refrigeration2

Card Set Information

Author:
pegwinn
ID:
61564
Filename:
refrigeration2
Updated:
2011-01-24 00:21:31
Tags:
Fundamentals PQS Refrigeration UPOII
Folders:

Description:
Refrigeration II for UPOII
Show Answers:

Home > Flashcards > Print Preview

The flashcards below were created by user pegwinn on FreezingBlue Flashcards. What would you like to do?


  1. DESCRIBE THE FOLLOWING TERM AS APPLIED TO REFRIGERANTS AND THE ENVIRONMENT: Ozone
    (O3 three oxygen atoms) Ozone is a bluish gas that is harmful to breathe. Nearly 90% of the Earth's ozone is in the stratosphere and is referred to as the ozone layer. Ozone absorbs a band of ultraviolet radiation called UVB that is particularly harmful to living organisms. The ozone layer prevents most UVB from reaching the ground. The ozone layer lies approximately 15-40 kilometers (10-25 miles) above the Earth's surface, in the stratosphere.
  2. DESCRIBE THE FOLLOWING TERM AS APPLIED TO REFRIGERANTS AND THE ENVIRONMENT: Recover
    Removing refrigerant in any condition from a system in either active, or a passive manner, and storing it in an external container without necessarily testing or processing it in any way.
  3. DESCRIBE THE FOLLOWING TERM AS APPLIED TO REFRIGERANTS AND THE ENVIRONMENT: Recycle
    Recycling means the use of a machine to remove impurities and oil and then recharge the refrigerant into either the same system or a different system. Recycled refrigerant is not as pure as reclaimed refrigerant.
  4. DESCRIBE THE FOLLOWING TERM AS APPLIED TO REFRIGERANTS AND THE ENVIRONMENT: Reclaim
    Reclamation means the removal of all oil and impurities beyond that provided by on-site recycling equipment, and reclaimed refrigerant is essentially identical to new, unused refrigerant. Reclamation cannot be performed in the service shop. Rather, the shop generally sends refrigerant either back to the manufacturer or directly to a reclamation facility.
  5. DESCRIBE THE FOLLOWING TERM AS APPLIED TO REFRIGERANTS AND THE ENVIRONMENT: Appliance
    Any device, which contains and uses class I (CFC) or II HCFC) substance as a refrigerant and is used for household or commercial purpose. Air conditioner, refrigerator, chiller, freezer regardless of size. Equipment for industrial process refrigeration.
  6. DESCRIBE THE FOLLOWING TERM AS APPLIED TO REFRIGERANTS AND THE ENVIRONMENT: Small appliance
    A system manufactured, charged and hermetically sealed with 5 lbs or less of refrigerant.
  7. DESCRIBE THE FOLLOWING TERM AS APPLIED TO REFRIGERANTS AND THE ENVIRONMENT: Major repair
    A repair that involves removal of the compressor, evaporator, condensers, or any auxiliary heat exchanger coil.
  8. DESCRIBE THE FOLLOWING TERM AS APPLIED TO REFRIGERANTS AND THE ENVIRONMENT: Miscibility
    The ability of one liquid to mix with (dissolve in) another liquid. Think of miscibility as 'mixability' and it's easy to remember. Fluid volumes (liquids and gases) aren't necessarily additive. Intermolecular forces (hydrogen bonding, London dispersion forces.
  9. DESCRIBE THE FOLLOWING TERM AS APPLIED TO REFRIGERANTS AND THE ENVIRONMENT: Hygroscopicity
    That property of a substance, which enables it to absorb water vapor from the surrounding atmosphere. Relative to most materials, vellum and paper, particularly the former, are strongly hygroscopic. One of the last things you want in a refrigeration system is moisture. Moisture causes lubrication breakdown and can cause ice to form at low pressure points. Moisture re-acts with the refrigerant to create acid as a by-product. Acid attacks components and motor windings - and generally shortens the life of the compressor. ERG 500 is virtually non-hygroscopic; it carries no moisture into the system.
