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EPA Study guide sec. 608
study guide cards for epa cert. test. sec. 608
296
Mechanical Engineering
01/31/2011

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Term
What are the typical uses of the center port of gauge set?
Definition
Used during evacuation, charging and recovery procedures.
Term
What color are the gauges on a manifold gauge set?
Definition
Low pressure is blue, High pressure is red.
Term
What are the typical ranges of pressure measurements used on the gauges of a manifold gauge set?
Definition
High side is 0 to 500 PSIG; Low side is 0 to 350 PSIG and 0 to 30 in. Hg below atmospheric pressure.
Term
Is the refrigerant leaving a condenser at a high or low pressure? Is it a liquid or a gas?
Definition
High pressure, liquid.
Term
Is the refrigerant entering the expansion valve (variable metering device) a liquid or gas?
Definition
Liquid, high pressure.
Term
Is the pressure of the refrigerant entering the compressor high or low?
Definition
Low pressure vapor.
Term
Where in a refrigerant circuit does a liquid boil to absorb heat?
Definition
In the evaporator.
Term
The refrigerant in the suction line is a gas that has been heated above its saturation. What is this condition called?
Definition
Superheated vapor.
Term
What can cause liquid refrigerant to migrate to a compressor crankcase?
Definition
If the compressor is located in the coldest location in the circuit.
Term
List two conditions that can quickly damage a compressor that is starting to run?
Definition
Operating while in a deep vacuum or when the service valves are closed.
Term
What system failures require taking an oil sample?
Definition
A compressor burnout or if the unit has had a leak.
Term
Is flushing with refrigerant an acceptable tube cleaning method?
Definition
No.
Term
In addition to preventing and repairing leaks, what else should a technician do to conserve refrigerant?
Definition
Recover and recycle used refrigerants.
Term
What factors affect the speed of an evacuation?
Definition
Pump size, hose length, hose diameter, size of system to be evacuated, ambient temperature, suction line size, and the amount of moisture in the system.
Term
How should gauge set hoses be sized for use in evacuating a system?
Definition
Use the shortest length and the largest diameter possible for the quickest evacuation. At least as large as the vacuum pump inlet.
Term
When evacuating, what is the benefit of using short hoses with large diameters?
Definition
Reduces emissions, pressure drop and evacuation time.
Term
which connection determines the preferred size of hoses used with a vacuum pump?
Definition
The vacuum pump inlet.
Term
As the capacity and suction hose size increase, what happens to the time needed for an evacuation?
Definition
Time is reduced.
Term
What purpose is served by heating a system during dehydration?
Definition
To speed up moisture removal.
Term
Does a thorough evacuation remove moisture from a system?
Definition
Yes.
Term
What can happen to oil in the compressor if the moisture is left in an operating system?
Definition
The oil will form hydrofluoric and hydrochloric acids which will corrode the internal parts of the system.
Term
What is the result of over-evacuating a system?
Definition
No damage will be done.
Term
How can a system be leak checked using a low pressure gauge?
Definition
Vacuum reading will rise when vacuum pump is turned off.
Term
How close should the vacuum gauge be connected to the vacuum pump during evacuation?
Definition
As far away as possible.
Term
When measuring the vacuum of a system being evacuated, the system must be isolated. What must be done to the vacuum pump?
Definition
Turn it off and valve it off.
Term
What is ozone?
Definition
3 atoms of oxygen. It blocks much of the harmful ultraviolet radiation (uv-b) emitted from the sun and it keeps our earth's temperature stable.
Term
How much ozone can a chlorine atom destroy in the stratosphere?
Definition
One atom can destroy 100,000 ozone molecules.
Term
What is Ozone Depletion Potential (ODP)?
Definition
The ability of any chemical to deplete the ozone layer.
Term
What is CFC?
Definition
Chlorofluorocarbon.
Term
Which refrigerants are CFC's?
Definition
R-11,12,113,114.
Term
Which chemical in the CFC refrigerants does the most damage to the ozone layer?
Definition
Chlorine.
Term
What is an HCFC?
Definition
Hydrochlorofluorocarbons.
Term
Which refrigerants are HCFC's?
Definition
R-22,123.
Term
Which is more harmful to the ozone layer, a CFC or an HCFC?
Definition
CFC's.
Term
What is it about CFC's that make them more harmful to the stratosphere?
Definition
Chemical strength, they will not breakdown in the lower atmosphere.
Term
What is an HFC?
Definition
A fluorocarbon that contains no chlorine.
Term
Which refrigerants are HFC's?
Definition
R-134a,404a,407c,410a.
Term
What is the ODP of the HFC refrigerant?
Definition
Zero.
Term
Which refrigerants contain chlorine?
Definition
CFC's and HCFC's.
Term
Which refrigerants have high ODP?
Definition
CFC's.
Term
Which refrigerants have low ODP?
