Commercial Refrigeration Systems Study Guide: Compressors, Oil Separators, and Safety, Study notes of Engineering

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FRONT RANGE COMMUNITY COLLEGE

CURRICULUM CONTENT GUIDE

FOR

HVA 122

COMMERCIAL REFRIGERATION

VI. COURSE OUTLINE AND EXPECTED OUTCOMES

This course outline is a topical outline which may not represent the exact sequence of course material.

1. 0 Commercial Refrigeration Systems 1.1 The student should: 1.1.1 Identify different types of cases, coolers, and freezers used in commercial systems. 1.1.2 List differences between commercial, residential, and industrial refrigeration. 1.1.3 Discuss the needs for refrigeration to preserve food, provide process cooling in manufacturing, and allow long term storage for research. 1.1.4 Describe special refrigeration systems for snowmaking and the transportation industry. 1.1.5 Explain the importance of temperature and humidity control in food preservation. 1.1.6 List employers in the commercial refrigeration industry. 1.1.7 Develop a list of potential customers for a commercial refrigeration company. 1.1.8 Identify working conditions, wages, benefits, and responsibilities of a commercial refrigeration technician. 1.1.9 Complete a list of desirable characteristics of a commercial refrigeration technician.
2. 0 Commercial Compressors 2.1 The student should: 2.1.1 Classify compressors used in commercial refrigeration by the type of drive used, the designed temperature range and methods of cooling compressors. 2.1. 2 Compare the operation of reciprocating, centrifugal, rotary, screw and scroll compressors. 2.1. 3 Identify types of capacity control used on commercial compressors. 2.1. 4 Distinguish between the different methods of lubricating compressors. 2.1. 5 Identify routine maintenance procedures required on commercial compressors. 2.1. 6 Disassemble, explain, assemble, pressure test, efficiency test, and operate a commercial compressor. 2.1. 7 Demonstrate methods of reclaiming the refrigerant from a commercial unit. 2.1. 8 Select the proper sequence to isolate the refrigerant charge in the system. 2.1. 9 Calculate the capacity of a reciprocating compressor using the RPM and displacement of the cylinders.
3. 0 Condensers 3.1 The student should: 3.1.1 Describe common types of air cooled condensers. 3.1. 2 Perform maintenance procedures on air cooled condensers including cleaning and straightening fins.

3.1.3 List factors which affect the efficiency of air cooled condensers. 3.1.4 Select correct opera ting temperatures and pressures for air cooled condensers. 3.1.5 Describe methods of head pressure control on outdoor air cooled condensers in low ambient conditions. 3.1.6 List installation requirements for air cooled condensers. 3.1.7 Describe common types of water cooled condensers. 3.1.8 List factors which affect the efficiency of water cooled condensers. 3.1.9 Perform maintenance procedures on water cooled condensers. 3.1.10 Determine correct temperatures and pressures for water cooled units 3.1.11 Explain how head pressure is controlled on water cooled units. 3.1.12 Discuss methods of heat reclaim employed on water cooled and air cooled condensers. 3.1.13 Explain maintenance procedures for cooling towers. 4.0 Evaporators 4.1 The student should: 4.1.1 Identify air cooling and submerged evaporators. 4.1.2 Classify air cooling evaporators according to the type of connection used and the method of defrosting required for each type. 4.1.3 List factors that affect heat transfers in an evaporator. 4.1.4 Compare the types of evaporators available to their correct application, by determining the correct temperature difference and relative humidity to be maintained for proper product storage. 4.1.5 Determine the correct evaporator pressure temperature relationships for common refrigerants. 4.1.6 Discuss how the evaporator capacity is calculated. 4.1.7 Perform preventive maintenance on commercial evaporators.

5. 0 Metering Devices 5.1 The student should: 5.1.1 Match terms associated with flow controls to their correct definitions 5.1.2 Explain the functions of common refrigerant flow controls. 5.1.3 Select uses of capillary tube systems in commercial refrigeration systems. 5.1.4 Determine correct applications of automatic expansion valves. 5.1.5 Install and adjust an automatic expansion valve. 5.1.6 Determine selection criteria for thermostat expansion valves. 5.1.7 Disassemble, explain, assemble, install, test, and adjust super heat on a thermostatic expansion valve. 5.1.8 List uses of high and low side floats for refrigerant flow control. 5.1.9 Explain the operation of a thermal-electric expansion valve.
6. 0 Refrigerants 6.1 The student should: 6.1.1 List the characteristics and properties of commonly used refrigerants in commercial refrigeration..