  10. DESCRIBE THE FOLLOWING TERM AS APPLIED TO REFRIGERANTS AND THE ENVIRONMENT: De minimis
    Quantities of refrigerant released in the course of making good faith attempts to recapture and recycle or safely dispose of refrigerant.
  11. STATE/DESCRIBE THE METHODS OF REFRIGERANT RECOVERY:
    • a. Self-contained recovery: Built into the system.
    • b. System dependent recovery: Needs a separate unit to recover the refrigerant.
    • c. Push-pull method: Using the pump down unit to put pressure in the system to push refrigerant, and pull it down from the compressor and evaporator.
    • d. Liquid recovery: Allowing gravity and pressure supplied to the system when putting flow through the evaporator, to move the liquid in the cooler/evaporator.
    • e. Vapor recovery: Using/applying pressure in the system to move the vapor to the storage tank.
  12. EXPLAIN HOW CHLORINE CONTAINING COMPOUNDS DESTROY THE OZONE LAYER.
    One chlorine molecule can destroy approximately 1,000,000 ozone molecules. They drift to the stratosphere. The chlorine then reacts with the ozone, changing it back to oxygen O2.
  13. DESCRIBE THE FOLLOWING ENVIRONMENTAL IMPACTS AND THE FACTORS THAT AFFECT THEM:
    Global warming: The progressive gradual rise of the earth's surface temperature thought to be caused by the greenhouse effect and responsible for changes in global climate patterns. An increase in the near surface temperature of the Earth. Global warming has occurred in the distant past as the result of natural influences, but the term is most often used to refer to the warming predicted to occur as a result of increased emissions of greenhouse gases.
  14. DESCRIBE THE FOLLOWING ENVIRONMENTAL IMPACTS AND THE FACTORS THAT AFFECT THEM:
    Ozone depletion: Chemical destruction of the stratospheric ozone layer beyond natural reactions. CFCs release chlorine atoms, and halons release bromine atoms. It is these atoms that actually destroy ozone, not the intact ODS molecule. It is estimated that one chlorine atom can destroy over 100,000 ozone molecules before finally being removed from the stratosphere.
  15. DESCRIBE THE CHARACTERISTICS OF THE FOLLOWING ALTERNATE REFRIGERANTS: Blends
    Refrigerant blends are mixtures of refrigerant that have been formulated to provide similar pressure/temperature relationship to the original refrigerant. Blends can be HCFC based, HFC based, or a combination of both. The HCFC-based blends are only interim CFC replacements because of their non-zero ODP.
  16. DESCRIBE THE CHARACTERISTICS OF THE FOLLOWING ALTERNATE REFRIGERANTS: Azeotropes
    A mixture made up of two or more refrigerants with similar boiling points that act as a single fluid. The components of azeotropic mixtures will not separate under normal operating conditions and can be charged as a vapor or liquid.
  17. DESCRIBE THE CHARACTERISTICS OF THE FOLLOWING ALTERNATE REFRIGERANTS: Zeotropes
    A mixture made up of two or more refrigerants with different boiling points. Zeotropic mixtures are similar to near-azeotropic mixtures with the exception of having a temperature glide greater than 10° F. Zeotropic mixtures should be charged in the liquid state.
  18. DESCRIBE THE CHARACTERISTICS OF THE FOLLOWING ALTERNATE REFRIGERANTS: Near azeotropic
    A mixture made up of two or more refrigerants with different boiling points that, when in a totally liquid or vapor state, act as one component. However, when changing from vapor to liquid or liquid to vapor, the individual refrigerants -evaporate or condense at different temperatures. Near-azeotropic mixtures have a temperature glide (see below) of less than 10° F and should be charged in the liquid state to assure proper mixture (non-azeotropic) composition.
