

    <p>By shutting down the compressor when oil pressure drops below a safe limit</p> Signup and view all the answers

    What happens when the energized heater circuit in the oil pressure failure switch activates?

    <p>The timer switch contacts close</p> Signup and view all the answers

    Why are stop valves prohibited between the pressure relief devices and the parts of the refrigeration system they protect?

    <p>To prevent overpressurization in the protected system parts</p> Signup and view all the answers

    In what scenario would a refrigeration compressor equipped with an oil pressure failure switch shutdown?

    <p>When the oil pressure drops below a safe minimum for a set period</p> Signup and view all the answers

    What is the main benefit of having pressure relief devices readily accessible for inspection and repair in a refrigeration system?

    <p>To enable quick intervention during abnormal conditions</p> Signup and view all the answers

    What is the purpose of a fusible plug in a refrigerating system?

    <p>To prevent over-pressure in the system</p> Signup and view all the answers

    What is the primary difference between a relief valve and a rupture disc?

    <p>Their function</p> Signup and view all the answers

    What happens to a relief valve when the pressure drops to a safe limit?

    <p>It closes</p> Signup and view all the answers

    Which of the following is NOT a pressure relief device?

    <p>Expansion valve</p> Signup and view all the answers

    What is the purpose of a pressure relief device in a refrigerating system?

    <p>To relieve pressure in the system</p> Signup and view all the answers

    What is the requirement for the installation of pressure-relief devices according to CSA B52?

    <p>On all refrigerating systems</p> Signup and view all the answers

    What effect does oil circulating with the refrigerant have on the condenser and evaporator tubes?

    <p>It forms a film on their surface, lowering their heat transfer capacity</p> Signup and view all the answers

    What happens to the oil problem in the evaporator as the evaporator temperature drops?

    <p>It becomes more severe</p> Signup and view all the answers

    What is the main function of an oil separator in a refrigeration system?

    <p>To prevent oil from carrying over to the condenser</p> Signup and view all the answers

    What principle of operation does the impingement type oil separator use?

    <p>Impingement</p> Signup and view all the answers

    What causes the velocity of the refrigerant vapour to be considerably reduced in an impingement type oil separator?

    <p>The larger area of the separator in relation to the inlet line</p> Signup and view all the answers

    Why does the oil problem become more severe in the evaporator as the temperature is reduced?

    <p>The oil becomes thicker as the temperature is reduced</p> Signup and view all the answers

    What is the purpose of the oil still incorporated into a refrigeration system?

    <p>To reduce refrigerant losses and make the drained oil easier to handle</p> Signup and view all the answers

    How does the oil and refrigerant mixture boil off in the oil still?

    <p>Very slowly under compressor suction pressure</p> Signup and view all the answers

    What happens if the drained oil in a refrigeration system appears discolored after standing in a pail?

    <p>A laboratory analysis should be done to determine reusability</p> Signup and view all the answers

    What should be done before starting to drain oil from different points in a refrigeration system?

    <p>Close the drain valve on the recovery drum or still</p> Signup and view all the answers

    What method is recommended to drain oil from an ammonia system without an integral oil recovery arrangement?

    <p>Extended drain pipes into a pail of water</p> Signup and view all the answers

    How is refrigerant separated from the remaining oil in the oil still?

    <p>By distillation process and gravity separation</p> Signup and view all the answers

    What should be done if the drained oil in a pail remains milky looking and floats on top of the water?

    <p>Analyzing with a laboratory test</p> Signup and view all the answers

    Why might the pressure relief device be necessary in a refrigeration system?

    <p>To handle pressure surges and prevent system damage</p> Signup and view all the answers

    What is the function of the oil return piping shown in Figure 19?

    <p>To facilitate oil drainage to the compressor</p> Signup and view all the answers

    What is the purpose of the recovery drum or still in a refrigeration system?

    <p>To minimize oil accumulation points</p> Signup and view all the answers

    What is the primary reason for the formation of a film on the surface of the condenser and evaporator tubes due to oil circulation?

    <p>Thickening of oil at low temperatures</p> Signup and view all the answers

    What is the primary function of an oil separator in a refrigeration system?

    <p>To separate oil from the refrigerant</p> Signup and view all the answers

    What is the result of higher discharge pressure in a refrigeration system due to oil circulation?

    <p>Increased power consumption by the compressor</p> Signup and view all the answers

    What is the principle behind the operation of a cyclone oil separator?

    <p>Centrifugal force</p> Signup and view all the answers

    What happens to the velocity of the refrigerant vapor in an impingement type oil separator?

    <p>It is considerably reduced</p> Signup and view all the answers

    What is the primary problem caused by oil in the evaporator?

    <p>Reduced heat transfer capacity</p> Signup and view all the answers

    What drives off any refrigerant that might be entrained with the oil drained from the oil separators, liquid receiver, coolers, and evaporator?

    <p>An oil still</p> Signup and view all the answers

    In which part of the oil still incorporated into a refrigeration system does the refrigerant vaporize and rise to the top?

    <p>At the top</p> Signup and view all the answers

    What happens if the drained oil from an ammonia system, when placed in a pail of water, remains milky looking after standing for some time?

    <p>It suggests the oil may not be suitable for re-use</p> Signup and view all the answers

    What is the purpose of the common oil receiver or recovery drum in a refrigeration system?