Definition
HCFC's, HFC's are zero.
Term
What is an azeotrope refrigerant?
Definition
A mixture of two or more compounds where the mixture behaves like a single chemical.
Term
Is one of the components of R-500 a CFC?
Definition
Yes
Term
Does stratospheric ozone help or hurt the work of the earth's protective shield?
Definition
It helps.
Term
What chemical in the stratosphere tells us ozone depletion is occurring?
Definition
Chlorine-monoxide.
Term
How do we know the chlorine in the stratosphere is coming from CFC's?
Definition
The increase in chlorine and fluorine present in the stratosphere, matches the increase in emissions of CFC's.
Term
How do we know CFC's get to the stratosphere?
Definition
From high altitude air sampling measurements.
Term
What role does the ozone layer play in protecting the earth?
Definition
It blocks much of the harmful ultraviolet radiation (uv-b).
Term
What are the effects on health from increased ultraviolet radiation?
Definition
Skin cancer, cataracts, human immunity is reduced.
Term
What are the effects on the environment?
Definition
Timber growth is reduced, crop yields lowered, marine life and the food chain are impaired.
Term
Is ozone depletion a problem for the United States only or a global problem?
Definition
A global problem.
Term
What is the Montreal Protocol?
Definition
A treaty that called for the reduction of production of CFC's.
Term
The Montreal Protocol calls for the regulation of what chemicals?
Definition
Ozone depleting compounds, CFC's, HCFC's, and Halons.
Term
On what date was the production and importation of all CFC's phased out?
Definition
In the U.S., after December 31, 1995.
Term
Where will we get replacements?
Definition
Through recovery of existing refrigerants.
Term
What steps are called for by the Clean Air Act?
Definition
Taxes on production and use, standards set for the recovery of refrigerants.
Term
What is prohibited by the Clean Air Act?
Definition
Venting.
Term
Do state and local laws have priority over federal law? Can they be less strict?
Definition
No. Cities or states can create their own laws but they must be at least as strict as federal laws.
Term
To prevent damage to the ozone layer, the U.S. is making laws to capture the CFC's now in use. What else does the new law do to restrict the release of CFC's?
Definition
Allows states and municipalities to create their own laws to prevent and monitor the release of CFC and HCFC materials into the atmosphere.
Term
By recovering refrigerants, we ensure adequate supplies and prevent venting. What else does the recovery of refrigerants accomplish?
Definition
Prevents stratospheric ozone depletion.
Term
The Clean Air Act phases out CFC/HCFC production and prohibits venting. What else does it require?
Definition
Standards to be set for recovery of all refrigerants prior to appliance service and disposal.
Term
Falsifying or failing to keep required records, failing to reach required evacuation levels and knowingly releasing CFC or HCFC refrigerants, are a violations of the Clean Air Act. What activity with a substitute refrigerant is also a violation?
Definition
Knowingly venting CFC's, HCFC's and their substitutes.
Term
Which refrigerants must be recovered prior to opening a system?
Definition
All refrigerants as of 11-15-1995.
Term
What releases of a CFC and HCFC are violations of the Clean Air Act?
Definition
Any knowingly vented refrigerants.
Term
On what date did it become illegal to vent CFC and HCFC refrigerants?
Definition
July 1, 1992.
Term
Which appliances are covered by Section 608?
Definition
Any device which contains and uses a class 1 or class 2 substance as a refrigerant and is used for household or commercial purposes.
Term
What is the primary reason the EPA requires a service aperture or process stub on all appliances?
Definition
For adding or removing refrigerant from the appliance.
Term
Who sets the regulations for recovery machines?
Definition
EPA.
Term
What is a "self-contained" recovery machines?
Definition
A recovery machine that has its own compressor to pump refrigerant out of the system.
Term
Is HCFC-123 a "low or "high" pressure refrigerant?
Definition
Low pressure.
Term
Is CFC-12 a "low" or "high" pressure refrigerant?
Definition
High pressure.
Term
What is the smallest container in which refrigerants may be sold to a Section 608 certified technicians.
Definition
20 pounds.
Term
What must you do to the refrigerant in an appliance before disposing of the appliance?
Definition
Recover refrigerant or verify that the refrigerant was previously recovered.
Term
Who is responsible for removing the refrigerant from household refrigerators prior to disposal?
Definition
The final person in the disposal chain. (Scrap metal recyclers, landfill owner, etc)
Term
What is the penalty for violation of the Clean Air Act?
Definition
Fines up to $27,500 per violation per day and possible loss of technician certification.
Term
How much is the bounty for information leading to a conviction?
Definition
Up to $10,000.
Term
What ca happen if a technician cannot demonstrate an ability to use recovery or recycling equipment?
Definition
May result in revocation of the technician's certification.
Term
What is the name of the process that removes refrigerant from a system and stores it without testing or processing?
