ASHRAE Guideline 3-1996
`(Supersedes ASHRAE Guideline 3-1990)
`
`Reducing Emission
`of Halogenated
`Refrigerants in
`Refrigeration and
`Air-Conditioning
`Equipment and
`Systems
`
`Approved by the ASHRAE Standards Committee
`June 21, 1996, and by the ASHRAE Board of
`Directors June 27, 1996.
`
`ASHRAE Guidelines are updated on a five-year
`cycle; the date following the Guideline number
`is the year of ASHRAE Board of Directors
`approval. The latest copies may be purchased
`from ASHRAE Customer Service, 1791 Tullie
`Circle, NE, Atlanta, GA 30329.
`
`©1996 American Society of Heating, Refrigerat-
`ing and Air-Conditioning Engineers, Inc. All
`rights reserved.
`
`ISSN 1049-894X
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`Arkema Exhibit 1106
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`Page 1 of 20
`
`

`
`ASHRAE STANDARD PROJECT COMMITTEE 147P FOR GUIDELINE 3-1996
`Cognizant TC: TC 3.8, Refrigerant Containment
`Standards Project Committee Liaison: Michael R. Bilderbeck
`
`Warren L. Beeton, Chair
`Van D. Baxter,* Secretary
`John G. Blackmon
`Joshua Donald Costell
`William S. de Laurier
`Richard J. Denny
`Jeff Dickson*
`Warren H. Dillenbeck
`Bryan Franklin
`Herbert T. Gi key
`Jeff S. James
`Henry A. Johnson
`Philip C. Landes
`Dean E. Lewis
`
`Debbie Ottinger*
`Jude A. Pauli
`Christopher M. Powers
`Robert Joseph Roth*
`Stephen V. Santoro*
`Amy L. Savage
`James I. Sheridan
`Sam P. Soling
`Leonard J. Swatkowski*
`William Vestal
`Ricardo Valles Vicuna*
`Richard Bowman Wimsatt*
`Robert W. Yost
`
`*Denotes members of voting status when Guideline 3-1990R was approved for publication.
`
`ASHRAE STANDARDS COMMITTEE 1995-96
`
`Max H. Sherman, Chair
`Sally A. Hooks, Vice-Chair
`Richard L. Beck, Jr.
`Herman F. Behls
`W. David Bevirt
`Michael R. Bilderbeck
`George F. Carscallen
`Gordon F. Clyde
`Thomas A. Gilbertson
`Allen J. Hanley
`Peter J. Hoey
`
`Daniel Int-Hout
`Merle F. McBride
`William E. Murphy
`Bjarne Olesen
`Elizabeth A. Parke
`William V. Richards
`Gaylon Richardson
`Ganesan Sundaresan
`Michael W. Woodford
`George S. Yamamoto
`Grenville K. Yuill
`Donald G. Colliver, ExO
`James E. Wolf, CO
`
`Jim L. Heldenbrand, Manager of Standards
`SPECIAL NOTE
`
`This Guideline was developed under the auspices of the American Society of Heating, Refrigerating and Air-Conditioning Engineers
`(ASHRAE). ASHRAE Guidelines are developed under a review process, identifying a guideline for the design, testing, application, or evalua-
`tion of a specific product, concept, or practice. As a guideline it is not definitive but encompasses areas where there may be a variety of
`approaches, none of which must be precisely correct. ASHRAE Guidelines are written to assist professionals in the area of concern and exper-
`tise of ASHRAE’s Technical Committees and Task Groups.
`ASHRAE Guidelines are prepared by project committees appointed specifically for the purpose of writing Guidelines. The project
`committee chair and vice-chair must be members of ASHRAE; while other members of the project committee may or may not be ASHRAE
`members, all must be technically qualified in the subject area of the Guideline.
`Development of ASHRAE Guidelines follows procedures similar to those for ASHRAE Standards except that (a) committee balance
`is desired but not required, (b) an effort is made to achieve consensus but consensus is not required, (c) guidelines are not appealable, and (d)
`guidelines are not submitted to ANSI for approval.