    <p>To drain multiple oil accumulation points</p> Signup and view all the answers

    What should be done before starting to drain the oil from a particular point in a refrigeration system?

    <p>Close the drain valve on the recovery drum</p> Signup and view all the answers

    What is the function of extending the drain pipe from each point in an ammonia system into a pail of water during oil draining?

    <p>To absorb any escaping ammonia fumes</p> Signup and view all the answers

    What action indicates that the oil has been drawn off completely and ammonia vapor is condensing during oil drainage from an ammonia system?

    <p>A cracking sound</p> Signup and view all the answers

    What should be done if the drained oil from a refrigeration system, when placed in water, appears milky and remains milky after some time?

    <p>Run a laboratory analysis on the oil</p> Signup and view all the answers

    What should be done if frost accumulation ceases during oil drainage from a refrigeration system?

    <p>Close the vapour valve between the drum and compressor suction</p> Signup and view all the answers

    Why might a refrigeration system operator choose to run a laboratory analysis on oil that appears milky after drainage?

    <p>To assess the oil's chemical composition</p> Signup and view all the answers

    What is a primary consequence of non-condensable gases in a refrigeration system?

    <p>Increase in compressor power consumption</p> Signup and view all the answers

    Where do most non-condensable gases tend to collect in a refrigeration system?

    <p>Top of the condenser</p> Signup and view all the answers

    What part of the refrigeration system would non-condensable gases NOT accumulate in?

    <p>Evaporator</p> Signup and view all the answers

    How can non-condensable gases be removed from a refrigeration system?

    <p>Purging</p> Signup and view all the answers

    Which component would be stressed more due to the presence of non-condensable gases in a refrigeration system?

    <p>Compressor valves</p> Signup and view all the answers

    What is the purpose of fitting some form of purge to the condenser and receiver in a refrigeration system?

    <p>To remove non-condensable gases</p> Signup and view all the answers

    What is the purpose of the non-condensable gas purge in a refrigeration system?

    <p>To remove non-condensable gases from the system</p> Signup and view all the answers

    What is the role of the expansion valve in the non-condensable gas purge process?

    <p>To admit liquid refrigerant into the coil</p> Signup and view all the answers

    How does the automatic purger work?

    <p>By using an inverted bucket that opens and closes the liquid supply valve</p> Signup and view all the answers

    What happens when the non-condensable gases and vapour leave the top of the purger in an automatic purger?

    <p>The liquid level drops</p> Signup and view all the answers

    What prevents refrigerant vapour from escaping with the non-condensable gases in the automatic purger?

    <p>The cooling action of refrigerant passing through the refrigeration coil</p> Signup and view all the answers

    What is the purpose of the inverted bucket in the automatic purger?

    <p>To open and close the liquid supply valve</p> Signup and view all the answers

    What causes the liquid level to drop in the automatic purger?

    <p>The displacement of the liquid by the non-condensable gases</p> Signup and view all the answers

    What is the result of higher discharge pressure in a refrigeration system due to oil circulation?

    <p>Decreased efficiency</p> Signup and view all the answers

    What is the purpose of a pressure relief device in a refrigerating system?

    <p>To protect the system from excessive pressure</p> Signup and view all the answers

    What is the primary function of the thermostatic switch in a refrigeration system with an automatic expansion valve?

    <p>To control the opening and closing of the valve</p> Signup and view all the answers

    What is the primary consequence of having non-condensable gases in a refrigeration system?

    <p>Higher discharge pressure and power consumption</p> Signup and view all the answers

    What is a common method to remove non-condensable gases from a refrigeration system?

    <p>Purging, either manually or automatically</p> Signup and view all the answers

    What are some potential causes of non-condensable gases in a refrigeration system?

    <p>Impurities in the refrigerant and breakdown of lubricating oil</p> Signup and view all the answers

    What is a typical location where non-condensable gases accumulate in a refrigeration system?

    <p>At the highest point of the condenser</p> Signup and view all the answers

    What are some consequences of non-condensable gases accumulating in the receiver of a refrigeration system?

    <p>Reduction of compressor capacity</p> Signup and view all the answers

    What is a disadvantage of manually purging non-condensable gases in a refrigeration system?

    <p>Does not remove all non-condensable gases</p> Signup and view all the answers

    What is the main purpose of the inverted bucket in the automatic purger?

    <p>To hold the non-condensable gases and vapour and close the liquid supply valve</p> Signup and view all the answers

    What happens to the valve plunger when the compressor starts?

    <p>It remains closed until the evaporator pressure builds up</p> Signup and view all the answers

    Which component of the automatic expansion valve assists in adjusting the desired evaporator pressure during operation?

    <p>The diaphragm</p> Signup and view all the answers

    What type of expansion valve is not directly affected by the evaporator pressure?

    <p>Electronic expansion valve</p> Signup and view all the answers

    What happens to the solenoid coil when the compressor stops?

    <p>It de-energizes immediately</p> Signup and view all the answers

    What type of control cannot be used in conjunction with an automatic expansion valve refrigerant control?

    <p>Capacity control</p> Signup and view all the answers

    What is the main function of a high-pressure control in a refrigeration system?

