1、_SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising theref
2、rom, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions.Copyright 2013 SAE InternationalAll rights reserved. No part of this publi
3、cation may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE.TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada)Tel: +1 724-776-4970 (out
4、side USA)Fax: 724-776-0790Email: CustomerServicesae.orgSAE WEB ADDRESS: http:/www.sae.orgSAE values your input. To provide feedbackon this Technical Report, please visithttp:/www.sae.org/technical/standards/J1628_201407SURFACE VEHICLERECOMMENDED PRACTICEJ1628 JUL2014Issued 1998-11Revised 2014-07Supe
5、rseding J1628 AUG2011Technician Procedures for Refrigerant Leak Detection in Serviceof Mobile Air Conditioning SystemsRATIONALEWith the publication of SAE J2970 “Minimum Performance Requirements for Non-Refrigerant Tracer Gasses and Electronic Tracer Gas Leak Detectors,” this standard is updated to
6、incorporate the use of Non-Refrigerant Tracer Gasses and Electronic Tracer Gas Leak Detectors that meet J2970. Comments from the previous ballot have been addressed.FOREWORDThe purpose of this SAE Standard is to establish guidelines for leak detection procedures when servicing motor vehicle air-cond
7、itioning refrigerant systems. There are many approaches for determining the existence and location of a refrigerant system leak. However, many of these approaches will not provide reliable leak detection. When servicing MACsystems, it is important that they be repaired to maintain their design inten
8、t concerning refrigerant containment rates, for system performance, refrigerant system safety, and to protect the environment. Single evaporator MAC systems can have a design intent refrigerant charge quantity of less than 20 oz (567 g) and a refrigerant leakage rate of considerably less than 20 g p
9、er year. Identifying and repairing small system leaks is important, for system performance and reliability. In addition, some hybrid vehicles, or electric vehicles have larger refrigerant capacities than would normally be expected for vehicle size, because the vehicles incorporate an A/C refrigerant
10、 circuit for cooling high-voltage battery and/or control electronics under certain operating conditions. For these vehicles, refrigerant leak detection locations can also include other vehicle components other than the air conditioning system. 1. SCOPEThis SAE Recommended Practice applies to the use
11、 of generally available leak detection methods to service motor vehicle passenger compartment air conditioning systems.2. REFERENCES2.1 Related PublicationsThe following publications are provided for information purposes only and are not a required part of this SAE Technical Report.SAE INTERNATIONAL
12、 J1628 Revised JUL2014 Page 2 of 122.1.1 SAE PublicationsAvailable from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or 724-776-4970 (outside USA), www.sae.org.SAE J639 Safety Standards for Motor Vehicle Refrigerant Vapor Compression
13、 SystemsSAE J1627 Performance Criteria for Electronic Refrigerant Leak DetectorsSAE J2297 Ultraviolet Leak Detection: Stability and Compatibility Criteria of Fluorescent Refrigerant Leak Detection Dyes for Mobile R-134a and R-1234yf (HFO-1234yf) Air-Conditioning SystemsSAE J2791 HFC-134a Refrigerant
14、 Electronic Leak Detectors, Minimum Performance CriteriaSAE J2913 R-1234yf HFO-1234yf Refrigerant Electronic Leak Detectors, Minimum Performance CriteriaSAE J2970 Minimum Performance Requirements for Non-Refrigerant Tracer Gasses and Electronic Tracer Gas Leak Detectors3. REFRIGERANT LEAK DETECTION
15、METHODS COVERED IN THIS DOCUMENTx Visible oil leakage on system parts, often highlighted by road film, particularly at system joints.x Water/soap solution bubbles.x Using electronic leak detection devices, particularly those certified to SAE standards. x Trace dye that meets SAE J2297 requirements.x
16、 System vacuum and pressure decay pressure change/loss over time. Except where vacuum and/or pressure decay is used on an isolated component, they are intended to confirm the existence of a leak in the overall system. The complete system test will not pinpoint the location of the leak. One of the me
17、thods described above will be needed to pinpoint the location of the leak. Refer to No. 8, System Vacuum and Pressure Decay Procedures (pressure/vacuum change over time).x Using Non-Refrigerant Tracer Gasses and Electronic Tracer Gas Leak Detectors that meet J29703.1 Using the Appropriate Leak Detec
18、tion ProcedureIt is important to understand that some of the methods have limited ability to identify a leak, and the use of some methods i.e., pressurizing the system with nitrogen gas or with a high pressure refrigerant could cause damage to the refrigerantsystem. The industry has developed servic
19、e procedures and equipment that provide the most appropriate way to determine system refrigerant leakage and to minimize the use of additional refrigerant. In many cases, the technician will find it appropriate to use a combination of procedures to pinpoint a leak.3.1.1 If the indicated leak is larg
20、e, the technician should begin by confirming its existence by reviewing the vehicle A/C service history and visual inspection. A large leak is defined as one that results in a significant loss of the refrigerant charge within a single A/C cooling season, such as evidenced by failure to pass the vehi