8.1.7 Describe the function of and test procedures for check valves. 8.1.8 Draw a diagram of and list the purpose of a receiver tank. 8.1.9 List installation requirements and functions of vibration eliminators. 8.1.10 Choose characteristics of systems which require crankcase heaters. List the types, functions, and test procedures for crankcase heaters. 8.1.11 List the location and functions of commercial system mufflers.

9. 0 Ice Machines 9.1 The student should: 9.1.1 State reasons for the growing demand for ice by convenience stores, fast food outlets, grocery stores and restaurants. 9.1.2 List reasons that ice machines require more frequent service than other commercial refrigeration units. 9.1.3 Describe the basic ice making cycle for ice cubes and icemakers. 9.1.4 Discuss why the shape and clarity of ice is important to the consumer. 9.1 5 Compare types of evaporators used in icemakers. 9.1.6 Identify methods of initiating and terminating the harvest cycle of ice cubers. 9.1.7 State the functions and troubleshooting techniques for solid state boards used in icemakers. 9.1.8 Calculate the ice production of an ice cuber. 9.1.9 Calculate the ice production of an ice flaker. 9.1.10 Demonstrate ability to install, troubleshoot, and maintain ice flakers and cubers.
10. 0 Commercial Heat Load Calculations and Pipe Sizing 10 .1 The student should: 10.1.1 Select walk-in cooler and freezer construction materials. 10.1.2 Calculate the heat leakage load of a cooler. 10.1.3 Calculate the air change load in a cooler. 10.1.4 Calculate the product load on a cooler. 10.1.5 Calculate the miscellaneous loads associated with coolers and freezers. 10.1.6 Determine the total heat load using the long method. 10.1.7 Determine the total heat load using charts and tables. 10.1.8 Use a computer program to determine heat loads. 10.1.9 Determine the evaporator and condensing unit capacities. 10.1.10 Calculate the refrigerant line sizes needed for the walk-in cooler 10.1.11 Select appropriate evaporators, condensing units, and refrigerant lines from manufacturer s catalogs. 10.1.12 Price the time and materials needed to install the walk-in cooler in the form of a bid. 10.1.13 Draw an installation diagram of the cooler, including all components and refrigerant lines. 10.1.14 Draw a wiring diagram of the cooler, including power source, controls, circuits, and loads.
11. 0 Troubleshooting Commercial Systems 11.1 The student should:

11.1.1 Find and repair problems in reach-in cases, walk-in units, ice makers, ice cubers, and display cases. 11.1.2 Describe preventive and routine maintenance procedures for commonly used commercial systems.

INFORMATION SHEET # OBJECTIVE: Upon completion of this assignment, the student will know the job responsibilities, desirable employee qualities, occupational outlook and occupational hazards of a refrigeration and air-conditioning technician. INTRODUCTION: A refrigeration and air conditioning technician is someone who:

1. Plans layout, installs, and repairs air-conditioning equipment and systems
2. Plans new or modified installations to minimize waste of materials, plans access for future maintenance to prevent unsightly and hazardous wiring and plumbing so as to be consistent with local specifications and electrical codes.
3. Prepares sketches showing location of plumbing and wiring of the systems, and/or follows diagrams or blue prints, insuring that all concealed plumbing or wiring is installed prior to completion of future walls, ceilings, and floors.
4. Measures, cuts, flares, bends, threads, assembles, and installs refrigerant tubing, piping, and electrical conduits using tools such as tubing cutter, hacksaw, pipe cutter, threading machine, threading dies, tubing and conduit benders, brazing torch, and brazing materials, and safety equipment.
5. Pulls wire through conduit.
6. Splices wires by stripping insulation from terminal leads with knife or stripping pliers, twisting or soldering wires together, and by applying tape or wire nuts.
7. Installs controls and distribution components, such as switches, relays, and circuit breaker panels, fastening in place with screws or bolts using hand tools and power tools.
8. Connects power cables from source to central air conditioning and heating systems and to commercial refrigeration and air conditioning systems.
9. Tests continuity of circuits to insure electrical compatibility and safety of components, using testing instruments, such as ohmmeter, battery, and buzzer or test light.
10. Observes operation and functioning of the installed equipment and/or systems to detect hazards and need for adjustments, relocation, and/or replacement.
11. Repairs faulty or malfunctioning equipment or systems. Some refrigeration and air conditioning technicians may find themselves working on large construction sites or in large factories. All refrigeration and air conditioning

technicians must have a fundamental knowledge of electricity and must be able to read blueprints and troubleshoot electrical circuits. There are certain things a potential employer expects from an employee. Some of these things are:

1. Good work attitude.
2. Being punctual.
3. Work well with others.
4. Safety conscious, follows all safety regulations.
5. Take instructions readily.
6. Control temper at all times.
7. Effective communication with customers and other employees.
8. Exhibit pride in the refrigeration and air conditioning profession.
9. Practice conservation of material and man-hours.
10. Must be mobile. The above list does not cover everything nor is it in set order. Different employers look for different things and each has his or her ideas as to what priority the list should be in. However, the list is a good sample to follow and practice while you are enrolled as a student. Along with learning the skill of a refrigeration and air conditioning technician, you should try to improve in the area listed above. Physical strength is essential to becoming a refrigeration and air conditioning technician as all systems are usually bulky and heavy. Manual dexterity, agility, and good health are important. Good color vision is usually necessary because electrical wires are frequently identified by color. Experienced refrigeration and air conditioning technicians can advance to become supervisors, superintendents, or contract estimators. Many technicians start their own business. The occupational outlook for refrigeration and air conditioning technicians is controlled by:
11. Construction of new homes and commercial buildings.
12. Renovation of existing homes and commercial buildings.
13. Increased utilization of refrigeration and air conditioning equipment.

HVA 122.

OCCUPATIONAL INTRODUCTION

J.S. #

1. A refrigeration and air conditioning technician often is required to prepare sketches showing location of plumbing and wiring on a system. True/False
2. A refrigeration and air conditioning technician never works on electrical circuits, that is an electricians job. True/False
3. A refrigeration and air conditioning technician can look forward to advancement and possibly to being an owner or manager of a shop. True/False
4. The knowledge of a refrigeration and air conditioning technician is considerable. He must have an understanding and skill in refrigeration systems and the electrical circuits and controls used with a system. True/False
5. A electrician is always employed to do all of the work installing or troubleshooting a refrigeration system. True/False
6. A plumber is always employee to do all of the piping work that is used with a refrigeration system. True/False
7. Plumbing codes of local or state laws do not have to be adhered to by a refrigeration and air conditioning technician. True/False
8. A refrigeration and air conditioning technician does not have to follow local electrical codes as he/she is not an electrician. True/False
9. Piping used on a refrigeration system must be carefully installed to make the system function properly. The technician must be able to determine that the piping is installed properly. True/False
10. It is very important to install the equipment and piping in a good workmanship fashion to make the installation appear good. True/False

HVA 122.

SAFETY

I.S. # OBJECTIVE: Upon completion of this assignment, the student will: (1) Know general safety practices for shop work, (2) be familiar with fire prevention practices, and (3) have a thorough understanding of electrical safety hazards and prevention measures. INTRODUCTION: Prevention is the best medicine for injury. Respect all voltages, have a knowledge of the principles of electricity, and follow safe work procedures. Don’t take chances. Personal safety rules:

1. When working on or near rotating machinery, secure loose clothing and tie hair (if long).
2. Check all line (power) cords before using and if the insulation is brittle and/or cracked, DO NOT USE, and report it to the instructor.
3. When measuring voltage with a meter and test probe, be careful not to connect yourself to a voltage of any value.
4. Be certain the floor is insulated either by tile, rubber mats, or the wearing of rubber- soled shoes.
5. When measuring voltage expected to be greater than 50 volts, turn off or disconnect line circuits before connecting test equipment. Always treat voltage of 30 volts or over with great respect.
6. It is recommended that only equipment with a polarized (3 prongs) plug be used.
7. Do not defeat the purpose of any safety device such as fuses, circuit breakers, or interlocks. Shorting across these devices could destroy or seriously damage equipment being worked on as well as cause a fire.
8. Do not carry sharp-edged or pointed tools in your pockets.
9. Do not indulge in horseplay or play practical jokes in any work area.
10. Always wear gloves and goggles when required.
11. Do not wear rings or other jewelry when working with mechanical or electrical devices.
12. Exercise good judgment and common sense.