    <p>To protect the compressor from excessive pressure</p> Signup and view all the answers

    Which expansion valve regulates the flow of refrigerant into the evaporator by maintaining a constant liquid level in the surge drum or accumulator?

    <p>Float valve</p> Signup and view all the answers

    What is the primary purpose of high-pressure controls in a refrigeration system?

    <p>To protect the compressor from excessive pressure</p> Signup and view all the answers

    What is the primary function of a pressure-actuated control in a refrigeration system?

    <p>To regulate the flow of refrigerant to the evaporator</p> Signup and view all the answers

    What is the main difference between straight hydrocarbon refrigerants and ammonia in relation to moisture?

    <p>Ammonia absorbs more moisture than hydrocarbon refrigerants.</p> Signup and view all the answers

    What is the effect of the combination of water and ammonia in a refrigeration system?

    <p>Formation of aqueous ammonia that attacks nonferrous metals.</p> Signup and view all the answers

    In what specific scenario can corrosion occur in systems using halocarbon refrigerants?

    <p>When low-quality lubricating oils are used and discharge temperatures are high.</p> Signup and view all the answers

    What is the purpose of a dehydrator in a refrigeration system?

    <p>To absorb moisture and acid from the liquid refrigerant.</p> Signup and view all the answers

    What is the purpose of the drying agent in a dehydrator of a refrigeration system?

    <p>Absorb moisture and acid from the refrigerant.</p> Signup and view all the answers

    Why must the drying agent be periodically replaced in a dehydrator of a refrigeration system?

    <p>When it absorbs no more moisture.</p> Signup and view all the answers

    What is the primary effect of moisture in a refrigeration system?

    <p>It forms corrosive compounds that react with system materials.</p> Signup and view all the answers

    What happens when free water freezes in the refrigeration control?

    <p>The flow of refrigerant is prevented.</p> Signup and view all the answers

    What is the result of moisture mixing with refrigerants in a system?

    <p>It forms highly corrosive compounds.</p> Signup and view all the answers

    Why is it essential to maintain a low moisture level in a refrigeration system?

    <p>To prevent corrosion and damage to system components.</p> Signup and view all the answers

    What is the effect of moisture on the lubricating oil in a refrigeration system?

    <p>It deteriorates the oil and forms sludges.</p> Signup and view all the answers

    What is the primary consequence of moisture in a refrigeration system?

    <p>Corrosion and damage to system components.</p> Signup and view all the answers

    What corrosive compound is typically formed when moisture combines with common refrigerants?

    <p>Acids</p> Signup and view all the answers

    Which component is often affected by the formation of ice in the expansion valve?

    <p>Evaporator</p> Signup and view all the answers

    What is the primary reason for the variability in the minimum level of moisture that will produce harmful effects in a system?

    <p>All of the above</p> Signup and view all the answers

    What physical state can moisture exist in the refrigeration system?

    <p>Both liquid and solid</p> Signup and view all the answers

    What is the primary consequence of moisture corrosion in a refrigeration system?

    <p>Reduced equipment life</p> Signup and view all the answers

    Which component of the refrigeration system is likely to be affected by the clogging of valves and oil passages due to moisture?

    <p>Compressor</p> Signup and view all the answers

    What is a significant challenge in designing a refrigeration system using straight hydrocarbon refrigerants such as propane, ethane, and butane?

    <p>They absorb little to no moisture, causing free water to freeze in the refrigerant control and disrupt system operation.</p> Signup and view all the answers

    How does a pressure-relief device contribute to the overall safety of a large-capacity refrigeration system?

    <p>It protects the system from overpressure, which is a necessity for systems containing more than 9 kg of refrigerant and operating above atmospheric pressure.</p> Signup and view all the answers

    Which factor determines the effectiveness of a dehydrator in a refrigeration system?

    <p>The compatibility of the refrigerant with the drying agent in the dehydrator.</p> Signup and view all the answers

    What is the critical consequence of combining water and ammonia in a refrigeration system?

    <p>Formation of aqueous ammonia, a strong alkali that attacks nonferrous metals.</p> Signup and view all the answers

    How does the presence of high-quality lubricating oils impact corrosion in halocarbon refrigeration systems?

    <p>They aid in maintaining a low moisture level, reducing the risk of corrosion in the system.</p> Signup and view all the answers

    Which type of expansion valve is directly affected by the evaporator pressure during operation?

    <p>A thermostatic expansion valve, whose valve position is determined by the evaporator pressure and superheat.</p> Signup and view all the answers

    What is the purpose of admitting dry nitrogen gas after establishing a high vacuum in the system before adding refrigerant?

    <p>To remove moisture from the system</p> Signup and view all the answers

    What precaution should be taken when adding refrigerant in its gaseous state directly to the compressor?

    <p>Ensure no liquid refrigerant is carried over to the compressor</p> Signup and view all the answers

    Why is it necessary to wear goggles when handling refrigerants, even the 'safe' ones?

    <p>To protect against freezing of moisture in the eyes</p> Signup and view all the answers

    After adding the correct amount of refrigerant to the system, what should be done with the liquid charging valve and drum valve?

    <p>Close both the liquid charging valve and the drum valve</p> Signup and view all the answers

    Why should the refrigerant drum be inverted after connecting it to the liquid charging valve?

