311 Questions
What are the three main types of compressor regulation systems mentioned in the text?
Start-and-Stop, Variable Speed, Constant Speed
When does the compressor start in a start-and-stop control system?
At minimum receiver pressure
Which type of compression system is typically used for utility air systems with generally steady load demand?
Start-and-Stop Control system
What are two conditions that can make start-and-stop control uneconomical?
Almost continuous demand for air and large air receiver
What is the starting torque like in a sliding vane compressor compared to full load torque?
Less than full load torque
Which type of compressor is most suitable for a start-and-stop control system according to the text?
Small reciprocating compressor
What happens when the receiver reaches the set pressure in the compressor system?
A small piston opens a port for air passage
What is an advantage of the suction-unloading valve described in the text?
Quick change of compressor suction valves
What can result from the compressor and suction piping operating under a vacuum?
Increased gasket leaks
How is control achieved for a sliding vane compressor using start-stop control?
Low pressure in the receiver
What is an advantage of load-unload control for a rotary compressor?
Reduced energy consumption
In the described load-unload control for a rotary compressor, what happens when the delivery pressure exceeds the required setting?
Air is admitted to the top of the operating piston
What is the danger associated with the method of controlling the compressor by closing the suction valves?
Compressor cylinder overheating
What happens when the suction-unloading valve is closed according to the text?
The compressor operates at full power
What is the operation of the valve based on in load-unload control for a rotary compressor?
High-pressure air controlled by a pilot valve
What is the method used to control the load for rotary compressors as discussed in the text?
Modulating inlet valve
Which control method is used to maintain a constant system pressure by varying the compressor speed?
Variable Speed Control
Which constant speed control method holds the inlet valve in the open position to prevent air from being trapped inside the cylinder?
Inlet air unloader
What type of control is used automatically unload the compressor during motor start-up?
Inlet air unloader
What happens when the air receiver pressure rises to the preset cutout pressure in a pilot valve?
The piston is forced downwards
What is the disadvantage of using an inlet air unloader?
It results in extra repair costs and longer downtime
What happens when the demand for air decreases in a variable speed control system?
The receiver pressure increases
Which control method is used on a compressor that runs at constant speed?
Constant speed control
What type of compressor is most likely to go into a surge condition when the speed is reduced too much?
Dynamic compressors
What happens when the manual unload handle on the side of the pilot valve is used for start-up of the compressor?
The compressor starts in the unloaded position
What is the advantage of using a suction line unloading valve?
It can be used where the compressor load changes frequently
What is the purpose of the handle labeled 'handle in start position' in the pilot valve diagram?
To start the compressor in an unloaded position
What is the function of the pressure transmitter in a modulating system?
To send a signal to the regulating valve controller
What is the advantage of a modulating inlet valve control system?
It is more energy efficient as power consumption is directly linked to load demand
What is the disadvantage of inlet vane control for dynamic compressors?
The compressor can go into a surge condition if the load demand is reduced significantly
What is the role of microprocessors in rotary air compressors?
To replace the analog controller
What is the function of electrical transducers and sensors in microprocessor-based control systems?
To sense variables such as air pressure and flow
What is the advantage of microprocessor-based control systems over pneumatic control systems?
They are faster and more accurate
What is the function of mechanical trip switches in electro-pneumatic control systems?
To discontinue compressor operation when pressures or temperatures reach critical levels
What type of control system is preferred for processes with complicated and varying demand cycles?
Microprocessor-based control
What is the function of a suction line unloading valve?
Prevents gasket leaks in the compressor and piping
In which scenario is there slight compression in each end of the compressor cylinder but no air is delivered?
When the suction line unloading valve is closed
What happens when the pilot-operated inlet valve in a rotary compressor opens?
Air is admitted to the top of the piston and the suction is shut off
What is the primary disadvantage of closing suction valves in a compressor?
Poses a danger of over heating the compressor cylinder
What is the main advantage of load-unload control for a rotary compressor?
Reduces power absorbed by the compressor to about 20% of full load
Why is the control strategy associated with closing suction valves considered complex?
Poses challenges in managing air compression in the cylinder
What is the role of the adjusting nut in the suction-unloading valve?