  19. EXPLAIN THE REQUIREMENTS FOR MACHINERY SPACE MONITORS AS STATED IN ANSI/ASHRAE 15-1992.
    • All refrigerants have an allowable exposure limit (AEL) and threshold limit value (TLV). Heavier-than-air refrigerants can concentrate at floor levels and displace breathable oxygen. In ASHRAE Standard 15-1992, 7.4 System Application Requirements specifies the allowable limits on refrigerant amounts. ASHRAE Standard 15-1992 - Safety Code for Mechanical Refrigeration - specifies maximum permissible quantities of refrigerants. From a safety-monitoring standpoint, the refrigerant amount is unlimited when, along with other requirements, detectors are located in areas where refrigerant vapor from a leak is likely to concentrate to provide an alarm at the following levels:
    • Safety Group A1 (>400 ppm TLV low toxicity) refrigerants, such as HFC-134a and HCFC-22, alarms should provide warning at below 19.5% volume oxygen. Safety Group B1 (higher toxicity) refrigerants, such as HCFC-123, alarms should provide warning at no higher than their TLV (or toxicity measure consistent therewith).
    • With HCFC-123, due to its lower AEL and TLV (currently 10 ppm AEL and TLV) than conventional refrigerants, adequate equipment room ventilation must be verified.
  20. WHAT IS THE CLEAN AIR ACT OF 1990? DESCRIBE SECTION VI OF THIS ACT.
    • Section VI of the act (Stratospheric Ozone Protection) November 15th 1990. President Bush singed into law. Regulating recycling repair and disposal of CFC’s and HCFC’s. Prohibiting releasing, ozone depleting chemicals to the atmosphere.
    • (a) By not later than January 1, 1992, promulgate regulations establishing standards and requirements regarding the use and disposal of class I substances during the service, repair, or disposal of appliances and industrial process refrigeration. Such standards and requirements shall become effective not later than July 1, 1992. Reduce the use and emission of such substances to the lowest achievable level, and maximize the recapture and recycling of such substances. Such regulations may include requirements to use alternative substances (including substances, which are not class I or class II substances) or to minimize use of class I or class II substances, or to promote the use of safe alternatives pursuant to section 612 or any combination of the foregoing.
    • (b) SAFE DISPOSAL.-The regulations under subsection (a) shall establish standards and requirements for the safe disposal of class I, and II substances.
    • (c) PROHIBITIONS.-(1) Effective July 1, 1992, it shall be unlawful for any person, in the course of maintaining, servicing, repairing, or disposing of an appliance or industrial process refrigeration, to knowingly vent or otherwise knowingly release or dispose of any class I or class II substance used as a refrigerant in such appliance (or industrial process refrigeration) in a manner which permits such substance to enter the environment.
  21. WHAT DOES FEDERAL LAW STATE CONCERNING THE FOLLOWING:Certification
    Divided into 4 classes Type I (small appliance), Type II (high pressure), Type III (low pressure), Type IV (universal). Must be certified to service maintain, and repair air conditioning and refrigerant equipment.
  22. WHAT DOES FEDERAL LAW STATE CONCERNING THE FOLLOWING: Venting
    • Effective July 1, 1992, Section 608 of the Act prohibits individuals from knowingly venting ozone-depleting compounds (generally CFCs and HCFCs) used as refrigerants into the atmosphere while maintaining, servicing, repairing, or disposing of air-conditioning or refrigeration equipment (appliances). Only four types of releases are permitted under the prohibition:
    • 1. "De minimis" quantities of refrigerant released in the course of making good faith attempts to recapture and recycle or safely dispose of refrigerant.
    • 2. Refrigerants emitted in the course of normal operation of air-conditioning and refrigeration equipment (as opposed to during the maintenance, servicing, repair, or disposal of this equipment) such as from mechanical purging and leaks. However, EPA requires the repair of leaks above a certain size in large equipment (see Refrigerant Leaks).
    • 3. Releases of CFCs or HCFCs that are not used as refrigerants. For instance, mixtures of nitrogen and R-22 that are used as holding charges or as leak test gases may be released, because in these cases, the ozone-depleting compound is not used as a refrigerant. However, a technician may not avoid recovering refrigerant by adding nitrogen to a charged system; before nitrogen is added, the system must be evacuated to the appropriate level in Table 1. Otherwise, the CFC or HCFC vented along with the nitrogen will be considered a refrigerant. Similarly, pure CFCs or HCFCs released from appliances will be presumed to be refrigerants, and their release will be considered a violation of the prohibition on venting.