    <p>To purge any air from the charging line</p> Signup and view all the answers

    What is the role of the high vacuum produced in the system before adding refrigerant?

    <p>To remove moisture from the system</p> Signup and view all the answers

    Why is it important to disconnect the charging line carefully after the system has been operating for some time?

    <p>To avoid releasing refrigerant under pressure</p> Signup and view all the answers

    What is the purpose of turning on the condenser water supply during the refrigerant charging process?

    <p>To aid in cooling the refrigerant</p> Signup and view all the answers

    Why should the system compressor not be used when establishing a high vacuum in the system before adding refrigerant?

    <p>To prevent damage to the compressor valves</p> Signup and view all the answers

    How can the correct amount of refrigerant be determined during the charging period?

    <p>By weighing the refrigerant drum</p> Signup and view all the answers

    What is the recommended inert gas used for leak testing in refrigeration systems?

    <p>Oil-pumped dry nitrogen</p> Signup and view all the answers

    What should be removed before testing a refrigeration system with an inert gas?

    <p>Control and relief valves</p> Signup and view all the answers

    What should be shut before testing a refrigeration system with an inert gas?

    <p>Discharge and suction valves</p> Signup and view all the answers

    What is the purpose of the pressure-reducing valve or regulator in the nitrogen cylinder?

    <p>To reduce the pressure in the system</p> Signup and view all the answers

    Why should oxygen or flammable gases not be used for pressure testing?

    <p>Because they may cause explosions</p> Signup and view all the answers

    Where should the nitrogen cylinder be connected to the system?

    <p>Between the compressor discharge valve and the liquid line valve</p> Signup and view all the answers

    What is the purpose of using nitrogen during the pressure testing of a refrigeration system?

    <p>To provide a stable pressure while checking for leaks</p> Signup and view all the answers

    Which tool is used to detect halogen refrigerants in the system during leak testing?

    <p>Halide torch</p> Signup and view all the answers

    What is the main benefit of using an electronic leak detector during refrigeration system testing?

    <p>It can detect halogenated refrigerants</p> Signup and view all the answers

    Which step is required before starting the halogen refrigerant leak test procedure?

    <p>Charging the system with the appropriate halogen refrigerant</p> Signup and view all the answers

    When should the nitrogen cylinder be disconnected while performing a leak test using the halide torch?

    <p>Immediately after completing the 24-hour testing period</p> Signup and view all the answers

    What step is taken if no refrigerant leaks are found during the halide torch leak test?

    <p>Disconnect the nitrogen cylinder and let the system remain pressurized for 24 hours</p> Signup and view all the answers

    What happens if a technician forgets to turn off the nitrogen cylinder during a leak test?

    <p>The system will over-pressurize</p> Signup and view all the answers

    What process is used to detect halogen refrigerants during the halide torch leak test?

    <p>Reacting with a copper plate at the torch tip</p> Signup and view all the answers

    What information does the pressure gauge read when testing the high side of the system during pressure testing?

    <p>Required high side pressure</p> Signup and view all the answers

    What step should be taken before bleeding the nitrogen/refrigerant mixture from both sides of the system?

    <p>Repair any leaks that were discovered</p> Signup and view all the answers

    What is the primary purpose of using an inert gas in a refrigeration system leak test?

    <p>To pressurize the system before refrigerant charging</p> Signup and view all the answers

    Why is it essential to remove control and relief valves during inert gas testing?

    <p>To prevent damage from excessive pressure</p> Signup and view all the answers

    What is the primary benefit of using oil-pumped dry nitrogen as an inert gas for leak testing?

    <p>It removes moisture from the system</p> Signup and view all the answers

    What should be connected to the system during inert gas testing?

    <p>All of the above</p> Signup and view all the answers

    What is the purpose of the nitrogen cylinder's shut-off valve during inert gas testing?

    <p>To control the flow of nitrogen gas</p> Signup and view all the answers

    Why should oxygen or flammable gases not be used for pressure testing?

    <p>They can cause explosions</p> Signup and view all the answers

    What is the primary reason for producing a high vacuum in a refrigeration system before adding refrigerant?

    <p>To remove moisture and foreign materials from the system</p> Signup and view all the answers

    What is the purpose of cracking open the drum valve and allowing refrigerant gas to blow through the charging line?

    <p>To remove air from the charging line</p> Signup and view all the answers

    Why is it necessary to take precautions when disconnecting the charging line after the system has been operating for some time?

    <p>Because the line may contain some refrigerant under pressure</p> Signup and view all the answers

    What happens to the moisture in the system when a high vacuum is produced?

    <p>It is removed in vapour form</p> Signup and view all the answers

    What is the purpose of breaking the vacuum by admitting dry nitrogen gas?

    <p>To remove the last traces of moisture from the system</p> Signup and view all the answers

    What is the purpose of inverting the refrigerant drum during the charging process?

    <p>To allow refrigerant to flow slowly into the system</p> Signup and view all the answers

    Why is it important to wear goggles when handling refrigerants?

    <p>To protect the eyes from freezing due to moisture</p> Signup and view all the answers

    What is the purpose of opening the expansion valve during the refrigerant charging process?

    <p>To allow refrigerant to flow into the system</p> Signup and view all the answers

    What is the purpose of connecting the refrigerant drum to the liquid charging valve?