Adjusts the operating range of the unloader
What happens when the suction-unloading valve is closed in terms of compressor operation?
The compressor and piping operate under vacuum
Why can start-and-stop control for a sliding vane compressor be considered energy efficient?
The driver is started at a low pressure and stopped at high pressure
What makes load-unload control for rotary compressors suitable for steady load demands?
The piston moves downwards to shut off suction
Which type of compressor control system is most suitable for a small reciprocating or sliding vane compressor according to the text?
Start-and-stop control
What proportion of full-load speed must a sliding vane compressor achieve before the sliding vanes begin to function?
40%
Which two conditions can make start-and-stop control uneconomical for a compressor?
An almost continuous demand for air and an air receiver that is too small
Which type of compressor is most likely to go into a surge condition when the speed is reduced too much?
An axial flow compressor
What is the main purpose of the control systems for a compressor?
To regulate the output of the compressor in accordance with the volume of air required
Which type of control system is used on a compressor that runs at constant speed?
Start-and-stop control
What is one of the disadvantages of using an inlet air unloader in a reciprocating compressor control system?
The unloader must be removed before the valve can be repaired, resulting in extra repair costs and longer downtime.
What is the function of a spring-loaded piston in the pilot valve used for an inlet air unloader?
To hold the piston in the closed position.
What is the purpose of the manual unload handle on the side of the pilot valve in an inlet air unloader?
To force the piston down and allow the receiver pressure to hold the inlet valves open during compressor start-up.
What problem can arise when the compressor and suction piping operate under a vacuum?
The compressor can go into a surge condition.
Which constant speed control method for reciprocating compressors uses a suction unloading valve?
Suction line unloading valve.
What does the adjusting nut in a suction unloading valve control?
The amount of unloading required by the compressor.
What is the primary purpose of control systems for a compressor?
To maintain a constant system pressure by varying the compressor speed.
Which control method is used to automatically unload the compressor during motor start-up?
Inlet air unloader.
What happens when the pilot-operated inlet valve in a rotary compressor opens?
The compressor speed is increased or reduced according to system pressure.
What is the main advantage of using microprocessor-based control systems over pneumatic control systems?
They offer more precision and flexibility.
What is the primary purpose of the modulating inlet valve control system?
To adjust the compressor capacity to match the load demand
Which type of compressor control system is preferred for processes with complicated and varying demand cycles?
Microprocessor-based control
What is the function of electrical transducers and sensors in microprocessor-based control systems?
To monitor air pressure and flow
What is the disadvantage of inlet vane control for dynamic compressors?
It can cause the compressor to go into a surge condition
What is the purpose of the handle labeled 'handle in start position' in the pilot valve diagram?
To start the compressor in an unloaded position
What is the advantage of microprocessor-based control systems over pneumatic control systems?
They are faster and more accurate
What is the function of mechanical trip switches in electro-pneumatic control systems?
To discontinue compressor operation when pressures or temperatures reach critical levels
What is the primary advantage of modulating inlet valve control?
It provides a steady system pressure
What is the role of microprocessors in rotary air compressors?
To replace the analog controller
What causes surging in a compressor?
When the flow through the compressor drops to a point where the pressure being generated is not sufficient to maintain flow out of the compressor
What happens when the pressure in the discharge line drops below the surge point?
The air will again flow through the compressor
What is one of the methods used to prevent surging in a compressor?
Closing the discharge line blow-off valve to atmosphere
What causes the shock wave in a compressor during surging?
The reversal of flow caused by the insufficient pressure being generated
What type of compressors are subject to surging?
Centrifugal and axial compressors
What happens to the direction of flow when surging occurs in a compressor?
The direction of flow reverses
What is the primary function of the anti-surge valve in a compressor control system?
To recirculate air from the discharge to the suction
What input signals does the surge controller receive?
Inlet air flow, suction pressure, and discharge pressure
What happens when the discharge pressure falls below a certain value for a corresponding flow rate in an anti-surge control system?
The anti-surge valve opens to recirculate air
What is the purpose of the two pressure inputs to the surge controller?
To ensure a certain pressure differential across the compressor
What happens to the anti-surge valve when the compressor shuts down or is shut down for any reason?