    • 4. Small releases of refrigerant that result from purging hoses or from connecting or disconnecting hoses to charge or service appliances will not be considered violations of the prohibition on venting. However, recovery and recycling equipment manufactured after November 15, 1993, must be equipped with low-loss fittings
  23. WHAT DOES FEDERAL LAW STATE CONCERNING THE FOLLOWING: Recovery equipment certification:
    • Required to have an EPA approved certification label.
    • Equipment Certification. Equipment manufactured before November 15, 1993, including home-made equipment, may be grandfathered if it meets the standards in the first column of Table 1. Third-party testing is not required for equipment manufactured before November 15, 1993, but equipment manufactured on or after that date, including home-made equipment, must be tested by a third-party.
    • The Agency has established a certification program for recovery and recycling equipment. Under the program, EPA requires that equipment manufactured on or after November 15, 1993, be tested by an EPA-approved testing organization to ensure that it meets EPA requirements. Recycling and recovery equipment intended for use with air-conditioning and refrigeration equipment besides small appliances must be tested under the ARI 740-1993 test protocol, which is included in the final rule as Appendix B. Recovery equipment intended for use with small appliances must be tested under either the ARI 740-1993 protocol or Appendix C of the final rule.
    • The Agency requires recovery efficiency standards that vary depending on the size and type of air-conditioning or refrigeration equipment being serviced. For recovery and recycling equipment intended for use with air-conditioning and refrigeration equipment besides small appliances, these standards are the same as those in the second column of Table 1. Recovery equipment intended for use with small appliances must be able to recover 90 percent of the refrigerant in the small appliance when the small appliance compressor is operating and 80 percent of the refrigerant in the small appliance when the compressor is not operating.
    • EPA has approved both the Air-Conditioning and Refrigeration Institute (ARI) and Underwriters Laboratories (UL) to certify recycling and recovery equipment. Certified equipment can be identified by a label reading: "This equipment has been certified by ARI/UL to meet EPA's minimum requirements for recycling and/ or recovery equipment intended for use with [appropriate category of appliance--e.g., small appliances, HCFC appliances containing less than 200 pounds of refrigerant, all high-pressure appliances, etc.]." Lists of certified equipment may be obtained by contacting ARI at 703-524-8800 and UL at 708-272-8800 ext. 42371.
  24. WHAT DOES FEDERAL LAW STATE CONCERNING THE FOLLOWING: Manufacturing of CFC’s:
    Eliminate the manufacturing of CFC’s by 31 December 1995.
  25. REQUIRED EVACUATION LEVELSType of ApplianceHG < 11-15-93HG > 11-15-93
    HCFC-22 appliance < 200 lbs ref00
    HCFC-22 appliance > 200 lbs ref410
    Other HP appliance < 200 pounds of ref (CFC-12, -500, -502, -114)410
    Very HP Appliance (CFC-13, -503)00
    Low-Pressure Appliance (CFC-11, HCFC-123)2525 MM HG abs
  26. WHAT ARE THE REQUIRED EVACUATION LEVELS FOR SMALL APPLIANCES?
    • Technicians repairing small appliances, such as household refrigerators, window air conditioners, and water coolers, must recover:
    • 80 percent of the refrigerant when - the technician uses recovery or recycling equipment manufactured before November 15, 1993, or - the compressor in the appliance is not operating;
    • OR
    • 90 percent of the refrigerant when - the technician uses recovery or recycling equipment manufactured after November 15, and - the compressor in the appliance is operating
    • In order to ensure that they are recovering the correct percentage of refrigerant, technicians must use the recovery equipment according to the directions of its manufacturer. Technicians may also satisfy recovery requirements by evacuating the small appliance to four inches of mercury vacuum.