`The Manager of Standards of ASHRAE should be contacted for:
`a. interpretation of the contents of this Guideline,
`b. participation in the next review of the Guideline,
`c. offering constructive criticism for improving the Guideline,
`d. permission to reprint portions of the Guideline.
`
`ASHRAE INDUSTRIAL ADVERTISING POLICY ON STANDARDS
`
`ASHRAE Standards and Guidelines are established to assist industry and the public by offering a uniform method of testing for rating
`purposes, by suggesting safe practices in designing and installing equipment, by providing proper definitions of this equipment, and by
`providing other information that may serve to guide the industry. The creation of ASHRAE Standards and Guidelines is determined by the
`need for them, and conformance to them is completely voluntary.
`In referring to this Standard or Guideline and in marking of equipment and in advertising, no claim shall be made, either stated or
`implied, that the product has been approved by ASHRAE.
`
`ASHRAE uses its best efforts to promulgate Standards and Guidelines for the benefit of the public in light of available information and
`accepted industry practices. However, ASHRAE does not guarantee, certify, or assure the safety or performance of any products,
`components, or systems tested, installed, or operated in accordance wi h ASHRAE’s Standards or Guidelines or that any tests conducted
`under its Standards or Guidelines will be nonhazardous or free from risk.
`
`DISCLAIMER
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`Page 2 of 20
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`

`
`TABLE OF CONTENTS
`ASHRAE Guideline 3-1996, Reducing Emission of Halogenated
`Refrigerants in Refrigeration and Air-Conditioning Equipment and Systems
`
`Page
`Section
`Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
`
`1. Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
`
`2. Scope. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
`
`3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
`
`4. Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
`4.1 General Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
`4.2 Appliance Specific Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
`4.3 Unitary System Specific Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
`4.4 Large Equipment Specific Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
`
`5. Product Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
`5.1 Refrigerant Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
`5.2 System Cleanliness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
`5.3 Vibration Tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
`
`6. Manufacture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
`6.1 Evacuation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
`6.2 Holding Charges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
`6.3 Cleanliness of Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
`6.4 Factory Leak Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
`6.5 Operating Test Gas Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
`
`7.
`
`Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
`7.1 Installation of Field-Erected Equipment and Systems. . . . . . . . . . . . . . . . . . . . . . 7
`7.2 Pressure Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
`7.3 Leak Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
`7.4 Evacuation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
`7.5 Charging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
`
`8. Service/Operation/Maintenance/Decommissioning . . . . . . . . . . . . . . . . . . . . . . . . . . .8
`8.1 General Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
`8.2 Appliance Specific Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
`8.3 Large Equipment Specific Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
`
`9. Refrigerant Recovery, Reuse, and Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
`9.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
`9.2 Refrigerant Disposition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
`9.3 Refrigerant Transfer, Transport, and Storage . . . . . . . . . . . . . . . . . . . . . . . . . . .12
`9.4 Disposal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
`9.5 Appliance Specific Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
`
`10. Training of Personnel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
`
`11. Handling and Storage of Refrigerants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
`11.1 System Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
`11.2 Recovery Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
`11.3 Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
`11.4 Charging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
`
`12. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
`
`Annex A, Training of Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
`
`Annex B, Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
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`Page 3 of 20
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`

`
`(This foreword is not part of this guideline but is provided
`for information only.)
`
`FOREWORD
`
`When the potential for depletion of stratospheric ozone
`as a result of atmospheric release of chlorofluorocarbons
`(CFCs) was first discussed, ASHRAE appointed a task group
`to study the issue and to develop appropriate policy and pro-
`gram recommendations to the Board of Directors.
`In response, a comprehensive action program was initi-
`ated. It included research, education, communication, and
`training directed toward the various aspects of the CFC issue.
`A part of this program was the development of a guideline for
`reducing CFC refrigerant emission. This was published as
`ASHRAE Guideline 3-1990.