It opens to recirculate air
What is the purpose of the air cooler in a discharge recirculation valve (anti-surge valve) system?
To prevent the compressor from overheating
Why does surging occur in a compressor?
The flow through the compressor is insufficient to maintain pressure.
How may surging impact the impeller or piping in a compressor?
It may create a shock wave that can damage components.
What is the purpose of a discharge line blow-off valve in preventing surging?
To allow air to escape to atmosphere when flow decreases.
What characteristic of the pressure-volume curve indicates the surge point for a centrifugal compressor?
The curve's highest point.
What condition is necessary for a blow-off valve to open in a compressor system?
Flow from the compressor drops to a certain level.
How does surging affect the flow direction within a compressor?
It causes the flow to reverse direction.
What happens when the surge controller receives input indicating that the pressure differential across the compressor is too high?
The compressor will shut down due to a suspected problem with the compressor.
What occurs when the anti-surge controller begins to close the anti-surge valve after the compressor is up to speed on start-up?
The compressor will start to overheat.
If the surge controller senses low discharge pressure at a certain flow rate, what action will be triggered in response?
The surge controller starts to open the recycle flow valve.
What is the purpose of modern surge control technology that involves microprocessor controllers?
To stabilize the compressor for particular flow rates.
What function does the anti-surge valve serve when the compressor is shut down for any reason?
It will recirculate air back to the suction of the compressor.
What is the role of the discharge recirculation valve in preventing a surge condition in the compressor?
It sends flow back to the suction of the compressor to increase mass flow.
What is the primary reason for removing water vapour from compressed air?
To prevent water hammer or damage from freezing
What effect does oil vapour have on air-operated instruments?
It has a detrimental effect
What is the purpose of an intercooler in an air compressor system?
To reduce air temperature and condense moisture
What is the main purpose of intercoolers in compressors?
To reduce the power required to compress air
Why is it important for intercoolers to have drains?
To remove condensed water and oil
What is the role of an aftercooler in an air compressor system?
To cool the compressed air before delivery
What is one of the additional purposes for cooling air in a compressor?
To reduce the possibility of an explosion of any air/oil vapour mixture
What is the primary function of a discharge line blow-off valve in preventing surging?
To decrease the discharge pressure
Why should aftercoolers have water separators installed?
To collect the moisture condensed out of the air stream
What is the role of the discharge recirculation valve in preventing a surge condition in the compressor?
To increase the recirculation of discharge air
What distinguishes the aftercooler in Figure 12 from the pipeline aftercooler?
Cooling mechanism
Why are finned tubing used in air compressors?
To increase the heat transfer area
What should be maintained slightly above the pressure dewpoint in a properly designed intercooler?
Outlet temperature
In water-cooled intercoolers, what mechanism is employed to direct the air flow around the tubes?
Baffle plates
Why does moisture condense out of the air stream in the intercooler?
As a result of decreased temperature
What is the primary purpose of an intercooler in an air compressor system regarding the entrained moisture?
To condense a large portion of the entrained moisture
What is the primary purpose of intercoolers and aftercoolers in a multistage compressor system?
To remove water vapour and oil vapour from the air
What happens to water vapour and oil vapour when the air is cooled in an intercooler or aftercooler?
They condense and can be drained
Why is it important to remove water vapour from the air in a compressor system?
To prevent water hammer and damage from freezing
What is an additional benefit of cooling the air during compression?
It increases the efficiency of operation
What is a consequence of not removing oil vapour from the air?
It can have a detrimental effect on air-operated instruments
What is the purpose of water jacketing compressors, in addition to using intercoolers?
To aid in removing the heat of compression
What is the primary function of the intercooler in an air compressor system?
To reduce the air temperature between compression stages
Which component in the intercooler system is responsible for removing condensed water and oil?
The automatic condensate drain
What type of cooling method is typically used in pipeline aftercoolers?
Water cooling
What is the primary purpose of an aftercooler in an air compressor system?
To cool the compressed air prior to delivery to the point of use
Which component is responsible for changing the direction of the air stream in order to remove moisture and other particles in the aftercooler?