Definition
Recovery.
Term
What is the name for the process that removes moisture and acids from refrigerant but does not test the refrigerant?
Definition
Recycling.
Term
What is the name for the process that removes moisture and acids from refrigerant and also chemically tests the refrigerant?
Definition
Reclaim.
Term
What must be done with reclaimed refrigerant before it can be legally resold?
Definition
Chemically tested to ARI Standard 700, the purity level of factory new refrigerant.
Term
What is the preferred instrument for detecting small leaks?
Definition
Electronic leak detector and Ultrasonic detector.
Term
What is an inert gas typically used in leak detection?
Definition
Dry nitrogen.
Term
What is typically indicated by a dehydrated system failing to hold a vacuum?
Definition
Leaks.
Term
What should be done when recovering the refrigerant form a system where the refrigerant has been improperly mixed?
Definition
Recover into a separate container?
Term
Can mixed refrigerants be reclaimed?
Definition
No.
Term
What precautions should be taken when recovering refrigerant from systems with multiple service valves?
Definition
Insure that liquid is not trapped between service valves.
Term
What is the effect of low ambient temperature on the time required to complete a recovery of refrigerant?
Definition
Increases recovery time.
Term
Technicians must explain to customers that recovery is necessary and it is required by law. What else should the technician tell the customer?
Definition
That all service personnel are duty bound to follow the law and protect the environment.
Term
What is different about any leaks in systems charged with a blended refrigerant?
Definition
Because they are blended, the ingredients will leak at different rates.
Term
What is "temperature glide"?
Definition
A family of lines depicting pressure versus temperature curve.
Term
What is ternary blend?
Definition
A blend of three different refrigerants.
Term
How should systems using blended refrigerants be charged?
Definition
In liquid form into the high side of the system.
Term
Is there a "drop-in" refrigerant for CFC-12?
Definition
No.
Term
How do you leak check an HFC-134a system with a partial charge (no HFC-134a detector available)?
Definition
Recover the remaining 134a and then pressurize the system with nitrogen and a trace charge of R-22 so you can use an HCFC electronic leak detector.
Term
What is the preferred oil to be used with HFC-134a?
Definition
Ployolester.
Term
Can ester based oils be mixed with other oils?
Definition
No.
Term
What does "hygroscopic" mean?
Definition
Oil that absorbs moisture easily.
Term
What lubricant is recommended for use with a ternary blend?
Definition
Depends on the blend: For HCFC's-Alkylbenze, For HFC's-Ployolester.
Term
Safety glasses and butyl-lined gloves should be worn for what procedures?
Definition
When operating recovery or recycling devices and when handling and refilling refrigerant cylinders.
Term
What safety component must be used whenever dry nitrogen is used to pressurize a system?
Definition
Pressure regulator.
Term
Safety rules for technicians such as: no open flame or hot steam near a refrigerant, never cutting or brazing a charged refrigerant line, and never using oxygen to purge or pressurize lines, are all important. Which one should a technician follow?
Definition
All of them.
Term
What is a Material Safety Data Sheet?
Definition
A sheet the states the safety ratings and precautions to be taken for use and handling of chemicals.
Term
What safety classification within the ASHRAE standard is the most safe?
Definition
A1.
Term
What is caused by tie inhaling of refrigerant vapors?
Definition
Heart irregularities or Asphyxia.
Term
What is the major causes of death involving refrigerants?
Definition
Oxygen deprivation.
Term
What breathing problem can be caused by CFC-12?
Definition
Asphyxia.
Term
How can ice be removed from a sight glass?
Definition
With alcohol spray.
Term
What must be done with a badly corroded relief valve?
Definition
It must be replaced.
Term
Where can you find the allowable test pressure on a system?
Definition
Unit data plate.
Term
Can oxygen be used to check for leaks? If not, why not?
Definition
No. Oxygen in the presence of oil under high pressure can be explosive.
Term
What is the likely result of heating a recovery cylinder with an open flame?
Definition
Refrigerant will decompose into a toxic material, venting of refrigerant int the atmosphere or the tank may explode.
Term
What is the primary purpose of a disposable cylinder?
Definition
For virgin refrigerant from the manufacturer.
Term
To what internal pressure should a disposable cylinder be reduced to for disposal?
Definition
Reduced to at least 0 PSIG.
Term
Should you ever use a disposable cylinder for refrigerant recovery?
Definition
No.
Term
To dispose of a cylinder you should be sure all refrigerant is recovered and the cylinder is no longer usable. What else should you do?
Definition
Puncture the container before disposal.
Term
For safety, refrigerant chlinders should not be rusted or damaged and always properly color coded. What additional step should also be taken with these cylinders?
Definition
Properly secured at all times.
Term
What is the proper color code for recovery cylinders?
Definition
Gray with a yellow top.