  27. DESCRIBE THE REQUIREMENTS FOR SYSTEM LEAK RATES AND REPAIRS.
    • The leak repair requirements, promulgated under Section 608 of the Clean Air Act Amendments of 1990, require that when an owner or operator of an appliance that normally contains a refrigerant charge of more than 50 pounds discovers that refrigerant is leaking at a rate that would exceed the applicable trigger rate during a 12-month period, the owner or operator must take corrective action.
    • Trigger Rates
    • For all appliances that have a refrigerant charge of more than 50 pounds, the following leak rates for a 12-month period are applicable:
    • commercial refrigeration 35%
    • industrial process refrigeration 35%
    • comfort cooling 15%
    • all other appliances 15%
    • Owners of equipment with charges of greater than 50 pounds are required to repair leaks in the equipment when those leaks together would result in the loss of more than a certain percentage of the equipment's charge over a year. For the commercial and industrial process refrigeration sectors, leaks must be repaired when the appliance leaks at a rate that would release 35 percent or more of the charge over a year. For all other sectors, including comfort cooling, leaks must be repaired when the appliance leaks at a rate that would release 15 percent or more of the charge over a year.
    • The trigger for repair requirements is the current leak rate rather than the total quantity of refrigerant lost. For instance, owners of a commercial refrigeration system containing 100 pounds of charge must repair leaks if they find that the system has lost 10 pounds of charge over the past month; although 10 pounds represents only 10 percent of the system charge in this case, a leak rate of 10 pounds per month would result in the release of over 100 percent of the charge over the year. To track leak rates, owners of air-conditioning and refrigeration equipment with more than 50 pounds of charge must keep records of the quantity of refrigerant added to their equipment during servicing and maintenance procedures.
    • Owners are required to repair leaks within 30 days of discovery. This requirement is waived if, within 30 days of discovery, owners develop a one-year retrofit or retirement plan for the leaking equipment. Owners of industrial process refrigeration equipment may qualify for additional time under certain circumstances. For example, if an industrial process shutdown is required to repair a leak, owners have 120 days to repair the leak. Owners of leaky industrial process refrigeration equipment should see the Compliance Assistance Guidance Document for Leak Repair (available from the hotline) for additional information concerning time extensions and pertinent record-keeping and reporting requirements. EPA anticipates putting this document on the web site, but does not have an estimated date for when that will happen.
  28. BY LAW, BRIEFLY DESCRIBE THE RESTRICTIONS, WHICH APPLY TO REFRIGERANT HANDLING LICENSING.
    • Technician Certification
    • EPA has established a technician certification program for persons ("technicians") who perform maintenance, service, repair, or disposal that could be reasonably expected to release refrigerants into the atmosphere. The definition of "technician" specifically includes and excludes certain activities as follows:
    • Included:
    • attaching and detaching hoses and gauges to and from the appliance to measure pressure within the appliance; adding refrigerant to or removing refrigerant from the appliance any other activity that violates the integrity of the MVAC-like appliances, and small appliances.
    • In addition, apprentices are exempt from certification requirements provided the apprentice is closely and continually supervised by a certified technician.
    • The Agency has developed four types of certification:
    • For servicing small appliances (Type I).
    • For servicing or disposing of high- or very high-pressure appliances, except small appliances and MVACs (Type II).
    • For servicing or disposing of low-pressure appliances (Type III)
    • For servicing all types of equipment (Universal).
    • Technicians are required to pass an EPA-approved test given by an EPA-approved certifying organization to become certified under the mandatory program. The Stratospheric Ozone Hotline distributes lists of approved testing organizations.
  29. DESCRIBE THE CHARACTERISTICS OF THE FOLLOWING TYPES OF REFRIGERANT LUBRICANTS:
    • a. Polyester (esters) : The most used lubricant for HFC-134a. A general term that applies to a family of synthetic refrigeration oils based on the chemistry of polyol esters. Ester oils are generally regarded as the oil to use with most of the alternative refrigerants. Ester oils are generally compatible with existing mineral oils, and system components. Ester oils are slightly hygroscopic and should be in non-porous containers.