The water separator
Which type of compressor control system is most suitable for a small reciprocating or sliding vane compressor, according to the text?
Load-unload control
Which component in the intercooler system is responsible for preventing surging in the compressor?
The safety valve
What type of compressor is most likely to go into a surge condition when the speed is reduced too much?
Dynamic compressors
Which type of compressor control system is typically used for utility air systems with generally steady load demand?
Load-unload control
What is the primary advantage of using microprocessor-based control systems over pneumatic control systems in air compressors?
Faster response times
What is the main purpose of the prefilters in an instrument air system?
To remove moisture and oil vapors from the air stream
What is the function of the coalescing filters in an instrument air system?
To gather together tiny moisture droplets from the air stream
What is the purpose of the afterfilter in an instrument air system?
To remove particulates from the air stream
What is the main purpose of using refrigerated dryers in an instrument air system?
To lower the dew point of the air
What is the difference between heated and heatless desiccant dryers in an instrument air system?
Heated desiccant dryers use a heater to regenerate the moisture-laden bed
What is the main purpose of using desiccant dryers in an instrument air system?
To lower the dew point of the air
What mechanism is employed in a finned tube air-cooled aftercooler to direct the air flow around the tubes?
Vanes
What effect does the compressor intake air temperature have on the air dryer dew point?
The dew point increases with increasing intake air temperature
What is the purpose of ensuring the aftercooler discharge temperature does not get too high in an instrument air system?
To avoid overloading the air dryers with moisture
What is the purpose of using coalescing filters in an instrument air system?
To gather together tiny moisture droplets from the air stream
What is the primary purpose of the instrument air system?
To provide dry air for all instrumentation
What is the function of the inlet filter in the air system?
To prevent dust and particles from entering the compressor
What is the difference between the air in the wet receiver and the dry receiver?
The air in the dry receiver is dryer than the air in the wet receiver
Why should the inlet air be supplied from an atmosphere away from engine or process exhaust outlets?
To prevent contaminants from entering the compressor
What is the purpose of the aftercooler in the air system?
To cool down the air stream and remove moisture
Why is it important to have the inlet piping at least as large as the compressor intake connection?
To prevent inlet flow restriction
What is the primary function of the wet air receiver in an instrument air system?
To stabilize the flow through the air dryers on system load changes
What type of air compressor is shown in Figure 14?
Rotary Screw oil-free air compressor
What is the purpose of the prefilter and afterfilter in the air dryer package?
To ensure clean air to the instruments
Why is an elaborate filtering system required if the air compressor is to be oil-lubricated?
To ensure oil-free air
What is the function of the moisture separator in an instrument air system?
To remove moisture condensed in the aftercooler
What is the primary function of the dry air receiver in an instrument air system?
To serve as a demand reservoir for the instrument air system
What is the purpose of the control system in the packaged air compressor?
To vary the compressor load by means of a modulating inlet valve
Why are coalescing filters used in an instrument air system?
To remove oil from the air
What is the benefit of using a microprocessor-based control system?
It provides more precise control and monitoring capabilities
What is the main function of the wet air receiver in the instrument air system?
To act as an additional moisture separator to reduce the amount of moisture going to the air dryers
Which component in a packaged air compressor serves the function of remove condensed water from the compressed air?
Moisture Separator
What is the primary function of a dry air receiver in an instrument air system?
To stabilize the system pressure as a demand reservoir
In a compressor system, what is the purpose of using coalescing filters?
To remove oil from the air to ensure oil-free compressed air
What effect does a dry air receiver have on the air purification system during surges in air demand?
Help avoid overloading the air purification system
What is the function of the moisture separator in an air compressor system?
To remove condensed water from the air stream
Which function does the wet air receiver in an instrument air system serve in preventing compressor cycling on sudden load changes?
Provide storage capacity
What is the role of coalescing filters in an oil-lubricated air compressor?
Remove oil from the compressed air
Why does the wet air receiver help in stabilizing the flow through the air dryers in an instrument air system?
To reduce moisture going to the air dryers
What would happen if an elaborate filtering system is not used in an oil-lubricated air compressor to ensure oil-free air?
The air would not be suitable for instrument use
Which type of dryer does not use heat to regenerate the moisture-laden bed?
