4BE3 U6 C5 Obj 3 EMH
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Questions and Answers

EASY Why is propylene glycol used instead of ethylene glycol in certain situations?

  • Because it is less toxic (correct)
  • Because it is more viscous
  • Because it has a longer life span
  • Because it is cheaper

    • What is the primary reason for not mixing ethylene glycol and propylene glycol?

  • They can cause inhibitors to precipitate (correct)
  • They have different pH levels
  • They have different specific heats
  • They have different viscosities

    • What is the purpose of adding corrosion inhibitors to glycol heat transfer fluids?

  • To react with oxygen to form organic acids
  • To decrease the viscosity of the glycol
  • To prevent corrosion caused by the reaction of glycol with oxygen (correct)
  • To increase the pH of the system

    • Why is automotive glycol not recommended for industrial closed loop systems?

    <p>Because it has a shorter life span</p> Signup and view all the answers

    What is the typical pH range of a glycol system with adequate inhibitor?

    <p>Between 9 and 9.5</p> Signup and view all the answers

    What happens to the pH of a glycol system if the inhibitor is consumed?

    <p>It decreases to below 8</p> Signup and view all the answers

    Which glycol requires the most pumping power?

    <p>Propylene glycol</p> Signup and view all the answers

    Which glycol has the lowest specific heat?

    <p>Propylene glycol</p> Signup and view all the answers

    What is the advantage of using propylene glycol over ethylene glycol?

    <p>It is less toxic</p> Signup and view all the answers

    What is the minimum glycol concentration recommended to avoid biological fouling?

    <p>20%</p> Signup and view all the answers

    What is the advantage of using glycol systems in remote sites?

    <p>They require less monitoring</p> Signup and view all the answers

    What happens to the heat transfer capacity of a system when converted from water to glycol?

    <p>It decreases by 50%</p> Signup and view all the answers

    Why should automatic municipal water make-up not be used in glycol systems?

    <p>It dilutes the mixture and reduces its freeze point</p> Signup and view all the answers

    What type of water should be mixed with glycol according to glycol manufacturers?

    <p>Demineralized, distilled, or deionized water</p> Signup and view all the answers

    What is the maximum level of chlorides permitted in dilution water for glycol systems?

    <p>25 ppm</p> Signup and view all the answers

    Why should glycol not be used directly in a boiler or heater system?

    <p>It breaks down when exposed to high heat transfer surface temperatures</p> Signup and view all the answers

    MEDIUM What is the primary reason for the higher cost of glycol systems compared to water systems?

    <p>Higher cost of glycol compared to water</p> Signup and view all the answers

    What is the minimum recommended glycol concentration to prevent biological fouling?

    <p>20%</p> Signup and view all the answers

    Why are glycol systems a better option for remote sites?

    <p>They require less monitoring</p> Signup and view all the answers

    What is the purpose of using a special tank and pump system for make-up in glycol systems?

    <p>To prevent dilution of the glycol mixture</p> Signup and view all the answers

    What is the maximum level of sulfates permitted in dilution water for glycol systems?

    <p>25 ppm</p> Signup and view all the answers

    Why is a heat exchanger necessary between the boiler and the closed loop system?

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

    What is the effect of using automatic municipal water make-up in glycol systems?

    <p>It dilutes the glycol mixture and reduces its freeze point</p> Signup and view all the answers

    What is the recommended range of glycol concentrations for temperatures between −15 to −20°C?

    <p>30-35%</p> Signup and view all the answers

    What is the chemical formula of ethylene glycol?

    <p>(CH2OH)2</p> Signup and view all the answers

    Why do glycol heat transfer fluids require corrosion inhibitors?

    <p>To prevent the formation of organic acids that increase corrosion</p> Signup and view all the answers

    What happens when ethylene glycol and propylene glycol are mixed together?

    <p>Inhibitors precipitate and the mixture gels</p> Signup and view all the answers

    What is the primary difference between propylene glycol and ethylene glycol in terms of freeze protection?

    <p>Propylene glycol requires a higher concentration to provide the same freeze protection</p> Signup and view all the answers

    Why is it important to monitor the pH of a glycol system?

    <p>To determine if the inhibitor is being consumed</p> Signup and view all the answers

    What is a common problem that can occur in glycol systems if the pH drops below 7?