    <p>To add refrigerant to the system</p> Signup and view all the answers

    What is the purpose of setting the pressure reducing valve for the required low side pressure?

    <p>To ensure the system is at the required operating pressure</p> Signup and view all the answers

    What is the purpose of shutting off the expansion valve when testing the high side of the system?

    <p>To separate the high and low sides of the system</p> Signup and view all the answers

    What is the purpose of bleeding off the nitrogen from the high side using the bleed valve at the cylinder?

    <p>To ensure the system is depressurized</p> Signup and view all the answers

    What is the purpose of holding the free end of the rubber tube at the joint when using a halide torch leak detector?

    <p>To allow any leakage to flow up the tube and into the flame area</p> Signup and view all the answers

    What is the purpose of disconnecting the nitrogen cylinder when leaving the system unattended?

    <p>To prevent over-pressurization of the system</p> Signup and view all the answers

    What is the primary purpose of using a halide torch leak detector?

    <p>To detect halogen refrigerant leaks</p> Signup and view all the answers

    What is the purpose of using nitrogen during the pressure testing of a refrigeration system?

    <p>To pressurize the system to the required test pressure</p> Signup and view all the answers

    What should be done after the 24-hour period if there is no change in the system pressure during the halide torch leak test?

    <p>Bleed the nitrogen/refrigerant mixture from both sides of the system</p> Signup and view all the answers

    What is the purpose of the electronic leak detector?

    <p>To detect halogen refrigerant leaks</p> Signup and view all the answers

    At what concentration, by weight, does sodium chloride brine have its lowest freezing point of -21°C?

    <p>23%</p> Signup and view all the answers

    What is the lowest freezing point obtainable for calcium chloride and water brine?

    <p>-51°C</p> Signup and view all the answers

    How is the specific gravity of the brine determined when adding new brine to the system?

    <p>Using a hydrometer</p> Signup and view all the answers

    What is the minimum specific gravity of the brine required in the system?

    <p>1.2</p> Signup and view all the answers

    What is the purpose of the screen on the outlet connection from the brine-mixing tank?

    <p>To prevent solids from being drawn into the system</p> Signup and view all the answers

    Where do the brine lines from the brine-charging valve feed back into?

    <p>The top of the mixing tank</p> Signup and view all the answers

    What happens to the freezing point of brine when the salt concentration exceeds a certain point?

    <p>It increases</p> Signup and view all the answers

    What does a eutectic solution represent in a salt-water mixture?

    <p>The lowest freezing point</p> Signup and view all the answers

    What will happen if a brine mixture is too weak?

    <p>Excess water will precipitate</p> Signup and view all the answers

    How is a Salometer used in the context of brine control?

    <p>To determine the salt concentration in a solution</p> Signup and view all the answers

    What does the freezing temperature of a brine solution look like above and below the critical concentration for a eutectic solution?

    <p>It decreases below and increases above the critical concentration</p> Signup and view all the answers

    What is the role of a Salometer in the context of brine control?

    <p>To measure the percentage of salt in a solution</p> Signup and view all the answers

    What is the significance of a eutectic solution in brine control?

    <p>It has the lowest freezing point possible.</p> Signup and view all the answers

    How does the freezing temperature of brine change with salt concentration?

    <p>It first decreases and then increases beyond a certain salt concentration.</p> Signup and view all the answers

    What does the presence of excess water in brine result in?

    <p>Formation of ice crystals.</p> Signup and view all the answers

    How is a Salometer used in the context of brine control?

    <p>To indicate the eutectic solution concentration.</p> Signup and view all the answers

    What would happen if the brine solution is too strong?

    <p>Precipitation of salt crystals.</p> Signup and view all the answers

    In what scenario would the freezing temperature of the brine be above the eutectic temperature?

    <p>When the salt concentration is too high.</p> Signup and view all the answers

    What is the lowest freezing point obtainable for sodium chloride brine?

    <p>-21°C</p> Signup and view all the answers

    At what concentration does the lowest freezing point of calcium chloride and water brine occur?

    <p>29.87%</p> Signup and view all the answers

    What specific gravity should the brine have when the calcium chloride is added until the brine is sufficiently strengthened?

    <p>1.2</p> Signup and view all the answers

    Which part of the system is utilized to protect the outlet connection from drawing solids into the system?

    <p>Screen next to brine charging valve</p> Signup and view all the answers

    What should be done after the mixing tank is drawn down to facilitate adequate mixing of new brine with the old?

    <p>Close the main line valve</p> Signup and view all the answers

    What should be opened if the brine requires further strengthening after the initial mixing of the new brine with the old?

    <p>Brine charging valve on the pump discharge</p> Signup and view all the answers

    What is the requirement for emergency discharge systems in refrigerating plants with over 103 kPa designed for operation?

    <p>To be equipped with an emergency valve installed in a glass fronted box outside the building</p> Signup and view all the answers

    What must be tested and proved tight after complete installation and before operation in a refrigeration system?

    <p>Every refrigerant-containing part except specific components</p> Signup and view all the answers

    In case of emergency in a refrigerating plant, what is the purpose of the emergency discharge line placed above the roof set back from the edge?

    <p>To ensure the refrigerant is dispersed safely into the atmosphere</p> Signup and view all the answers

    What is the purpose of pressure-limiting devices on systems operating above atmospheric pressure?