Heatless type
Which type of filter is not used in an instrument air system?
Microfilter
What happens if the aftercooler discharge temperature gets too high?
The air dryers become overloaded with moisture.
What material is used in a heated desiccant dryer for the adsorption process?
Alumina
Which pressure does not fluctuate in the instrument air system?
Air supply system pressure
What happens if the compressor and suction piping operate under a vacuum?
Air can be trapped inside the cylinder causing a surge condition.
What happens when the air in the compressor intake is very dry?
The dew point decreases.
What is the primary purpose of the modulating inlet valve control system in compressors?
To maintain a constant discharge line pressure.
Which of the following is not a type of compressor regulation system?
Hybrid compressor control system
Which of the following does not affect the operating parameters of an instrument air system?
Compressor intake air volume.
What is the primary purpose of the air system in a plant?
To provide dry air for instrumentation
What happens to the air in the wet receiver?
It is drier than atmospheric air, but not as dry as instrument air
Why is it important to install an air filter in the inlet line of the compressor?
To prevent dust and other particles from being carried into the compressor
What is the purpose of the aftercooler in the air system?
To cool the compressed air
What is the difference between instrument air and utility air?
Instrument air is drier than utility air
Where should the inlet air be supplied from?
From a location away from engine or process exhaust outlets
What could happen if the pressure dewpoint of the air begins to rise from -60°C to -40°C?
Moisture may accumulate in the instrument air lines
Where is the moisture-sensing probe typically placed in relation to air dryers with an afterfilter?
Downstream of the afterfilter
What happens to the desiccant in the glass bulb of an air dryer if the outlet air from the dryer is wet?
It changes color
How does the dewpoint analyzer measure the pressure dewpoint of the compressed air?
By converting moisture content to a numeric value
In what way does the moisture content in the air affect the moisture-sensing probe's resistance?
It creates a higher electrical resistance
What is one of the main functions of the portable dew point monitor attached downstream of the air dryers?
To prevent moisture accumulation in the air lines
What is the primary purpose of a desiccant in a desiccant dryer system?
Perform the drying function by adsorbing water vapor
In a regenerative air dryer system, what is the purpose of using heated air for regeneration?
To carry away the condensed water from the desiccant
What is the role of a restriction orifice in a regenerative air dryer system?
To create a pressure drop allowing flow through the regenerating dryer
How are the desiccant beds in a desiccant dryer system regenerated in a heatless dryer?
By depressurizing the bed to atmospheric pressure
What is the purpose of a pressure dewpoint in air compressor systems?
To indicate the temperature at which moisture will condense at system pressure conditions
How does a timer system or PLC control the cycling of the two towers in a desiccant dryer system?
By controlling the regeneration valves and timing sequence
What happens to the water vapor in the desiccant bed during the regeneration process?
It evaporates into the low vapor pressure purge air
Why is it necessary to remove a desiccant bed before it becomes saturated in a desiccant dryer system?
To prevent moisture carryover
What does a dewpoint temperature indicate in compressed air applications?
The temperature at which liquid water forms from moisture in the air
Which component is responsible for carrying away the condensed water from the desiccant in a regenerative air dryer system?
Purge air
What is the primary purpose of air dryers in an instrument air system?
To reduce the dew point of the air
What is the function of the heater in an air dryer system?
To heat the air during regeneration
What happens when Dryer 'A' is in adsorption mode?
The wet air flows up through the bed and the dry air leaves through the top valve
What is the purpose of the afterfilters in an air dryer system?
To ensure no desiccant particles enter the air system
What is the function of the switching valves in an air dryer system?
To direct flow for the appropriate cycle, adsorption or regeneration
What happens to Dryer 'B' during regeneration?
A small air blower draws in atmospheric air and blows it through a heater, down through the bed, then out to atmosphere
What is the primary function of the cartridge-type after filters in an adsorbent air dryer package?
To ensure no desiccant particles enter the air system
What distinguishes a heated regeneration type air dryer from a heatless regenerating type?
The use of a heater to blow hot air through the bed
What is the purpose of the three-way switching valves attached to each dryer in an adsorbent air dryer package?
