Commercial Refrigeration Flow Controls ISKPT 123
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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.