    <p>The system requires a full internal cleaning and replacement of the glycol solution</p> Signup and view all the answers

    What is the main reason why propylene glycol is more viscous than ethylene glycol?

    <p>It has a different chemical structure</p> Signup and view all the answers

    What is a common service offered by glycol suppliers to help maintain the effectiveness of their products?

    <p>Free inhibitor analysis</p> Signup and view all the answers

    HARD What is the primary reason why glycol systems require corrosion inhibitors?

    <p>To prevent corrosion from oxygen</p> Signup and view all the answers

    What is the effect of mixing ethylene glycol and propylene glycol together?

    <p>Inhibitors precipitate out and the mixture gels</p> Signup and view all the answers

    Why is it important to monitor the pH of a glycol system?

    <p>To check if the inhibitor is being consumed</p> Signup and view all the answers

    What happens to the pH of a glycol system if the inhibitor is consumed?

    <p>The pH decreases</p> Signup and view all the answers

    Why is propylene glycol more viscous than ethylene glycol?

    <p>Because of its chemical structure</p> Signup and view all the answers

    What is a common problem that can occur in glycol systems if the pH drops below 7?

    <p>The system likely requires a full internal cleaning and replacement of the glycol solution</p> Signup and view all the answers

    What is a service offered by some glycol suppliers?

    <p>Inhibitor analysis</p> Signup and view all the answers

    What is the primary reason why glycol systems require less monitoring compared to water systems?

    <p>Because glycol systems are less prone to biological fouling</p> Signup and view all the answers

    What happens to the heat transfer capacity of a system when converted from water to glycol?

    <p>It decreases by over 50%</p> Signup and view all the answers

    Why is corrosion a concern in glycol systems?

    <p>Because glycol reacts with oxygen to form organic acids</p> Signup and view all the answers

    What is the purpose of using a special tank and pump system for make-up in glycol systems?

    <p>To prevent dilution of the glycol mixture</p> Signup and view all the answers

    What is the recommended minimum glycol concentration to prevent biological fouling?

    <p>20%</p> Signup and view all the answers

    What is the maximum level of total hardness permitted in dilution water for glycol systems?

    <p>100 ppm</p> Signup and view all the answers

    Why should glycol not be used directly in a boiler or heater system?

    <p>Because it breaks down when exposed to high heat transfer surface temperatures</p> Signup and view all the answers

    What is the primary reason why propylene glycol is more expensive than ethylene glycol?

    <p>Because it is less toxic than ethylene glycol</p> Signup and view all the answers

    What is the recommended concentration range of ethylene glycol for temperatures between −35 to −40°C?

    <p>45 – 55%</p> Signup and view all the answers

    Study Notes

    Glycol in Closed Systems

    • Glycol is added to prevent freezing damage in closed system heating or cooling water.
    • There are two main types of glycol: ethylene glycol [(CH2OH)2] and propylene glycol [C3H8O2].
    • Ethylene glycol is toxic, while propylene glycol is not, making it suitable for use where food products are involved.

    Characteristics of Glycols

    • Glycols are more viscous than water, requiring more pumping power.
    • Propylene glycol is the most viscous and requires a higher concentration to provide the same freeze protection as ethylene glycol.
    • Both glycols have lower specific heats than water, with propylene having the lowest.
    • Propylene glycol is more expensive than ethylene glycol.
    • Table 3 shows the recommended glycol concentrations to achieve desired freeze protection:
      • Temperature range −35 to −40 °C: 45-55% ethylene glycol, 50-54% propylene glycol
      • Temperature range −15 to −20 °C: 30-35% ethylene glycol, 35-40% propylene glycol
    • Glycol concentrations should never be less than 20% to prevent biological fouling.

    Converting to Glycol Systems

    • Glycol systems require less monitoring and are suitable for remote sites.
    • Glycol solutions transfer less than half the heat of water, reducing heat transfer capacity by over 50%.
    • Converting a water system to a glycol system increases costs and requires greater pumping power.

    Maintenance and Inhibitors

    • Glycol reacts with oxygen to form organic acids, increasing corrosion.
    • Corrosion inhibitors are added to glycol heat transfer fluids.
    • pH levels indicate the presence of adequate inhibitor, with a pH range of 9-9.5 being optimal.
    • Test kits are available to check inhibitor levels.