To direct the flow of air for the appropriate cycle, either adsorption or regeneration
What is the consequence of not adequately reducing the dew point of the air in a refrigerant type air dryer?
There will be water contamination of the air operated instruments and freezing problems with the air system in cold weather
How does the regeneration cycle in a refrigerant type air dryer work?
By blowing hot air through the desiccant bed
What is the main difference between the prefilters and afterfilters in an air dryer system?
The prefilters are used to remove solid particles and afterfilters are used to remove moisture
What is the primary function of the restriction orifice in the air supply line of a regenerative air dryer system?
To create a pressure drop that allows flow through the regenerating dryer
How does the system ensure that the desiccant bed is not completely saturated with water vapour?
By continuously monitoring the moisture levels using sensors
What is the purpose of reducing the pressure to atmospheric pressure during regeneration in a heatless dryer?
To reduce the dewpoint and vapour pressure
What component in the intercooler system is responsible for preventing surging in the compressor?
There is no such component mentioned in the text
What happens when the system pressure is 690 kPa gauge, and the dewpoint of the air is minus 40°C at 0 kPa gauge?
The dewpoint of the air decreases
What type of dryer uses a blower and internal electric heaters to heat the purge air?
Regenerative air dryer system
What is the difference between Atmospheric Dewpoint and Pressure Dewpoint?
Atmospheric Dewpoint is the temperature at which moisture will condense at ambient air conditions, while Pressure Dewpoint is the air temperature which moisture will condense at system pressure conditions
What is the main purpose of using a molecular sieve desiccant?
To achieve lower dewpoints
What is the purpose of a dryer package in Figure 18 using a blower and internal electric heaters to heat the purge air?
To reduce the dewpoint of the air
What is the primary difference between Atmospheric Dewpoint and Pressure Dewpoint?
The pressure conditions at which moisture will condense
What happens to the electrical current flowing between the two electrodes in the moisture-sensing element when the air from the dryer flows through it?
It is resisted by the moisture content in the air
Where is the moisture-sensing probe typically placed in an instrument air system with an afterfilter?
Downstream of the afterfilter
What is the purpose of the glass bulb with desiccant in some air dryer systems?
To indicate the moisture content of the air
What is the function of the analyzer in a dewpoint analyzer system?
To convert the electrical signal to a numeric value
Why is it important to check the dewpoint of the compressed air regularly?
To prevent moisture from accumulating in the instrument air lines
What is the component that converts the electrical signal to a numeric value in the dewpoint analyzer system?
Dewpoint analyzer
What is the purpose of the air blower in the regeneration cycle of an air dryer?
To draw in atmospheric air and blow it through a heater, down through the bed, then out to atmosphere
What is the function of the three-way switching valves in an air dryer package?
To direct the flow of air for the appropriate cycle, adsorption or regeneration
What is the role of the after filters in an air dryer system?
To ensure that no desiccant particles enter the air system
What is the primary purpose of prefilters in an instrument air system?
To filter out solid particles from the compressed air
What happens when the delivery pressure exceeds the required setting in a load-unload control for a rotary compressor?
The suction valve opens to unload the compressor
How does the compressor intake air temperature affect the air dryer dew point?
The dew point increases as the intake air temperature increases
What is the primary purpose of an intercooler in an air compressor system?
To lower the temperature of the compressed air
What is the purpose of monitoring the pressure dewpoint of the compressed air?
To prevent moisture accumulation in the instrument air lines
Which material is typically used for the desiccant in a desiccant dryer system?
Silica gel or activated alumina
Where is the moisture-sensing probe typically placed in relation to air dryers with an afterfilter?
Downstream of the air dryer and afterfilter
What is the primary function of the moisture sensor in a desiccant dryer system?
To monitor the moisture content in the air
How does the moisture-sensing element in the probe respond to changes in air moisture content?
By creating a resistance to the electrical current
What is the primary purpose of a coalescing filter in an instrument air system?
To remove oil vapour
What control system is often used for cycling between the drying and regeneration cycles in a desiccant dryer system?
PLC-based control
What is the purpose of the small glass bulb filled with desiccant in some air dryer systems?