    <p>To prevent overpressurization</p> Signup and view all the answers

    Which feature is NOT required by the special regulations for emergency discharge systems in refrigerating plants according to CSA B52?

    <p>A series of emergency valves between the discharge line and vessel</p> Signup and view all the answers

    Why is it important for the manually operated emergency valve to be installed on a horizontal pipe outside the building?

    <p>To ensure easy accessibility without interference from the building structure</p> Signup and view all the answers

    What is the maximum pressure setting of the pressure-limiting device on a system with a pressure relieving device?

    <p>Less than 90% of the high-side design pressure</p> Signup and view all the answers

    What is the purpose of painting the glass fronted box housing the emergency valve bright red?

    <p>To ensure the emergency valve is clearly visible outside the building</p> Signup and view all the answers

    Where should pressure-relief devices discharge in a refrigeration system?

    <p>To the outside of the building</p> Signup and view all the answers

    Which valves should not be located between the means of pressure relief and the part of the system being protected?

    <p>Stop valves</p> Signup and view all the answers

    What distance must be maintained from any openings like windows when placing the diffuser at the upper end of the emergency discharge line?

    <p>7.6 meters</p> Signup and view all the answers

    What are pressure-relief valves required to start functioning at?

    <p>Not exceeding the design pressure</p> Signup and view all the answers

    In what manner should pressure relief devices discharge, according to guidelines?

    <p>To the outside of the building</p> Signup and view all the answers

    Which part of the refrigeration system should be directly pressure actuated?

    <p>Pressure relief devices</p> Signup and view all the answers

    What is the primary material requirement for constructing the seats or discs of pressure-relief devices?

    <p>Refrigerant-resistant material</p> Signup and view all the answers

    At what pressure should all rupture members in a refrigeration system start to operate?

    <p>Not exceeding the design pressure</p> Signup and view all the answers

    What must be present on any enclosed space (cold-storage room) that is maintained by a refrigeration system at temperatures detrimental to health?

    <p>A suitable alarm system</p> Signup and view all the answers

    According to CSA B52, what protective measures are needed for enclosed spaces depending on local conditions?

    <p>Alarm system or second door/knockout panel</p> Signup and view all the answers

    What information is required by CSA B52 to be placed in a conspicuous location near the refrigerant compressors?

    <p>Emergency contact numbers</p> Signup and view all the answers

    What protective equipment must installation and service personnel have upon arriving at the premises of an ammonia refrigeration system?

    <p>Personal protective equipment required by jurisdiction</p> Signup and view all the answers

    Why does CSA B52 state that at least 10 liters of fresh water must be provided for every 1 kg of ammonia in the system?

    <p>To prevent freezing of discharged ammonia without salt or chemicals</p> Signup and view all the answers

    According to CSA B52, how should the discharge valve release ammonia when using the tank in the ammonia system?

    <p>Into the center of the tank near the bottom</p> Signup and view all the answers

    Why should the water used to absorb discharged ammonia in the tank not be prevented from freezing with salt or chemicals?

    <p>To minimize the risk of explosions</p> Signup and view all the answers

    What provision must a tank have when preventing the freezing of discharged ammonia in an alternative arrangement for pressure relief valve discharge?

    <p>A hinged cover or venting</p> Signup and view all the answers

    Why does CSA B52 permit an alternate arrangement for discharging pressure relief valves when the refrigerant is ammonia?

    <p>To prevent environmental pollution</p> Signup and view all the answers

    What provision must be made for relieving pressure vessels into the low side of a system according to CSA B52?

    <p>Sufficient capacity relief devices</p> Signup and view all the answers

    What is the minimum refrigerant quantity that would trigger the construction requirements for the emergency discharge line?

    <p>103 kg of Group A1 refrigerants</p> Signup and view all the answers

    What is the maximum pressure threshold above which systems require an emergency discharge valve?

    <p>103 kPa</p> Signup and view all the answers

    Where should the emergency valve be installed in a refrigeration plant according to regulations?

    <p>In a glass fronted box outside of the building</p> Signup and view all the answers

    What is the recommended distance required for placing the diffuser at the upper end of the emergency discharge line from any windows or openings?

    <p>7.6 m</p> Signup and view all the answers

    What key color should the glass fronted box containing the emergency valve be painted according to regulations?

    <p>Bright red</p> Signup and view all the answers

    Why is it important for the emergency discharge line not to have any valve between the emergency valve and the refrigerant storage vessel?

    <p>To allow for fast and unobstructed discharge in emergencies</p> Signup and view all the answers

    What should be the nominal-rated rupture pressure of rupture members used in lieu of, or in series with, a relief valve?

    <p>Greater than the design pressure of the protected parts of the system</p> Signup and view all the answers

    What must be the internal diameter of pressure vessels for a pressure relief device to be directly pressure actuated according to safety regulations?

    <p>Greater than 150 mm</p> Signup and view all the answers

    Where should pressure-relief valves discharge according to safety regulations for refrigeration systems?

    <p>To the outside of the building</p> Signup and view all the answers

    What material should the seats or discs of pressure-relief devices be constructed of in order to resist refrigerant corrosion?