`Since that date, it has been determined that all chlorine-
`containing refrigerants, HCFCs as well as CFCs, are detri-
`mental to the ozone layer and their emission should be mini-
`mized.10 Guideline 3 has been revised to reflect this more
`stringent policy.
`This guideline recommends practices and procedures
`that will reduce emission into the atmosphere of halogenated
`refrigerants used in refrigeration and air-conditioning. As a
`guideline, this does not constitute a technical design docu-
`ment. It should be used in conjunction with other standards
`and codes or practice already in existence.
`Reducing emission of all halogenated refrigerants,
`including CFCs, HCFCs, and HFCs, may have a positive
`effect with respect to other environmental concerns such as
`global warming. In addition to environmental benefits, sav-
`ings from reduced refrigerant losses can be expected by
`applying this guideline to equipment and systems that use
`other refrigerants.
`
`Organization
`
`In Clauses 4, 8, and 9 of this guideline, measures that are
`generally applicable to all types of equipment are presented
`first. Then some measures are presented that are applicable to
`specific types of equipment. The text distinguishes between
`three types of equipment: appliances (household refrigera-
`tors, room air conditioners, etc.), unitary equipment, and
`large equipment. Provisions for one specific type of equip-
`ment may not apply to other types.
`
`Acknowledgments
`
`In the preparation of this guideline, use has been made of
`the recommendations contained in the “Code of Good Prac-
`tice” issued by the Commission of the European Communi-
`ties, Report EUR 9509 EN. Additionally, recommendations
`described by other organizations and appropriate provisions
`of various standards have been important sources of informa-
`tion presented in this guideline.
`
`1. PURPOSE
`
`This guideline recommends practices and procedures
`that will reduce inadvertent release of halogenated refriger-
`ants.
`
`2. SCOPE
`
`The practices and procedures in this guideline cover
`emission reduction of halogenated hydrocarbon and haloge-
`nated ether refrigerants:
`(a)
`from stationary refrigeration, air-conditioning, and
`heat pump equipment and systems;
`during manufacture, installation, testing, operation,
`maintenance, and disposal of equipment and systems.
`
`(b)
`
`3. TERMINOLOGY
`
`Although the following terms may have broader interpre-
`tations elsewhere in the industry, their specific meanings as
`used in this guideline are as follows.
`
`CFC: a fully halogenated (no hydrogen remaining) halocar-
`bon containing chlorine, fluorine, and carbon atoms.
`HCFC: a halocarbon that contains fluorine, chlorine, carbon,
`and hydrogen.
`HFC: a halocarbon that contains only fluorine, carbon, and
`hydrogen.
`joint, brazed: a gas-tight joint obtained by joining metal parts
`with alloys that melt at temperatures higher than 800°F
`(426°C) but less than the melting temperatures of the joined
`parts.
`joint, mechanical: a gas-tight joint obtained by the joining of
`metal parts through a positive holding mechanical construc-
`tion (such as a flanged joint, screwed joint, or flared joint).
`joint, soldered: a gas-tight joint obtained by joining metal
`parts with metallic mixtures or alloys that melt at temperatures
`above 400°F (204°C) but not exceeding 800°F (426°C).
`joint, welded: a gas-tight joint obtained by the joining of metal
`parts in the plastic or molten state.
`pressure, design: the maximum allowable working pressure
`for which a specific part of a system is designed.
`pressure, maximum working: (see pressure, design).
`pressure, operating: the pressure occurring at a reference
`point in a refrigerating system when the system is in operation.
`pressure-relief device: a valve or rupture member designed to
`relieve excessive pressure automatically.
`prevention-of-vacuum system: a refrigerant pressure control
`that prevents refrigerant loss and infiltration into idle low-
`pressure chillers; it is also used to pressurize for leak testing
`without the use of noncondensables.
`purging: removal of noncondensable gases from the system.
`purging device: an automatic, semi-automatic, or hand-oper-
`ated device that collects noncondensable gas from the con-
`denser or receiver.