Term
What is the maximum percent by weight that a cylinder may be filled?
Definition
80%.
Term
What can happen if a cylinder is overfilled?
Definition
Hydrostatic pressure could cause the cylinder to explode.
Term
List three methods for measuring the fill level of a recovery cylinder.
Definition
Floats, thermistor type sensors, and weighing scales.
Term
Wow often must reusable cylinders be hydrostatically tested?
Definition
Every five years.
Term
Why must only refillable cylinders be used for transport?
Definition
Federal code of regulations title 49 (parts 100-177) states this.
Term
What must be affixed to a refrigerant cylinder prior to its shipment to a reclaimer?
Definition
DOT classification tag.
Term
What is the purpose of a DOT classification tag?
Definition
For transportation purposes.
Term
What is the correct shipping position for a refrigerant cylinder?
Definition
In a vertical or upright position with their valves at the top.
Term
What is the EPA definition of a small appliance?
Definition
Appliances typically charged at the factory with five pounds or less of refrigerant. Refrigerators and freezers designed for home use, room air conditioners, including window and PTAC units, package heat pumps, dehumidifiers, under the counter ice makers, vending machines and drinking water coolers.
Term
Does the EPA require the repair of leaks on small appliances?
Definition
Repair of leaks on small appliances is not required, but leaks should be repaired whenever possible.
Term
What EPA certification type must technicians have to service any appliance that EPA calls a "small appliance?"
Definition
Type 1 or Universal.
Term
What service aperture may be used on small appliance?
Definition
Access tubes or process tubes.
Term
What is the name for a fitting, used to connect a recovery device to an appliance, which can close to prevent loss of refrigerant form hoses?
Definition
Low-loss fitting. (shut-off valve)
Term
What is the primary purpose for using hand valves or self-sealing hoses when using a gauge set?
Definition
To prevent loss of refrigerant.
Term
Which refrigerants must be recovered under Section 608 of the EPA regulations?
Definition
CFC, HCFC and HFC refrigerant.
Term
Is there a "drop-in" refrigerant for CFC-12?
Definition
No.
Term
What is the replacement refrigerant for CFC-12 in household refrigerators?
Definition
HFC-134a.
Term
What can be determined by taking an accurate temperature and pressure reading of a container holding a recovered refrigerant?
Definition
Check for non-condensables and the type of refrigerant.
Term
When doing a non-condensables check, a recovery cylinder should stabilize in temperature before any readings are taken. Why?
Definition
To find the correct pressure for that temperature on a T/P chart.
Term
What is the internal pressure of CFC-12 refrigerant stored at 75 deg. F?
Definition
77 PSIG.
Term
What is the exception to the rule that says that someone servicing and appliance must have at least one self-contained recovery machine available at their place of business?
Definition
Only when the person is working on a small appliance.
Term
Ammonia, hydrogen, and water can be found in the refrigerators in some campers and other recreational vehicles. Should these compounds be recovered with EPA approved recovery equipment?
Definition
No.
Term
May the nitrogen used for purging or pressurizing a system be vented to the atmosphere?
Definition
Yes.
Term
When may a technician recover only 80% of the refrigerant in a small appliance?
Definition
In a system dependent recovery with a non-operating compressor?
Term
May a technician use a passive recovery machine for recovery from a domestic refrigerator?
Definition
Yes.
Term
What requirements are placed on recovery machines built after November 15, 1993?
Definition
Must be able to recover 80% of the refrigerant if the compressor is inoperative or 90% if the compressor is operative. Must be EPA certified.
Term
When using a recovery machine manufactured after November 15, 1993, what percentage of the refrigerant must be recovered in a household refrigerator with an operating compressor? What percentage if the compressor is NOT operating?
Definition
80%, 90%.
Term
Is a certified technician responsible for future changes in EPA regulations?
Definition
Yes.
Term
What type of certification is required to purchase CFC and HCFC refrigerants?
Definition
Type 1.
Term
What must be done with any regulated refrigerant vented from a graduated charging cylinder?
Definition
It must be recovered.
Term
What first step must you always take before starting a recovery of refrigerant form any equipment?
Definition
Check which refrigerant is being used.
Term
What is a "system-dependent" recovery machine?
Definition
System dependent recovery machines rely on the compressor of the system being serviced, or the pressure of the refrigerant to pump the refrigerant into a recovery drum.
Term
Describe a system-dependent (passive) recovery process for small appliances.
Definition
Evacuate or cool a cylinder. Connect the high and low hoses to the system. Pull refrigerant into the cylinder with vacuum or the low tank pressure.
Term
What two conditions require that you access both the high and low side of the system for refrigerant recovery?
Definition
When there is an inoperative compressor on the system or when necessary to reach required recovery levels.
Term
What are the benefits of accessing the low and high side access valves when recovering refrigerant from a system with an inoperative compressor?