    • b. Mineral oils: A natural oil. R-12 lubricant. Refrigeration oil currently in use but is not compatible with most of the alternative refrigerants.
    • c. Alkaline benzene: A synthetic refrigeration oil commonly known as Zerol. Used with some ternary blends.
    • Lubricant Compatibility
    • One of the most important system changes is the lubricant. The lubricant uses in a system should always be identified on the unit because of potential lubricant incompatibilities. The mineral oil lubricant used with R-12 systems will not mix with the polyalkylene glycol (PAG) or polyol ester (POE) lubricant used in R-134a systems. (As little as 1% mineral oil will contaminate a POE oil.) HFC-134a still carries some concern about compatible lubricants.
    • Polyalkylene glycols (PAGs) mix properly with HFC-134a at low temperatures but have upper-temperature problems, as well as incompatibility with aluminum bearings and polyester hermetic motor insulation. Ester-based synthetic, (POE), lubricants for HFC-134a resolve these problems but are incompatible with existing PAG or mineral oils
  30. DESCRIBE THE FOLLOWING TYPES OF LEAK DETECTION DEVICES: WHICH IS MOST ACCURATE?
    • a. Visual: This labor-intensive procedure is very time-consuming except for the largest, most obvious leaks. Some people lay newspaper down to try to locate the general area of the leak. They will check the color of the fluid to try to identify what system it is coming from, i.e., red for transmission fluid, green for coolant, etc. However, it’s often difficult to pinpoint the exact source. Cannot be used for refrigerant leaks or for small leaks, which evaporate right away. It’s difficult to detect for clear liquids.
    • b. Halide torch: This is a step up from bubble solutions. However, halide torches reveal only a limited number of leaking refrigerants. The method is based on the fact that the flame of a torch turns green when exposed to refrigerants containing chlorine atoms (CFCs and HCFCs).
    • c. Fluorescent: Fluorescent leak detection: With this method, a fluorescent dye is added to the air conditioning or refrigeration system. The dye mixes with the lubricant and circulates with the refrigerant throughout the system. Wherever the refrigerant leaks out, so does the dye.
    • The refrigerant evaporates, but the dye remains at every leak site. When the system is scanned with an ultraviolet (UV) or UV/blue light lamp, the dye glows a bright yellow-green color to pinpoint the exact location of even the smallest leaks. With the fluorescent leak detection method, the contractor should be sure to use an oem-approved dye that is compatible with the lubricant in the system. Also, it is best to select a UV or UV/blue light lamp that produces high-intensity output. The greater the light intensity, the brighter the dye glows, and the easier it is to find leaks.
    • d. Soap bubble: This is the simplest and probably the oldest and least-expensive method of leak detection. A soapy solution is applied at suspected leak points, usually with a squeeze bottle, brush, or dauber. The escaping refrigerant causes bubbles to develop.
    • e. Electronic halide: Electronic detectors (sniffers): There are two basic types that can be used to test for escaping refrigerant.
      • 1. Heated diode technology consists of a ceramic element that heats the refrigerant and breaks the molecule apart, leaving positively charged chlorine or fluorine ions which are attracted to a negatively charged center collection wire. The flow of chlorine/fluorine ions to the center collection wire creates a small current. As the concentration of refrigerant between the electrodes increases, the current increases to a level that sets off an audio-visual alarm.
      • 2. Corona suppression technology measures variations in the conductivity of gases passing between two electrodes. The instrument creates a high-voltage dc spark that jumps from one point to another in the sensor.
    • f. Ultrasonic: Using highly sensitive microphones, these ac- or battery-powered devices are the only detectors that “listen” for the high-pitched, inaudible sound of a leak, which sets off an audio-visual alarm. When selecting a leak detection method, the technician must consider system factors, environmental factors, and human factors.
    • g. Inert gas pressurization: Inert gas put in the system to find the leak. This way your not loosing/using refrigerant as a test agent.
    • h. Standing vacuum: Must maintain specific vacuum for specified time period as per the EPA chart.

What would you like to do?

Home > Flashcards > Print Preview