`receiver: a vessel in the refrigerating system designed to
`ensure the availability of adequate liquid refrigerant for proper
`functioning of the system and to store the liquid refrigerant
`when the system is pumped down.
`reclaim: to process used refrigerant to new product specifica-
`tions.
`recover: to remove refrigerant in any condition from a system
`and store it in an external container.
`recycle: to reduce contaminants in used refrigerants by sepa-
`rating oil, removing noncondensables, and using devices such
`as filter dryers to reduce moisture, acidity, and particles.
`
`ASHRAE Guideline 3-1996
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`rupture disc: a safety device that will rupture at a predeter-
`mined pressure.
`small, hermetically sealed system: a factory-charged refriger-
`ating system using less than 2.3 kg (5 lb) of refrigerant that is
`welded, brazed, soldered, or otherwise joined together in such
`a manner as to create a sealed system typically capable of
`operating for 25 years without maintenance or repair.
`vacuum, deep (high vacuum): a vacuum of 130 Pa (1000
`microns) or less of absolute pressure.
`valve, pressure-relief: a pressure-actuated valve held closed
`by a spring or other means and designed to automatically
`relieve pressure in excess of its setting.
`valve, purge: a device to allow noncondensable gases to flow
`out of the system.
`
`4. DESIGN
`
`This clause deals with the design of air-conditioning and
`refrigerating systems and components and identifies possible
`sources of loss of refrigerants to the atmosphere. The under-
`standing and application of established techniques in both the
`design and construction of refrigerating systems provide a
`good foundation for the prevention of refrigerant release to
`the atmosphere.
`Instructions that will instruct field personnel to install,
`operate, and service the equipment to minimize refrigerant
`emission shall be provided.
`
`4.1 General Topics
`4.1.1 Compressors. Leaks associated with compressors
`may be related to the design of the compressor or to the asso-
`ciated equipment fitted to it, e.g., gauge and cut-out connec-
`tions, relief valves, and connected piping.
`4.1.1.1 Shaft Seals. Shaft seals are required on open-
`style compressors and can be a source of refrigerant leakage.
`Seals should be designed recognizing that in operation the
`refrigerant and oil to which they will be exposed may contain
`contaminants.
`Shaft-seal designs that do not rely on the commonly used
`carbon faces are available. Double-faced seals and single-car-
`bon seals with improved features to keep the carbon in a wet
`state have been found to be effective and are recommended.
`The design and installation of the shaft-seal assembly
`should minimize external oil loss and prevent direct refriger-
`ant loss. Lack of lubrication during shutdown periods can
`cause mating faces of the seal to dry out and adhere together.
`On large systems, a separate oil pump to lubricate the seal
`prior to starting the compressor is recommended.
`Open compressors typically have carbon-face seals that
`require positive pressure in order to function properly. Since
`these are not two-way seals, leakage may occur during evac-
`uation. To prevent leakage, temporary sealing measures such
`as shaft caps or clay-like weather stripping around the protru-
`sion of the shaft should be used.
`The motor-compressor alignment is critical in limiting
`refrigerant leakage and is affected by the style of the coupling
`and the speed and power of the motor. Refrigeration machin-
`ery requires stringent alignment to accommodate thermal
`growth over the load and temperature ranges.
`
`Shutdown and start-up procedures should ensure that oil
`is present to wet the seal faces. It may be necessary to run the
`oil pump and rotate the shaft periodically during long shut-
`down periods. If this is not possible, the seals should be
`inspected and lubricated before starting the system.
`4.1.1.2 Vibration. Vibration
`from gas-pressure
`pulses and moving parts can cause leaks. Some improvement
`can be achieved by placing the compressor on an adequate
`solid foundation and providing resilient mountings.
`For those compressors that are spring mounted, vibration
`elimination should be provided in the suction and discharge
`lines. When piping vibration eliminators are used, they should
`be parallel with the shaft of the compressor and anchored
`firmly at the upstream end in the suction line and at the down-
`stream end in the discharge line.
`Vibrations from gas pulses are best handled by a good
`muffler placed as close as possible to the compressor.