7. Whenever possible, pull on a wrench - don’t push.
8. Be sure hammer heads and screwdriver blades are fastened tightly in their handles.
9. Use safety glasses or goggles when soldering or unsoldering. Power tool safety precautions Power tools usually operate on 120 volts. This voltage can cause serious shock, burns, or under certain conditions, death. Always check the power tool before you use it. Be sure the cord is in good condition and that the plug and switch are not broken.
10. Keep the cord clear of the work.
11. When drilling, use a sharp drill bit, excessive pressure on a dull bit can cause an accident.
12. Securely fasten the work being drilled or worked on. The drill could turn the work which is a common cause of injury.
13. Be sure your hands are dry before using electric power tools. Be sure you are standing on a dry surface.
14. Keep all power tool guards in place. They were installed for you protection.
15. Operate power tools only after you have had instruction in their uses.
16. Be sure to wear safety goggles or glasses when operating power tools. Flying chips have damaged many peoples eyes.
17. Power cords and switches should be checked to be in good condition before being used. Electrical cord safety rules
18. Do not overload a circuit by connecting numerous cords to a single outlet by using a “multiple plug” adapter.
19. Do not pull the cord to disconnect. Pull plug.
20. Do not use electrical cord with frayed or worn insulation or other damage. Replace or repair as necessary.
21. Do not suspend electrical cords over nails or pipes.
22. Never run electrical cords (1) near heating devices, like space heaters or radiators, (2) across walkways, (3) under carpets or rugs, and (4) through door jambs. Safety Color Codes

Federal Law (OSHA) has established specific colors to designate certain cautions and dangers. Study the colors until you are familiar with all of them. OSHA safety color codes: Red Fire protection equipment and apparatus, portable container of flammable liquids and emergency stop buttons and switches. Yellow Caution (marking physical hazards) waste containers for explosive or combustible materials; caution against starting using or moving equipment under repair; and identification of the starting point or power source of machinery. Orange Dangerous parts of machines, Safety starter buttons and the exposed parts (edges) of pulleys, gears rollers, cutting devices, and power jaws. Purple Radiation hazards. Green Safety, location of first aid equipment (other than fire fighting equipment).

Figure 1 on the following page illustrates some of the common fire extinguishers and their uses. NOTE:Carbon tetrachloride and other toxic, vaporizing-liquid fire extinguishers are prohibited by Federal law. (OSHA). Fire extinguishers are normally red. If they are not red, they should have a red background so the can be easily located. If firefighters are called, be ready to direct them to the fire. Also inform them of any special problems or conditions that exist, such as downed electrical wires or leaks in gas lines. A final thought -- Report to your instructor any accumulations of rubbish or unsafe conditions that could be a fire hazard. Lifting Many times a refrigeration technician is called upon to lift objects. The following lifting techniques should be used.

1. Keep back straight.
2. Lift with your legs.
3. Get help for heavy objects. Ladder Usage When a ladder is used on the job, safely precautions such as the following should be practiced: Step Ladders--
4. Never leave tools or equipment on footsteps or top.
5. Never stand on ladder tops.
6. Never use damaged ladders until repaired.
7. Set ladders on firm, level surface. NOTE: Block up legs if necessary to firm up a ladder.
8. Never use aluminum ladders in electrical work.
9. Have attendant if ladder is located in a walkway or roadway. Job Built and Extension Ladders --

1. Secure top of ladder when possible.
2. Make sure ladder is tall enough. NOTE: Top step should be platform height so that the worker can exit through rails rather than around.
3. Use nonskid feet or secure the base. Maintain safe ladder angle. First Aid If you are called upon to render first aid in case of electrical shock, keep a level head and remember the following: (these procedures apply to 120-240 volt locations)
4. Locate live wire and safely disconnect it if possible. ( CAUTION : Do not take hold of the person or uninsulated wire with your bare hand.)
5. Decide whether it would be easier to move the person, throw the main breaker or move the conductor. ( CAUTION : If the conductor is to be moved use dry limb or some other nonconductive equipment. If a person’s body is to be moved use several thicknesses of paper or cloth as an insulator.)
6. With paper or cloth in hand, quickly pull victim free of the conductor. (NOTE: These decisions must be made quickly. After five minutes the chances of saving an individual decrease greatly.)
7. Examine the victim immediately after the victim is no longer connected to the electrical circuit.
8. If the victim is breathing normally and the heart beat is regular, she/he will probably recover without further trouble. The victim should have a check-up by a doctor afterwards.
9. If the victim has stopped breathing, start artificial resuscitation immediately. The mouth-to-mouth technique should be used.
10. If someone is around, have them call a doctor. Do not leave the victim. Administer mouth-to-mouth while waiting for someone to pass by. Continue the mouth-to-mouth until the doctor arrives.