To indicate air moisture content
What is the primary purpose of the modulating inlet valve control system in an air compressor system?
To regulate output air pressure
What is the function of the analyzer in the dewpoint analyzer system?
To convert the electrical signal to a numeric value
What is the advantage of using a portable analyzer to measure pressure dewpoint?
It can be used at multiple sampling points
What is the function of the moisture separator in an air compressor system?
To remove moisture
What happens to the electrical current flowing between the two electrodes in the moisture-sensing element when the air from the dryer flows through it?
Decreases
What is the primary purpose of the control system in a packaged air compressor?
To regulate output air pressure
What is the effect of the air intake temperature on the air dryer dew point in a compressor system?
Inversely proportional
What happens to the desiccant bed in a heatless dryer before it enters the regeneration cycle?
Becomes completely saturated
What is the purpose of using the term 'purge air' in the context of regenerating a desiccant bed?
Removing water vapor from the desiccant bed
Why is the pressure in the chamber reduced to atmospheric pressure before the purge airflow is started in the regeneration cycle?
To reduce its dewpoint and vapor pressure
How does the desorbed condensate travel in the desiccant dryer system during the regeneration cycle?
Vents to atmosphere
In the context of the desiccant dryer system, what is the purpose of the timer system or PLC?
Controlling the regeneration cycle
Why is it crucial to monitor the dewpoint in a desiccant dryer system?
To prevent water vapor condensation
What triggers the regeneration valves to cycle between the drying and regeneration cycles in a desiccant dryer system?
Timer system or PLC
How does a desiccant bed become 'saturated' in the context of a desiccant dryer system?
By adsorbing moisture to capacity
What is the role of the molecular sieve desiccant in a desiccant dryer system?
Achieving lower dewpoints
Why is the cycling of the two towers between the drying and regeneration cycles an essential aspect of a desiccant dryer system?
To maintain the dryness of the air
What is the primary purpose of the pair of three-way switching valves attached to each dryer in an adsorbent air dryer package?
To direct flow for both adsorption and regeneration cycles
What happens to the dry air in Dryer 'A' after it leaves the top valve?
It passes through a set of cartridge-type after filters
What is the role of the heater in the regeneration cycle of Dryer 'B'?
To heat the atmospheric air that blows through the bed
What is the purpose of the cartridge-type after filters in an adsorbent air dryer package?
To ensure no desiccant particles enter the air system
What is the state of Dryer 'B' when atmospheric air is blown through a heater, down through the bed, then out to atmosphere?
Regeneration
Why are there two towers in an adsorbent air dryer package?
So that one is adsorbing while the other is either regenerating or on standby
What is the purpose of the stainless steel housing with several holes in the moisture-sensing probe?
To allow the flow of air through the housing
What happens to the electrical current flowing between the two electrodes in the moisture-sensing element when the air from the dryer flows through?
It creates a resistance
What is the purpose of the afterfilter in relation to the moisture-sensing probe?
To protect the probe from desiccant dust
What happens to the desiccant in the glass bulb of an air dryer system when the air is dry?
It turns blue
What is the function of the analyzer in a dewpoint analyzer system?
To measure the dew point of the compressed air
What is the purpose of checking the pressure dewpoint of the air on a regular basis?
To prevent moisture accumulation in the instrument air lines
What step must be taken to ensure the compressor cylinders are protected from damage due to overheating?
Turn on the cooling water for the compressor cylinders.
What is the purpose of ensuring all required safety guards are put back in place before starting the compressor?
To prevent personal injury.
Why should all leaks on flanges be tightened up before starting the compressor?
To ensure efficient compressor operation.
What is the purpose of turning on the cooling water for the compressor cylinders?
To protect the cylinders from overheating.
Why should the compressor be in the unloaded position before starting it?
To avoid overloading the motor.
What should be done if leaks are found on the cooling water system?
Repair them before starting the compressor.
Why is it important to check the crankcase/gearbox oil level?
To ensure the compressor has adequate lubrication
What should you do if the suction and discharge pressures are abnormally low or high?
Shut down the compressor and have the problem rectified
Why is it necessary to check around the compressor for leaks?
To prevent damage to the compressor and surrounding equipment
What can happen if the cylinder lubricator is not working?
