Oct 04, 2022  

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HVAC 123 - Commercial Refrigeration Flow Controls I

Credits: 3
Develops an understanding of basic skills necessary for servicing of commercial units such as walk-in coolers, reach-ins, display cases, and commercial icemakers. Analyzes refrigeration flow-control components, system components, and piping practices. Credit may be earned in one of the following: HVAC 123 or SKPT 123 .

Prerequisite(s): HVAC 121   
Corequisite(s): HVAC 122   is recommended
Lecture Hours: 35 Lab Hours: 10
Meets MTA Requirement: None
Pass/NoCredit: Yes

Outcomes and Objectives
  1. Demonstrate knowledge of refrigerants and EPA standards.

    A. Study the characteristics of refrigerants.
    B. Identify refrigerant classifications, properties, and types.
    C. Identify refrigerant oils and their properties.
    D. Identify proper refrigerant recovery methods.
    E. Identify proper evacuation methods.
    F. Demonstrate how a refrigerant safety matrix works.
    G. Identify which refrigerants are used for low temperature, and which for medium temperature.
    H. Explain temperature glide and fractionation.
  2.  Demonstrate knowledge of evaporator characteristics.

    A. Explain how an evaporator operates.
    B. Identify design temperatures used in evaporators.
    C. Identify refrigeration circuit design and fin designs used for evaporators.
    D. Identify characteristics of distributor design used on multiple circuit evaporators.
    E. Explain the states of the refrigerants and pressures in the evaporator.
    F. Explain superheat, saturation point, and their relationship to the evaporator.
  3. Demonstrate knowledge of condenser characteristics.
    1. Explain how a condenser operates.
    2. Identify design temperatures used for air-cooled condensers.
    3. Identify design temperatures for water-cooled condensers
    4. Explain condenser sub cooling.
    5. Calculate the condenser sub cooling on a refrigeration unit with an air-cooled condenser.
    6. Explain the relationship to the condenser of the discharge line and the refrigerant receiver.
    7. Identify the proper charging capacity of a refrigerant receiver at 120 degrees Fahrenheit.
    8. Explain how a water-cooled condenser operates.
    9. Demonstrate methods of adjusting a water-cooled condenser for proper capacity.
    10. Measure sub cooling from heat exchange devices or sub coolers.
    11. Find the total system sub cooling.
  4. Demonstrate knowledge of basic commercial refrigeration components.
    1. Identify these components
      1. Compressor
      2. Discharge line
      3. Condenser
      4. Receiver
      5. Liquid line
      6. Liquid line drier and site glass
      7. Expansion device (expansion valve)
      8. Evaporator
      9. Accumulator
      10. Suction line
      11. Refrigeration service valves
    2. Identify the refrigerant pressures in these refrigeration components.
    3. Identify the states of the refrigerants in these refrigeration components.
    4. Apply gauges to the system and measure system pressures.
  5. Demonstrate knowledge of expansion valve operation and performance.
    1. Explain how an expansion valve operates.
    2. Identify the components of an expansion valve.
    3. Identify expansion valve types.
    4. Explain how to use the number system on an expansion valve to identify its capacity and correct application.
    5. Identify and measure superheat
    6. Explain the need to use an external equalized valve.
    7. Demonstrate correct superheat measurement.
    8. Demonstrate correct expansion valve adjustment.
    9. Identify correct piping methods for single evaporators and expansion valves.
    10. Identify correct piping methods for multiple evaporators and expansion valves.
  6. Demonstrate knowledge of refrigeration piping methods.
    1. Explain refrigeration piping rules for vertical suction lines.
    2. Explain refrigeration piping rules for horizontal suction lines.
    3. Explain how refrigeration line sizing effects system pressure drop and system oil return.
    4. Identify the equivalent feet of pressure drop for refrigeration fittings.
    5. Explain how to use refrigeration pressure drop and velocity line size charts.
    6. Identify special piping procedures to assist proper velocity and pressure drop.
    7. Identify correct pressure drops for suction lines, discharge lines, and liquid lines.
    8. Identify correct pressure drops for suction line driers, liquid line driers, and evaporators.
    9. Identify correct refrigerant velocities for suction lines, discharge lines, and liquid lines.
  7. Demonstrate knowledge of the mechanical characteristics of refrigerant compressors.
    1. Identify mechanical components and operation of refrigerant compressors.
      1. Piston

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