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Commercial Refrigeration Flow Controls I

SKPT 123

Commercial Refrigeration Flow Controls I

SKPT 123

Course Description

Prerequisite: SKPT 122. 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, RHA 123, or SKPT 123. (35-10)

Outcomes and Objectives

Demonstrate knowledge of refrigerants and EPA standards.

Objectives:

  • Study the characteristics of refrigerants.
  • Identify refrigerant classifications, properties, and types.
  • Identify refrigerant oils and their properties.
  • Identify proper refrigerant recovery methods.
  • Identify proper evacuation methods.
  • Demonstrate how a refrigerant safety matrix works.
  • Identify which refrigerants are used for low temperature, and which for medium temperature.
  • Explain temperature glide and fractionation.

Demonstrate knowledge of evaporator characteristics.

Objectives:

  • Explain how an evaporator operates.
  • Identify design temperatures used in evaporators.
  • Identify refrigeration circuit design and fin designs used for evaporators.
  • Identify characteristics of distributor design used on multiple circuit evaporators.
  • Explain the states of the refrigerants and pressures in the evaporator.
  • Explain superheat, saturation point, and their relationship to the evaporator.

Demonstrate knowledge of condenser characteristics.

Objectives:

  • Explain how a condenser operates.
  • Identify design temperatures used for air-cooled condensers.
  • Identify design temperatures for water-cooled condensers
  • Explain condenser sub cooling.
  • Calculate the condenser sub cooling on a refrigeration unit with an air-cooled condenser.
  • Explain the relationship to the condenser of the discharge line and the refrigerant receiver.
  • Identify the proper charging capacity of a refrigerant receiver at 120 degrees Fahrenheit.
  • Explain how a water-cooled condenser operates.
  • Demonstrate methods of adjusting a water-cooled condenser for proper capacity.
  • Measure sub cooling from heat exchange devices or sub coolers.
  • Find the total system sub cooling.

Demonstrate knowledge of basic commercial refrigeration components.

Objectives:

  • Identify these components
  • Identify the refrigerant pressures in these refrigeration components.
  • Identify the states of the refrigerants in these refrigeration components.
  • Apply gauges to the system and measure system pressures.

Demonstrate knowledge of expansion valve operation and performance.

Objectives:

  • Explain how an expansion valve operates.
  • Identify the components of an expansion valve.
  • Identify expansion valve types.
  • Explain how to use the number system on an expansion valve to identify its capacity and correct application.
  • Identify and measure superheat
  • Explain the need to use an external equalized valve.
  • Demonstrate correct superheat measurement.
  • Demonstrate correct expansion valve adjustment.
  • Identify correct piping methods for single evaporators and expansion valves.
  • Identify correct piping methods for multiple evaporators and expansion valves.

Demonstrate knowledge of refrigeration piping methods.

Objectives:

  • Explain refrigeration piping rules for vertical suction lines.
  • Explain refrigeration piping rules for horizontal suction lines.
  • Explain how refrigeration line sizing effects system pressure drop and system oil return.
  • Identify the equivalent feet of pressure drop for refrigeration fittings.
  • Explain how to use refrigeration pressure drop and velocity line size charts.
  • Identify special piping procedures to assist proper velocity and pressure drop.
  • Identify correct pressure drops for suction lines, discharge lines, and liquid lines.
  • Identify correct pressure drops for suction line driers, liquid line driers, and evaporators.
  • Identify correct refrigerant velocities for suction lines, discharge lines, and liquid lines.

Demonstrate knowledge of the mechanical characteristics of refrigerant compressors.

Objectives:

  • Identify mechanical components and operation of refrigerant compressors.
  • Identify how to find pulley speeds for open-type compressors.
  • Calculate compression ratio of a system and compressor.
  • Explain compressor efficiency.
  • Disassemble a reciprocating compressor and identify its components.

Demonstrate knowledge of refrigeration regulating and flow control components.

Objectives:

  • Identify the operation of these flow control valves.
  • Diagram the proper installation of these valves and flow controls.
  • Identify methods of testing these controls
  • Identify methods of adjustment for these valves.