MCCCD Program Description

Refrigerants, Refrigerant Flow Control and Defrost Methods

Course: HVA270

First Term: 1996 Spring

Lecture 3 Credit(s) 3 Period(s) 3 Load
Subject Type: Occupational
Load Formula: S

Description: Refrigerant characteristics, classifications and groups, emerging refrigerants, refrigerant flow controls and methods of defrosting evaporator

MCCCD Official Course Competencies
1. Explain the classification and toxicity ratings of refrigerants. (I) 2. Interpret the thermodynamic tables associated with refrigerants. (II) 3. Describe the effects of moisture on refrigerants and the oil- refrigerant relationship. (III) 4. Explain the types, purpose and applications for specific refrigerant drying agents. (IV) 5. Describe the operation and applications of specific refrigerant metering devices. (V) 6. Explain the operation and applications of refrigerant distributors. (VI) 7. Analyze metering device performance due to thermo-bulb and external equalizer location. (VII) 8. Compare and contrast the operation of thermostatic expansion valves to capillary tube and automatic expansion valves. (VIII) 9. Explain the operation liquid level refrigerant controls and pilot control devices. (IX) 10. Compare and contrast specific methods of defrost. (X) 11. Describe the specific methods of multistage compression systems and desuperheat the discharge gas between stages. (XI) 12. Evaluate oil return systems employed in multistage and multi- compressor systems. (XII) 13. Explain the operation of multiple temperature evaporator systems. (XIII)
MCCCD Official Course Competencies must be coordinated with the content outline so that each major point in the outline serves one or more competencies. MCCCD faculty retains authority in determining the pedagogical approach, methodology, content sequencing, and assessment metrics for student work. Please see individual course syllabi for additional information, including specific course requirements.

MCCCD Official Course Outline
I. Refrigerant, classification, and toxicity ratings A. Definitions B. Refrigerant ratings C. Classification D. Toxicity II. Refrigerant thermodynamic tables A. Pressure B. Enthalpy C. Refrigerant states 1. Saturated liquid 2. Sub-cooled liquid 3. Saturated vapor 4. Superheated vapor D. Other III. Refrigerant, moisture, oil relationship A. Refrigerant and moisture relationship B. Refrigerant and oil relationship IV. Refrigerant drying agents A. Drying agents 1. Types 2. Purpose B. Applications V. Refrigerant metering devices A. Operation of specific valves B. Specific applications C. Selection VI. Refrigerant distributors A. Operation B. Selection C. Applications VII. Metering device performance A. Thermo-bulb location B. External equalizer location C. Trap location in respect to thermo-bulb location VIII. Metering devices A. Thermostatic to capillary tube B. Thermostatic to automatic C. Automatic to capillary tube IX. Liquid level refrigerant control and pilot control devices A. Liquid level control B. Pilot control devices X. Defrost methods A. Time and temperature (off cycle) B. Electric C. Hot gas (reverse cycle) D. Cool gas E. Brine F. Heat bank G. Re-evaporator coils H. Multiple evaporators XI. Multistage compression and de-superheating A. Multistage compression methods B. Intermediate stage de-superheating methods XII. Oil return systems A. Multistage systems B. Multi-compressor systems XIII. Multiple temperature evaporator systems A. Operation B. Evaporator pressure regulators C. Solenoid controlled D. Single compressor E. Multi-compressor

MCCCD Governing Board Approval Date: 10/24/1995

All information published is subject to change without notice. Every effort has been made to ensure the accuracy of information presented, but based on the dynamic nature of the curricular process, course and program information is subject to change in order to reflect the most current information available.