Definition
It speeds up recovery, improves efficiency and may be necessary to reach required recovery levels.
Term
How should you access the system and should you run the compressor when using a system-dependent (passive) recovery on a refrigerator with an operable compressor?
Definition
Access the high side and run the compressor.
Term
Which access valve (s) should you connect to when recovering from a system with an operating compressor and a completely restricted capillary tube?
Definition
High side valve.
Term
When using a self-contained (active) recovery device, what two conditions can cause excessive pressure on the recovery machine's high side?
Definition
A recovery container that is not properly evacuated or one that has unopened valve.
Term
Why should defrost heaters be turned on during a recovery from a small appliance?
Definition
To speed up refrigerant release from the oil.
Term
When should entrapped refrigerant from oil be recovered?
Definition
Any time oil is removed from a large system and on small appliances when using system dependent recovery with a non-operating compressor.
Term
What does striking the appliance compressor do during a recovery?
Definition
Helps to free refrigerant that may be trapped in the oil.
Term
A recovery machine should be checked daily for what?
Definition
Refrigerant leaks.
Term
Can a standard vacuum pump be used as a recovery machine?
Definition
In theory yes, but unlikely. First it would have to be certifiable, second it would have to be connected to a non-pressurized recovery container.
Term
Should technicians ever mix refrigerants in the field?
Definition
No.
Term
How should you recover refrigerant that is different from the refrigerant you usually recover?
Definition
Different refrigerants must be placed in recovery vessels containing the same type of refrigerant.
Term
What can a reclaimer do with any mixed refrigerant you ship to them?
Definition
They may either refuse to process and return it at owner's expense or agree to destroy the refrigerant for a substantial fee.
Term
To ship recovered refrigerant you must label the container and complete all necessary paperwork. What else should you do?
Definition
Use DOT approved cylinders.
Term
What federal agency sets the standards for portable refillable tanks or containers used to ship CFC or HCFC refrigerants?
Definition
Department of Transportation (DOT).
Term
Safety glasses and butyl-lined gloves should be worn fro what procedures?
Definition
When you are connecting and disconnecting hoses.
Term
Piercing valves are used for what purpose?
Definition
To allow access to the sealed system for recovery.
Term
On what materials are piercing valves used?
Definition
Copper or aluminum refrigerant lines.
Term
What should be done to a piercing type Schrader valve after it is installed on a charged system?
Definition
It should be capped after any service procedure.
Term
Why should solder-less type piercing valves be removed after completion of repairs?
Definition
To prevent leaks.
Term
What are the critical maintenance checks done to a Schrader valve?
Definition
Periodically checked for leaks and replaced if damaged.
Term
What does a pungent odor detected after opening a system mean?
Definition
It might mean acids are present due to a compressor burnout.
Term
What do you do if the oil is contaminated?
Definition
Tubing flushing might be required.
Term
What system pressure would indicate a recovery should not be performed?
Definition
0 PSIG.
Term
What are the current methods used to monitor the 80% fill level in a recovery tank?
Definition
Floats, thermistor-type sensors and weighing scales.
Term
Why do large refrigerant leaks cause suffocation?
Definition
Refrigerants will replace air in a confined space leading to possible oxygen starvation.
Term
Before entering an area of a large leak of refrigerant what apparatus must be worn?
Definition
Self contained breathing apparatus.
Term
What should be done if a large leak occurs and no breathing apparatus is available?
Definition
Ventilate the space and leave the area.
Term
Which acids are formed when refrigerant touches sources of high heat?
Definition
Hydrochloric and hydrofluoric acids and phosgene gas.
Term
What safety component must be used whenever dry nitrogen is used to pressurize a system?
Definition
Nitrogen tanks should be equipped with a regulator.
Term
What information does DOT require when shipping refrigerant cylinders?
Definition
Shipping papers must indicate the refrigerant type and number of cylinders.
Term
Which government agency sets the standards for refillable refrigerant cylinders used to transport CFC and HCFC refrigerants?
Definition
Department of Transportation (DOT).
Term
What component is always replaced after a a system is opened for service?
Definition
Filter-driers.
Term
What is the purpose of the moisture indicator in a sight glass?
Definition
To permit a check of moisture content in the system.
Term
What does "back-seating" a suction valve do?
Definition
Allows flow through the main line while closing the access port.
Term
What will non-condensables do to the pressures in a refrigerant circuit?
Definition
Increase discharge pressure.
Term
What causes oil foaming in a system and where does it normally occur?
Definition
Oil that is mixed with refrigerant will foam in the compressor crankcase.
Term
What system failures require taking an oil sample?
Definition
Compressor burnout or if the unit has had a leak.
Term
A vacuum pump that is too large can cause what problem?
Definition
It can cause moisture to freeze in the system?
Term
Where is a receiver typically installed on a system?
Definition
At the outlet of the condenser.