The compressor will experience excessive wear of the cylinder walls and pistons
Why is it necessary to ensure the crankcase/gearbox oil levels are at the required levels?
To ensure the compressor has adequate lubrication
What should you do if you notice unusual noises around the compressor?
Find the cause of the noise and have it corrected
What is the consequence of starting the motor when the breaker is being closed?
Triggering excessive wear of the cylinder walls and pistons
What should be done if the cylinder lubricator is not working?
Add additional lube oil
Why is it important to check the cylinder lubricator before starting the compressor?
To mitigate excessive wear on the compressor cylinders
What could happen if the compressor is loaded too quickly?
Lack of lubrication for the compressor cylinders
Why is it necessary to check for leaks around the compressor?
To tighten them up
What is the primary reason for slowly loading the compressor?
To prevent damage to the compressor cylinders
Which action is crucial to prevent overheating damage to the compressor cylinders before starting the unit?
Turn on the cooling water for the compressor cylinders
What is the purpose of ensuring the compressor is in the unloaded position before starting?
To avoid overloading the motor and potentially damaging it
What safety measure should be taken to prevent personal injury when starting the compressor?
Ensure that no one is working on the compressor
Why should leaks on flanges be listened for after opening the suction and discharge valves?
To ensure that all leaks are tightened up before starting the compressor
What is the primary function of the cooling water system in the compressor?
To protect the compressor cylinders from damage due to overheating
What step should be taken to ensure the compressor motor is not overloaded when starting?
Ensure that the compressor is in the unloaded position
What is the first step when starting up the lube oil system?
Listen for any unusual noises in the system
What is the immediate course of action if leaks are observed in the lube oil system during start-up?
Shut down the system and have the leak repaired
What is the next step after confirming no leaks and observing proper lube oil pressure in the system?
Load the compressor slowly or ensure the microprocessor brings the compressor on line properly
What action must be taken if unusual noises are observed in the system?
Immediately shut down the compressor
When should you load the compressor after beginning the start-up procedure?
After confirming no leaks and proper lube oil pressure
Before starting a dynamic compressor/blower, what must be ensured?
That all maintenance personnel have completed their work on the unit
Why is it important to ensure that all manual block valves in the suction or discharge lines are open?
To ensure the system will not shut down due to low suction pressure or high discharge pressure
What should be done to the surge valves before starting the compressor?
They should be wide open
What is the purpose of doing an inspection to ensure all flanges are tight?
To prevent damage to the system or compressor
Why is it important to ensure the lube oil reservoir has an adequate level?
To ensure the compressor lube oil system is ready for service
What should be closed before starting the compressor?
The motor breaker
What must be ensured before starting a dynamic compressor or blower, according to the text?
Surge valves are closed and suction flow control valve is open.
Why is it critical to ensure the surge valves are open and the suction flow control valve is closed before starting the compressor?
To prevent damage to the system due to high suction pressure.
What should be the status of the motor breaker before attempting to start the compressor?
Open and not closed by an electrician.
Why is it necessary to ensure that manual block valves in the suction or discharge lines are open?
To avoid system shutdown due to low suction pressure or high discharge pressure.
Why is it crucial to inspect that all flanges are tight and tools have been removed from the compressor unit before starting?
To prevent personal injury.
What step ensures that the compressor lube oil system is ready for service, according to the text?
Verify that the lube oil reservoir has an adequate level of oil.
What should be checked and corrected, if found, before loading the compressor during its start-up procedure?
Insufficient flow of lube oil to all the bearings
During start-up, what immediate action should be taken if leaks are observed in the lube oil system?
Shut down the system and repair the leak
Which component in the intercooler system is responsible for preventing surging in the compressor?
The anti-surge valve
How does a desiccant bed become 'saturated' in the context of a desiccant dryer system?
When the desiccant material adsorbs water vapour from the air stream
What should be done if the cylinder lubricator is not working during the start-up procedure?
Shut down the compressor and repair the lubricator
Learn about the different types of control systems used in air compressors to regulate their output and maintain the receiver pressure within operating limits. Explore Start-and-Stop Control, Variable Speed Control, and Constant Speed Control methods.
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