`Adequate support of piping connections to the compres-
`sor is important to avoid stresses that could lead to leakage.
`(See also 4.1.3.4.)
`4.1.1.3
`Isolation. Adequate isolation of system com-
`ponents, such as gauges, operating controls, and compressors,
`should be provided to minimize refrigerant loss during servic-
`ing or replacement in accordance with ASHRAE Standard
`15.1
`
`Compressor isolation valves should be provided on both
`the suction and discharge sides of the compressor to minimize
`release of refrigerant during service work. Isolation capability
`should be provided for any other compressor connections. If
`the connection size is greater than 150 mm (6 in.), the provi-
`sion of isolation valves is not necessary but pump-out capa-
`bility should be provided or readily available for system
`servicing. (See also 4.1.4.)
`4.1.2 Condensers and Evaporators. Properly designed
`and manufactured condensers and evaporators normally have
`few leakage problems. However, the following points require
`consideration and appropriate action.
`(a) Refrigerant circuits should not leak.
`(b) Connections, such as refrigerant gauges and liquid
`level gauge glasses, are a potential source of leakage.
`Isolation valves are recommended to minimize leak-
`age in accordance with ASHRAE Standard 15.1
`4.1.2.1 Air-Cooled Condensers and Evaporators
`4.1.2.1.1 Excessive vibration from compressors or
`other equipment can cause tube failure. This effect may be
`eliminated by the use of anti-vibration mountings and vibra-
`tion eliminators. (See also 4.1.1.2.)
`4.1.2.1.2 Equipment should be designed to with-
`stand anticipated stress, vibration, and galvanic corrosion.
`Tubing supports should be constructed to minimize vibration
`and to provide protection against abrasion due to movement
`(see also 4.1.3.4) and must allow for thermal expansion.
`4.1.2.1.3 Construction materials and methods of
`design should be selected to preclude emissions of refrigerant
`as a result of leakage during normal operation.
`
`2
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`ASHRAE Guideline 3-1996
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`4.1.2.1.4 Condensers and evaporators should be
`designed to keep the refrigerant volume (charge) as small as
`possible.
`4.1.2.1.5 Air-cooled condensers and evaporators
`should be constructed with the fewest practicable number of
`joints and return bends. Brazing is the preferred method of
`joining (see also 4.1.3.2).
`4.1.2.2 Water-Cooled Condensers and Evaporators
`4.1.2.2.1 Excessive vibration can cause failure of
`shell-and-tube heat exchangers. Vibration from any of several
`sources can cause tube failure:
`(a) The boiling action in flooded evaporators can cause
`vibration at the natural frequency of the tubes, creat-
`ing excessive wear at tube supports and possible fail-
`ure. This problem can be avoided with properly
`spaced and sized tube supports.
`(b) Excessive fluid velocity in condensers and evapora-
`tors can set up vibrations that will cause premature
`tube failure. Precautions similar to those described in
`4.1.2.2.1(a) can minimize the problem.
`4.1.2.2.2 Excessive fluid velocity in water-cooled
`condensers and evaporators can lead to premature failure by
`erosion. As velocities increase, the potential for premature
`failure increases as the square of the velocity. Care must be
`taken that design velocities are within good practice for the
`material selected. Pluggage, especially in condensers, can
`result in increased velocities above design for normal flow
`through the heat exchanger. The potential for damage will be
`reduced by limiting velocities.
`4.1.2.2.3 The characteristics of fluids used in liquid
`chillers and liquid-cooled condensers vary widely and can
`lead to premature failure of tubes. Selection of tube materials
`and the tube wall thickness must be suitable for the fluids to
`be used in the system. In applications where fouled condenser
`water can lead to premature tube failure, the use of smooth-
`bore tubes is recommended. Proper filtration can reduce ero-
`sion caused by foreign particles in the fluid. Proper chemical
`treatment can minimize the effects of corrosive elements in
`the fluid.