Term
What will be the boiling temperature of HFC-134a be at 0 PSIG?
Definition
-15 degrees F.
Term
Is it a requirement that recovery machines contain an oil separator?
Definition
No.
Term
Which refrigerant is typically used on a residential split system air conditioner?
Definition
HCFC-22.
Term
Is the refrigerant leaving a receiver a liquid or a gas? Is it at a high or low pressure?
Definition
Liquid, high pressure.
Term
What is the initial charging method of a system when the charge is specified at 70 pounds?
Definition
Charged in liquid state.
Term
Is the receiver on the high or low side of a system?
Definition
High side.
Term
What is the minimum recommended capability (measured in microns) of a vacuum pump used for evacuations?
Definition
Should pull a vacuum of 500 microns.
Term
What is the pressure of a CFC-12 machine at 72 deg. F while the machine is idle?
Definition
73 PSIG.
Term
What is the preferred unit of measurement for checking a deep vacuum?
Definition
Microns.
Term
Where is an accumulator located in a refrigeration system?
Definition
On the suction line before the compressor.
Term
To prevent freezing of any moisture in a CFC-12 system, vapor should first be charged until the pressure is at what level?
Definition
33 PSIG
Term
What gas should be used during an evacuation to increase pressure to prevent freezing?
Definition
Dry nitrogen.
Term
What is the purpose of a compressor heater?
Definition
To reduce the amount of refrigerant in the lubricating oil.
Term
How is moisture remaining from an evacuation removed from the refrigerant in a system?
Definition
By the filter-drier.
Term
What is the preferred method of leak checking a built-up system prior to charging?
Definition
Bubble solution.
Term
What would a technician initially look for during a visual inspection of a leaking hermetic system?
Definition
Stains around tubing and fittings.
Term
What is typically indicated by excessive superheat on a high-pressure system?
Definition
Undercharged system, possibly the result of a leaky system.
Term
Which refrigerant should be used for a trace charge during leak detection?
Definition
R-22.
Term
How do you leak check an HFC-134a system with a partial charge (no HFC-134a detector available)?
Definition
Recover remaining 134a, pressurize the system with nitrogen and a trace charge of R-22 so you can use an HCFC electronic leak detector.
Term
For what purpose are soap bubbles used in leak checking?
Definition
For a visual check for leaks.
Term
Shaft seals on an open type compressor are susceptible to what failures?
Definition
Refrigerant leaks.
Term
What leak rate is permissible on industrial and process refrigeration?
Definition
Effective 6/14/93, any leak rate of 35% or more on equipment with 50 lbs. of charge or more must be repaired. Less than 35% is permissible.
Term
What leak rate is permissible on equipment (other than industrial or process equipment) that contains more that 50 lbs. of refrigerant?
Definition
Less than 15% annually.
Term
What is the easiest way to check the type of refrigerant used in a packaged rooftop system?
Definition
By the equipment data plate.
Term
Refrigerant will recover fastest in which phase, liquid or vapor?
Definition
Liquid.
Term
Which refrigerant line should a recovery machine be attached to in order to recover liquid refrigerant from a system?
Definition
To the liquid line.
Term
After a liquid recovery, what must be done with the vapor still in the system?
Definition
Vapor recovery bust be performed.
Term
Recovering in a vapor phase reduces unwanted loss of what?
Definition
Oil and unwanted contaminants from the system to the recovery machine and recovery drum.
Term
On a high pressure system recovery, should the recovery cylinder be heated or cooled?
Definition
Cooled.
Term
What must be done to a recovery machine when changing to a different refrigerant?
Definition
Clean out all residual refrigerant, change oil, replace filters, evacuate machine by pump-out or another machine.
Term
What besides filters must periodically be changed out on a recovery machine?
Definition
Oil.
Term
Recovered refrigerant can contain oil and acids. Name another compound found in refrigerants?
Definition
Moisture.
Term
What is the water source for a condensing coil on a water-cooled recovery machine?
Definition
Municipal water tap.
Term
What access location should you use when recovering from an air cooled system with its condenser several feet above the evaporator?
Definition
Suction line.
Term
What access location should you use when recovering from a system with its condenser below the evaporator?
Definition
Liquid line.
Term
Before using a recovery unit, the technician should check service valve positions and check the recovery unit oil level. What additional step must be taken?
Definition
All solenoid valves should be open.
Term
What is the primary purpose for using hand valves or self-sealing hoses when using a gauge set?
Definition
To prevent loss of refrigerant when connecting and disconnecting hoses.
Term
What can cause recovery equipment with a hermetic compressor to overheat when drawing a deep vacuum?
Definition
No airflow over the compressor body or no suction gas flow over the internal motors, or a combination of the two.
Term
What is the reason for not operating a hermetic refrigeration compressor while it is in a deep vacuum?