    <p>Suitable material</p> Signup and view all the answers

    When may a pressure-limiting device be omitted on a system with less than 10 kg of Group A1 refrigerant according to regulations?

    <p>If it has been listed by an approved testing laboratory</p> Signup and view all the answers

    What is the maximum setting allowable for the pressure-limiting device on systems with no pressure relieving device?

    <p>Not exceeding 90% of the high-side design pressure</p> Signup and view all the answers

    In what condition must the pressure relief device protect a refrigeration system due to fire or other abnormal conditions?

    <p>When there is a pressure increase due to fire or other abnormal conditions</p> Signup and view all the answers

    What must the nominal-rated rupture pressure of any rupture members in a system be in relation to the design pressure?

    <p>Greater than the design pressure</p> Signup and view all the answers

    Where should fusible plugs and other pressure-relief devices be connected for effective operation?

    <p>Above the liquid refrigerant level</p> Signup and view all the answers

    What discharge location is permissible for pressure relief valves in refrigeration systems as long as they are not affected by back pressures?

    <p>High-side of the system</p> Signup and view all the answers

    What must be supplied for every 1 kg of ammonia in the system when using a water tank alternative arrangement for pressure relief valve discharge?

    <p>10 liters of fresh water</p> Signup and view all the answers

    According to CSA B52, what personal protective equipment must be provided for installation and service personnel working on a refrigeration system?

    <p>Equipment required by local jurisdiction</p> Signup and view all the answers

    For enclosed spaces with cold-storage rooms, what is one of the protective measures required by CSA B52?

    <p>A suitable alarm system inside the room</p> Signup and view all the answers

    What instruction is stated in CSA B52 regarding the posting of operating directions in the vicinity of refrigerant compressors?

    <p>Complete operating directions and precautions in case of breakdown or leakage</p> Signup and view all the answers

    According to CSA B52, where should all pipe connections be made with relation to the tank in an ammonia system relief valve discharge protective equipment setup?

    <p>Only through the top of the tank</p> Signup and view all the answers

    What does CSA B52 require the owner of a refrigeration system to place near the refrigerant compressors for providing operation and safety instructions?

    <p>A card with emergency response numbers and shutdown instructions</p> Signup and view all the answers

    In enclosed spaces that are maintained by a refrigeration system at health-detrimental temperatures, what provision must be made according to CSA B52?

    <p>Second door or knockout panel inside the space</p> Signup and view all the answers

    What emphasis does CSA B52 place on the details of personal protective equipment for refrigeration system installation and service personnel?

    <p>Details left to each jurisdiction</p> Signup and view all the answers

    What kind of water is required to absorb discharged ammonia in an alternative arrangement for pressure relief valve discharge?

    <p>Distilled water</p> Signup and view all the answers

    In what manner should discharged ammonia enter the tank in an alternative arrangement for pressure relief valve discharge according to CSA B52?

    <p>Into the center of the tank near the bottom</p> Signup and view all the answers

    What is a requirement for emergency discharge systems in refrigeration plants?

    <p>The emergency valve must be in a glass-fronted box outside the building.</p> Signup and view all the answers

    What is the purpose of a diffuser installed at the upper end of the emergency discharge line in a refrigeration plant?

    <p>To disperse the refrigerant above the roof and away from building openings.</p> Signup and view all the answers

    What is the function of the bright red box housing the emergency valve in a refrigerating plant?

    <p>To ensure the valve can only be accessed by authorized personnel.</p> Signup and view all the answers

    When placing the diffuser at the upper end of the emergency discharge line, how far should it be set back from the roof edge and building openings?

    <p>Not less than a radius of 5 m from any windows or openings.</p> Signup and view all the answers

    What is a crucial feature of the emergency discharge line in a refrigerating plant?

    <p>Absence of any other valve between the emergency valve and the vessel.</p> Signup and view all the answers

    Why should the emergency valve in a refrigerating plant be installed on a horizontal pipe outside the building?

    <p>To distance it from unauthorized personnel and prevent tampering.</p> Signup and view all the answers

    What is required to be tested and proved tight after complete installation and before operation in a refrigeration system?

    <p>High or low side of each system</p> Signup and view all the answers

    When may a pressure-limiting device be omitted on a refrigeration system according to regulations?

    <p>For factory-sealed systems with less than 10 kg of Group A1 refrigerant</p> Signup and view all the answers

    What must discharge to the outside of the building in an approved manner as per the regulations?

    <p>Pressure relief devices</p> Signup and view all the answers

    What should the seats and discs of pressure-relief devices be constructed of to resist refrigerant corrosion?

    <p>Stainless steel</p> Signup and view all the answers

    What are installed in such a way that they are readily accessible for inspection and repair?

    <p>Pressure-relief devices</p> Signup and view all the answers

    What should be checked for accuracy prior to testing in a refrigeration system?

    <p>Pressure gauges</p> Signup and view all the answers

    What may be discharged into the low side of a system if not affected by back pressures?

    <p>Pressure-relief valves</p> Signup and view all the answers

    What is the setting of the pressure-limiting device with a pressure-relieving device in the system?

    <p>No more than 90% of the high-side design pressure</p> Signup and view all the answers

    Which part of a refrigeration system is protected by a pressure-relief device?