    Important Considerations

    • Automotive glycol should not be used in industrial closed-loop systems.
    • Ethylene glycol and propylene glycol should not be used together.
    • Glycol should not be used directly in boiler or heater systems.
    • A heat exchanger should be used between the boiler and the closed-loop system.

    Glycol in Closed Systems

    • Glycol is added to prevent freezing damage in closed system heating or cooling water.
    • There are two main types of glycol: ethylene glycol [(CH2OH)2] and propylene glycol [C3H8O2].
    • Ethylene glycol is toxic, while propylene glycol is not, making it suitable for use where food products are involved.

    Characteristics of Glycols

    • Glycols are more viscous than water, requiring more pumping power.
    • Propylene glycol is the most viscous and requires a higher concentration to provide the same freeze protection as ethylene glycol.
    • Both glycols have lower specific heats than water, with propylene having the lowest.
    • Propylene glycol is more expensive than ethylene glycol.
    • Table 3 shows the recommended glycol concentrations to achieve desired freeze protection:
      • Temperature range −35 to −40 °C: 45-55% ethylene glycol, 50-54% propylene glycol
      • Temperature range −15 to −20 °C: 30-35% ethylene glycol, 35-40% propylene glycol
    • Glycol concentrations should never be less than 20% to prevent biological fouling.

    Converting to Glycol Systems

    • Glycol systems require less monitoring and are suitable for remote sites.
    • Glycol solutions transfer less than half the heat of water, reducing heat transfer capacity by over 50%.
    • Converting a water system to a glycol system increases costs and requires greater pumping power.

    Maintenance and Inhibitors

    • Glycol reacts with oxygen to form organic acids, increasing corrosion.
    • Corrosion inhibitors are added to glycol heat transfer fluids.
    • pH levels indicate the presence of adequate inhibitor, with a pH range of 9-9.5 being optimal.
    • Test kits are available to check inhibitor levels.

    Important Considerations

    • Automotive glycol should not be used in industrial closed-loop systems.
    • Ethylene glycol and propylene glycol should not be used together.
    • Glycol should not be used directly in boiler or heater systems.
    • A heat exchanger should be used between the boiler and the closed-loop system.

    Glycol in Closed Systems

    • Glycol is added to prevent freezing damage in closed system heating or cooling water.
    • There are two main types of glycol: ethylene glycol [(CH2OH)2] and propylene glycol [C3H8O2].
    • Ethylene glycol is toxic, while propylene glycol is not, making it suitable for use where food products are involved.

    Characteristics of Glycols

    • Glycols are more viscous than water, requiring more pumping power.
    • Propylene glycol is the most viscous and requires a higher concentration to provide the same freeze protection as ethylene glycol.
    • Both glycols have lower specific heats than water, with propylene having the lowest.
    • Propylene glycol is more expensive than ethylene glycol.
    • Table 3 shows the recommended glycol concentrations to achieve desired freeze protection:
      • Temperature range −35 to −40 °C: 45-55% ethylene glycol, 50-54% propylene glycol
      • Temperature range −15 to −20 °C: 30-35% ethylene glycol, 35-40% propylene glycol
    • Glycol concentrations should never be less than 20% to prevent biological fouling.

    Converting to Glycol Systems

    • Glycol systems require less monitoring and are suitable for remote sites.
    • Glycol solutions transfer less than half the heat of water, reducing heat transfer capacity by over 50%.
    • Converting a water system to a glycol system increases costs and requires greater pumping power.

    Maintenance and Inhibitors

    • Glycol reacts with oxygen to form organic acids, increasing corrosion.
    • Corrosion inhibitors are added to glycol heat transfer fluids.
    • pH levels indicate the presence of adequate inhibitor, with a pH range of 9-9.5 being optimal.
    • Test kits are available to check inhibitor levels.

    Important Considerations

    • Automotive glycol should not be used in industrial closed-loop systems.
    • Ethylene glycol and propylene glycol should not be used together.
    • Glycol should not be used directly in boiler or heater systems.
    • A heat exchanger should be used between the boiler and the closed-loop system.

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    Description

    This quiz covers the use of glycol in industrial cooling systems, including the differences between ethylene glycol and propylene glycol, and the importance of using the non-toxic type in food-related applications. Learn about the properties and safety considerations of these substances.

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