Definition
To prevent overheating the compressor motor.
Term
What is the reason for not starting a reciprocating compressor with its discharge service valve closed?
Definition
To prevent overheating the compressor motor.
Term
When can a "system-dependent" recovery device be used?
Definition
On small appliances as long as the device meets EPA standards and the technician adheres to the servicing procedures specified for the recovery equipment. Cannot be used on systems with more than 15 lbs. of refrigerant.
Term
What vacuum level must you reach when recovering from a system with 38 pounds of R-502 using a recovery machine manufactured in 1995?
Definition
10 inches of Hg.
Term
What is EPA's definition of a "major repair"?
Definition
Any repair that involves the removal of the compressor, evaporator, condenser, or any auxiliary heat exchanger coil.
Term
Prior to making a major repair, what vacuum level must you pull when using recovery equipment manufactured in 1996 on a unit with 215 lbs. of CFC-12?
Definition
15 inches of Hg.
Term
What vacuum level must you pull when using recovery equipment manufactured in 1992 when disposing of an appliance containing 12 lbs. of R-500?
Definition
4 inches of Hg.
Term
Under what circumstances may a technician recover the CFC refrigerant in an appliance to atmospheric pressure only?
Definition
if leaks are in the system or if recovery to target levels would contaminate the refrigerant.
Term
What procedure should be performed on an empty recovery cylinder before it is used for storing recovered refrigerant?
Definition
It must be evacuated of all non-condensables.
Term
What may legally be done with the refrigerant recovered from a system in order to replace a condenser coil?
Definition
Reused in the original system or transferred to another system with the same owner after it is checked so that it is free of non-condensables.
Term
When servicing an operating unit with a receiver, where should the recovery hoses be attached to the unit?
Definition
To the liquid line.
Term
In order to recover from a system with parallel compressors, the individual compressors must be isolated. Why?
Definition
It isolates the refrigerant that must be recovered from the rest of the system.
Term
Which refrigerant (s) require and equipment room monitor per ASHRAE Standard 15?
Definition
All refrigerants.
Term
What protection is mandatory to protect a system against damage from excessive pressure?
Definition
A pressure relief device.
Term
Are multiple relief valves connected in series or parallel?
Definition
Parrallel.
Term
Why is the use of a regulator required when using dry nitrogen?
Definition
To limit the outlet pressure of the nitrogen cylinder.
Term
How can ice be removed from a sight glass?
Definition
Cleaned with an alcohol spray.
Term
How high should you pressurize an idle low pressure chiller to prevent air accumulation?
Definition
Slightly above atmospheric pressure.
Term
What effect does air in a chiller have on head pressure?
Definition
Raises head pressure.
Term
What system failures require taking and oil sample?
Definition
A leak or major component failure (compressor burnout).
Term
Why must water be circulated through a chiller during refrigerant recovery?
Definition
To prevent freeze-up of the water as pressure is reduced on the refrigerant.
Term
What is the lowest access valve on a low pressure chiller?
Definition
The evaporator charging valve.
Term
Where is a centrifugal chiller's rupture disk attached?
Definition
At the evaporator.
Term
What is the typical pressure setting for a low pressure chiller's rupture disk?
Definition
15 PSIG.
Term
Where is the outlet of a rupture disk discharged?
Definition
Outdoor for venting.
Term
How is a chiller typically charged?
Definition
Liquid through the evaporator charging valve.
Term
What minimum saturation temperature needs to be achieved before liquid is charged into a chiller?
Definition
Above freezing, typically 36 deg. F.
Term
To prevent freezing of water when charging a chiller, what pressure should be reached with vapor before using liquid CFC-11?
Definition
16.9 inches of Hg.
Term
What could result from liquid refrigerant being charged into a chiller that is holding a 29 inch Hg. vacuum?
Definition
Can cause system water to freeze.
Term
What function is served by a purge unit on a chiller?
Definition
Minimize the effects of contamination. To remove non-condensables.
Term
What is the most likely cause of air leaks into a chiller refrigerant circuit?
Definition
Gaskets and fittings.
Term
How is a purge unit connected on a low pressure chiller?
Definition
The inlet of the purge unit is typically connected to the top of the condenser.
Term
Where is the suction of a purge unit connected?
Definition
The inlet of the purge unit is typically connected to the top of the condenser.
Term
What is a high efficiency purge unit?
Definition
It removes non-condensables that contain a low percentage of refrigerant. This adds to the value of the purge drum in refrigerant containment.
Term
Shaft seals on an open type compressor are susceptible to what failures?
Definition
Refrigerant leaks.
Term
Purge units work best when they are not needed. How can purge unit operating time be reduced?
Definition
By regular leak checking and repairing any leaks on a regular schedule.
Term
What is the maximum pressure that can be used when leak checking a low pressure chiller?