    <p>High or low side</p> Signup and view all the answers

    Which devices are connected as directly as possible to the pressure vessel for safe operation?

    <p>Fusible plugs</p> Signup and view all the answers

    What must be provided for every 1 kg of ammonia in an ammonia system tank?

    <p>At least 10 litres of fresh water</p> Signup and view all the answers

    What is required in order to prevent ammonia-absorbing water from freezing in an ammonia system tank?

    <p>No chemicals</p> Signup and view all the answers

    Where should all pipe connections be placed in an ammonia system tank?

    <p>Through the top of the tank only</p> Signup and view all the answers

    Which type of valve is required to discharge ammonia into the center of an ammonia system tank near the bottom?

    <p>Discharge valve</p> Signup and view all the answers

    According to CSA B52, what is the requirement regarding employees' personal protective equipment for working on a refrigeration system?

    <p>Personal protective equipment is required and must be supplied by the owner</p> Signup and view all the answers

    What must personnel have when working on a refrigeration system according to CSA B52, Clause 9.1.2?

    <p>Personal protective equipment</p> Signup and view all the answers

    What is required for a cold storage room that is maintained by a refrigeration system at temperatures detrimental to health according to CSA B52?

    <p>A door that can be readily opened from the inside</p> Signup and view all the answers

    Which component should enclosed spaces maintained by refrigeration systems have if an alarm system is used?

    <p>A suitable alarm system</p> Signup and view all the answers

    What should be provided if other personnel are not available at all times to respond to an alarm in a cold-storage room, according to CSA B52?

    <p>A second door or knockout panel that can be readily opened from within</p> Signup and view all the answers

    According to CSA B52, what information must the owner provide near refrigerant compressors?

    <p>Directions for operating the system and emergency contacts</p> Signup and view all the answers

    Study Notes

    Automatic Expansion Valve

    • Main function is to regulate refrigerant flow based on evaporator pressure.
    • The diaphragm is the component that pushes the valve open.
    • When the compressor stops, the automatic expansion valve closes due to loss of evaporator pressure.
    • Increased evaporator pressure pushes against the diaphragm, causing it to move.
    • The spring assists in adjusting the desired evaporator pressure during operation.
    • Increased evaporator pressure causes the valve to open wider to accommodate more refrigerant flow.

    Refrigeration System Components

    • The capillary tube is used for controlling refrigerant flow to the evaporator, providing a constant liquid supply.
    • Efficient condensers, such as shell-and-tube or air-cooled condensers, are commonly used in refrigeration systems.
    • The solenoid coil deactivates when the compressor stops, closing any connected valves.
    • Bellows in pressure-operated throttling valves respond to changing pressure to adjust flow rate.
    • Flow control of cooling water through the condenser prevents overheating and maintains efficiency.

    Thermostatic Expansion Valve

    • When the compressor starts, the valve plunger in the thermostatic expansion valve opens to allow refrigerant in.
    • The heat exchanger primarily removes heat from the refrigerant, facilitating the refrigeration cycle.
    • Regulation of the compressor output achieves refrigeration control by modulating compressor speed or capacity.
    • Bimetallic strips made of Invar and brass or steel are used for direct temperature control.
    • Bending in bimetallic strips occurs due to temperature-induced expansion differences between metals.

    Control Mechanisms

    • Pressure-actuated controls regulate compressor operation based on system pressure.
    • Automatic expansion valves cannot be used with certain control mechanisms that operate on different principles.
    • Refrigerant flow to the evaporator is regulated by controlling the valve position based on pressure changes.
    • The bellows or diaphragm in indirect control systems move in response to temperature changes sensed outside the valve.
    • High-pressure controls in refrigeration systems include a 'lock-out' feature to prevent operation under unsafe conditions.

    Safety Devices

    • Pressure-relief devices are mandated to prevent overpressure situations in refrigeration systems.
    • Pressure-limiting devices must be connected at strategic locations to effectively mitigate pressure risks.
    • A pressure relief valve functions by opening at preset pressures to release excess pressure safely.
    • Systems operating above atmospheric pressure and with large refrigerant quantities require pressure-limiting devices according to CSA B52.

    Oil Pressure Failure Switch

    • The oil pressure failure switch detects low oil pressure and can shut down the compressor to prevent damage.
    • If the oil pressure differential does not meet the cut-in point within a preset time, the system can trigger shut-off.
    • The heater circuit in the oil pressure failure switch prevents condensation and ensures operational readiness.

    Fusible Plug and Relief Devices

    • Fusible plugs melt due to excess heat, allowing refrigerant to escape and preventing explosions.
    • Stop valves are prohibited between pressure relief devices and the parts of the refrigeration system they protect to ensure safety.
    • Accessibility of pressure relief devices allows for easier inspection and maintenance, enhancing system reliability.

    General Notes

    • Careful control of refrigerant flow and pressure in refrigeration systems ensures optimal performance and safety.
    • Understanding the function and interaction of various components, including valves and control systems, is crucial for efficient refrigeration management.
    • Proper implementation of safety features and controls is essential for compliant operation according to regulatory standards like CSA B52.

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    Description

    Learn about the automatic expansion valve in refrigeration systems, and how it functions to maintain a constant pressure within the evaporator. Understand the components and operation of the valve, including the diaphragm, opening spring, and its role in regulating pressure.

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