`4.1.2.2.4 Reduced or suspended water flow can also
`lead to serious corrosion problems. Seawater-cooled systems
`are especially susceptible to corrosion, as are some systems
`using water containing traces of ammonia or microbiological
`organisms. These contaminants will attack the tubes and may
`also attack tube sheets and heat exchanger heads, leading to
`leakage. Facilities for routine flushing and inspection are
`advisable. Special linings and special tube materials may be
`required to minimize attack on these surfaces.
`4.1.2.2.5 Any of several conditions can lead to
`freeze-up that can cause severe damage and rupture of tubes.
`To prevent freeze-up, interlocked safety controls for pressure,
`temperature, and flow should be provided.
`4.1.3 Piping, Tubing, and Connections
`4.1.3.1 Pipe and fittings should be in accordance with
`requirements of ASME B31.52 or SAE J513.3 All design and
`installation of systems should be done in such a manner as to
`
`reduce the number of fittings and connections as much as
`practicable.
`Tapered pipe threads are not recommended for fittings in
`refrigerant circuits. Particularly in sizes of 25 mm (1 in.) or
`larger, they should be avoided. SAE 45-degree flare fittings
`and short radius elbows are not extremely reliable. Their use
`is discouraged.
`4.1.3.2 Because of increased resistance to pressure,
`temperature, and vibration stresses, flanged joints, welding,
`and brazing are the preferred methods of joining pipe to fit-
`tings, valves, and other components. Soft solder is not a rec-
`ommended alternative to brazing.
`4.1.3.3 All flanged joints should be in accordance
`with the requirements of ASME B31.5.2 Special care should
`be taken to ensure that gasketing materials are compatible
`with both the refrigerant and refrigerant oils.
`4.1.3.4 All pipe supports should be designed and
`installed to minimize vibration. All pipe supports should meet
`the requirements of ASME B31.52 regarding calculations of
`strength, movement, load, and standard components. Sup-
`ports should be designed to guard against electrolytic corro-
`sion and also to provide for protection of tubing components
`against external abrasion due to movement.
`4.1.3.5 Strainers, filters, and dryers should be utilized
`to control moisture and minimize damage to moving parts and
`avoid plugging of refrigerant circuits caused by contaminants
`in the system.
`4.1.3.6 Strainers, filters, and dryers should be isolated
`with valves to permit proper servicing of equipment.
`4.1.3.7 Corrosion protection should be used to pre-
`vent rusting of exposed steel components, particularly in the
`low-temperature section of systems.
`4.1.3.8
`In refrigerant piping design, any line that can
`be filled with refrigerant liquid should not have two stop
`valves, or a stop valve and solenoid valve in series, unless pro-
`vided with a relief. If liquid is trapped between two valves, it
`can experience thermal expansion and rupture the connecting
`tubing.
`4.1.4
`Isolation Valves
`4.1.4.1
`Isolation valves should have retained or cap-
`tive spindles and facilities for tightening or replacement of the
`gland packing under line pressure. All manual valves should
`be provided with gasketed seal caps made of nonferrous metal
`to fit over the stem and be threaded to the valve body. Seal
`caps should be attached to the valve body by a strap or chain
`to avoid losing them in service.
`4.1.4.2 For pipe sizes in excess of 20 mm (3/4 in.)
`nominal diameter, flanged, welded, or brazed ends should be
`utilized for all valves. Threaded valves are acceptable if the
`threads are backwelded.
`4.1.5 Access Valves for Charging, Evacuation, or Both
`4.1.5.1 Access valves should be provided for evacua-
`tion and liquid charging of refrigeration systems. Valves
`should be provided in systems for liquid drainage and vapor
`extraction. At a minimum, every refrigerant circuit should be
`provided with a vapor access valve and a liquid access valve.
`
`ASHRAE Guideline 3-1996
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`(b)
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`4.1.5.2
` Access valves should be located where pres-
`sure readings should be taken. They should be provided with
`caps as in 4.1.4.1 and should be used for vapor and liquid
`charging to minimize potential leak sources.