Definition
10 PSIG on low pressure equipment that utilizes a rupture disk.
Term
What is the preferred method of leak checking a charged low pressure chiller?
Definition
By increasing the refrigerant pressure using an external heat source or running hot water through the chiller tubes not to exceed 10 PSIG.
Term
Where should you check for leaks between a chiller refrigerant tube and the water box?
Definition
The chiller barrel can be emptied of all water and a leak check can be made at the drain valve with the water off. If the tubes themselves require a leak check, the check can be made with a hydrostatic tube test kit.
Term
What is a hydrostatic tube test kit used for?
Definition
To check for leaks in a chiller tubes.
Term
What leak rate is permissible on industrial and process refrigeration?
Definition
Effective 6/14/93, any annualized leak rate of 35% or more on equipment with 50 lbs. of charge or more must be repaired. Less than 35% is permissible.
Term
What leak rate is permissible on equipment other than industrial and process equipment?
Definition
For appliances with 50 lbs. of charge or more an annual leak rate of 15% or more must be repaired. Less than 15% leak rate is permissible.
Term
According to ASHRAE 3-1990, what rise is permitted in vacuum level during a standing vacuum test?
Definition
Starting at 1mm of Hg., after 12 hours the vacuum reading should not increase to more than 2.5 mm of Hg.
Term
List two steps to reduce the run time of a purge unit.
Definition
Regular leak checks and repair any leaks.
Term
Why should the water side of the evaporator and condenser be drained before recovering refrigerant from a chiller suspected of having tube leaks?
Definition
To prevent moisture form being drawn into the refrigerant circuit.
Term
If a purge unit is operating excessively, what problem can you expect to find?
Definition
Leaks.
Term
What condition would cause continuous excessive moisture collection in the purge unit of a low pressure refrigeration system?
Definition
Leaks between the refrigerant circuit and the water circuit.
Term
Why should oil be warmed prior to removal from a low pressure chiller?
Definition
To vaporize any liquid refrigerant that might be trapped in the oil.
Term
After liquid recovery, what must be done with the vapor still in the system?
Definition
Vapor recovery must be performed.
Term
Is recovery of refrigerant from a low pressure appliance typically started with liquid or vapor?
Definition
Start with liquid removal.
Term
Where is the connection made for the water supply used on a water cooled recovery unit?
Definition
Local water supply.
Term
What should be the maximum pressure on the discharge of a recovery machine for low pressure systems?
Definition
10 PSIG, because the rupture disk is set to open at 15 PSIG.
Term
What should be done with the water pumps during a recovery form a low pressure chiller?
Definition
Term
What is EPA's definition of a "major repair"?
Definition
Any repair that involves the removal of the compressor, evaporator, condenser, or any auxiliary heat exchange coil.
Term
What recovery vacuum must be met on a low pressure appliance using a machine built in 1992?
Definition
25 inches of Hg.
Term
Why should you wait a few minutes after reaching the required recovery vacuum on an appliance to see if pressure rises?
Definition
To see if refrigerant is still trapped in the system.
Term
Under what circumstances may the recovery from an appliance be stopped without reaching the prescribed level?
Definition
If the recovery would contaminate the refrigerant being recovered. (this level cannot exceed 0 PSIG.)
Term
Is it a requirement that recycling and recovery equipment be capable of handling more than one refrigerant?
Definition
No.
Term
Is it permissible to warm the refrigerant under EPA's regulations to pressurize a low pressure system to do a non-major repair?
Definition
Yes.
Term
What final vacuum level is required for recovering refrigerant from a low pressure system if the technician is using recovery equipment manufactured BEFORE November 15, 1993? AFTER November 15, 1993?
Definition
25 inches of Hg, 25 mm of Hg. Absolute (equal to about 29 inches of Hg.)
Term
A vacuum pump that is too large for a particular system can cause what problem?
Definition
It can cause moisture to freeze in the system.
Term
How can you prevent moisture from freezing during dehydration?
Definition
You can raise the pressure with nitrogen and allow the ice to melt, then continue with the evacuation.
Term
Are multiple relief valves connected in series or parallel?
Definition
Parallel.
Term
ASHRAE Standard 15 covers refrigerant level monitoring for what refrigerants?
Definition
All refrigerants.
Term
According to ASHRAE Standard 15, what is the standard for refrigerant concentration for a machine room that must not be exceeded without activating an alarm and starting ventilation in the machine room?
Definition
May not exceed the TLV-TWA. (Threshold limit value-Time weighted average.)
Term
List four safety procedures that should be followed when working with liquid low pressure refrigerant.
Definition
1. Use refrigerant sensors in equipment room.
2. Avoid siphoning refrigerant by mouth.
3. Wear butyl-lined gloves.
4. Wear safety glasses.
Term
What is the toxicity and flammability rating of HCFC-123 per ASHRAE Standard 34?
Definition
B1.