`4.1.6 Relief Devices. The intent of this subclause is to
`recommend the use of relief devices that minimize refrigerant
`loss to the atmosphere. Relief devices for refrigerating sys-
`tems are prescribed in ASHRAE Standard 15.1
`4.1.6.1 Normal practice is to provide separate relief
`devices for the high and low sides; however, high-side pres-
`sure-relief devices may be piped so as to discharge into the
`low side of the system provided
`(a)
`they are of a type not appreciably affected by back
`pressure, and
`the low side is equipped with a pressure-relief device
`of sufficient capacity as specified in ASHRAE Stan-
`dard 151 to protect all connected vessels, compres-
`sors, and pumps subjected
`to excess pressure
`simultaneously.
`In centrifugal machines where the condenser cannot be
`isolated from the evaporator, a single pressure-relief device
`will suffice to protect the system in accordance with
`ASHRAE Standard 15.1
`4.1.6.2 Where a relief valve is used, a rupture disc
`should be installed upstream of the valve to protect the valve
`from corrosion or inadvertent leakage. An indicator should be
`installed between the rupture disc and the relief valve to indi-
`cate that the disc has ruptured. The rupture disc should be a
`nonshattering type. Once the rupture disc has burst, it should
`be replaced as soon as possible. It may be necessary to remove
`the remaining refrigerant charge before replacing the disc.
`Note: When pressure-relief devices are installed in
`series, provisions of Section 8 of the ASME Unfired
`Pressure Vessel Code4 should be observed.
`
`4.2 Appliance Specific Topics
`4.2.1
`It must be recognized that any piercing of the
`refrigerating system presents a potential refrigerant leak
`source. Therefore, any provision herein relating to accesso-
`ries, devices, or connections is not intended to suggest that
`such accessories, devices, or connections should be included
`in a specific product or system.
`4.2.2 Valves in a refrigerating system are also potential
`leak sources. Consequently, except as 4.1.5 provides for a sin-
`gle access point or equally effective design feature, valves
`should generally not be included in factory-charged, hermet-
`ically sealed systems.
`4.2.3 Factory-charged, hermetically sealed systems that
`are listed by a nationally recognized testing agency should be
`considered to comply with provisions of 4.1.3.1 and 4.1.3.3.
`4.2.4 For factory-sealed systems, soldering, epoxy join-
`ing, or any other method demonstrated to maintain the her-
`metic nature of the system is acceptable as an alternative to
`brazing.
`4.2.5 Access valves for charging, evacuation, or both
`should be installed except as otherwise provided therein (i.e.,
`equally effective design feature).
`
`4.2.6 On factory-charged, hermetically sealed systems
`with a refrigerant charge of less than 2.3 kg (5 lb), a servicing
`aperture or equally effective design feature (e.g., process tube
`or stub) that will facilitate the recovery of refrigerant during
`service and repair or disposal is acceptable
`4.2.7 Factory-charged, hermetically sealed systems that
`are listed by a nationally recognized testing laboratory should
`be considered to comply with the provisions of 4.1.6.
`
`4.3 Unitary System Specific Topics
`Unitary air conditioners and heat pumps are manufac-
`tured, sold, and installed with little or no provision for preven-
`tive maintenance on
`the sealed refrigerating system.
`Accordingly, the only service involvement in the refrigerating
`system is when the home or building owner notices the sys-
`tem’s inability to provide comfort. Quite often, refrigerant
`leaks are the reason for the system’s loss of performance. It is,
`therefore, recommended that unitary systems be designed to
`facilitate their manufacture, transport, and installation with
`minimum probability for leaks during 15- or 20-year life
`cycles. It is industry practice that unitary systems meet the
`requirements and bear the seal(s) of approval of one or more
`nationally recognized testing agencies.
`4.3.1 Compressors. Most unitary system compressors
`are hermetic. Process tubes extending from the compressor
`should be pinched and soldered or brazed as approved by a
`nationally recognized testing agency. Suction and discharge