21、cle manufacturers cooling performance test. Very low or no pressure in the system when the vehicle is received might be an indication of a very large leak.3.2 Three levels of leak detection. Level 1 is for large leaks, and even if effective in pinpointing a large leak, should be followed by a subseq
22、uent level (Level 2 or Level 3) to ensure that all repairable leaks have been found.SAE INTERNATIONAL J1628 Revised JUL2014 Page 3 of 123.3 The most effective and reliable refrigerant leak detection methods include the following steps, starting with methods that will locate major refrigerant leaks,
23、to methods that will locate leakage rates of a few grams per year. It should be noted that to minimize MAC system refrigerant emissions and assure consumer satisfaction, identifying all potential system refrigerant leakage can only be accomplished by using the correct procedures and in conjunction w
24、ith electronic and trace dye diagnostics. 4. INITIAL MAC SYSTEM INSPECTION LEVEL I PROCEDURE4.1 Visual inspection for major leakage install a gauge set and check static pressure in the system.4.2 Visible oil leakage on system parts should be the first step in any leak test procedure. If vehicle has
25、low or no pressure in the system when it arrives for service, it is important to take time to carefully perform this step.4.2.1 Leakage may be indicated by oily dirt, particularly at refrigerant system joints. If the leakage is almost entirely from a single location, a refrigerant system having a la
26、rge leak may have some indication of oil collection on the surface of the refrigerant part, and with exposure time, the area will collect dirt. Visually inspect the system, looking for oily dirt at refrigerant line joints and where lines and components may make physical contact, and rub through to p
27、roduce a leak. Check the hood liner or surface to check for excessive oil accumulation due to a compressor shaft seal leak from a high-mount compressor. Note: a small amount of oil is not necessarily an indication of a shaft seal leak. If accessible, check the condensate drain of the evaporator for
28、signs of oil which may indicate an evaporator leak. 4.2.2 Leakage indicated by trace dye already in the system. Many vehicle makers install trace dye in the A/C system during manufacturing. If so, trace dye is likely to produce visible evidence. See Section 5 for use of trace dye.4.3 Use of Water or
29、 Soap Water Solution If there is no or very low pressure in the system, skip this step. Bubbles from water and soap solution applied to refrigeration system parts/joints are only effective in locating and pinpointing large refrigerant leaks, and therefore wouldrequire some recharging of the system f
30、irst. Be sure to check for indication of dye before using water or soap water solution to avoid washing away the dye.4.3.1 The limitations of using a liquid bubble leak detection method are indicated in the chart, Figure 1, which indicates that one bubble per second would be caused by leaks per year
31、 equal to double or triple the system capacity. Figure 2 compares the soap solution bubble method with leak detection using SAE J1627 and SAE J2791/J2913 electronic leak detectors. FIGURE 10102030405060Soap WaterRefrigerantLossOunces/yearRefrigerant Leak Detection BubblesIdentifiable Leak Rate1 bubb
32、le per secondSAE INTERNATIONAL J1628 Revised JUL2014 Page 4 of 124.3.2 As seen in Figure 1, using water or water and soap and looking for bubbles will not identify small leaks, since one bubble per second indicates a refrigerant leak of over 45 oz (1276 g) per year exceeding over twice the total sys
33、tem refrigerant charge requirements for most cars. When attempting to determine if the system has a smaller leak, but still large enough to require service, refrigerant leak bubble identification is of little value, and use of SAE electronic leak detectors and/or trace dye is required. 4.3.3 Figure
34、2 compares water/soap detection for different SAE rated electronic leak detectors. One visible bubble per second indicates a refrigerant leak rate of approximately 45 oz/1276 g per year, as compared to using SAE J2791 or SAE J2913 electronic leak detectors certified to identify refrigerant leakage o
35、f 0.15 oz or 4 g/year.FIGURE 2 - REFRIGERANT LEAK DETECTION4.3.4 For smaller capacity system refrigerant leaks, refer to procedures in Level IV in Section 8.5. LEVEL II LEAK DETECTION PROCEDURES5.1 A full refrigerant charge is not required to detect leaks. In general, the system pressure in psig is
36、similar to the surrounding area temperature in degrees Fahrenheit of the system (work area temperature). If the work area temperature is in the range of 24 C (75 F) the system static pressure (no compressor operation) will indicate a gauge pressure reading in the range of 79 psig (543 kPa gauge) for
37、 HFC-134a, 82 psig (565 kPa gauge) for R-1234yf. The work area temperature must be warm enough (at least 15 C 59 F for electronic leak detection per 5.2, and should result in a gauge pressure of approximately 57 psig (393 kPa) for R-134a, 60 psig (414 kPa gauge) for R-1234yf. At high ambient, the pr
38、essure will be higher. Consult a refrigerant pressure-temperature chart and determine if the system pressure reading is correct for ambient in the work area, to ensure there is adequate refrigerant in the system.5.1.1 Step 1: Perform visual inspection as outlined in Level I as described in Section 4
39、.5.1.2 Step 2: Check pressure in system. If less than appropriate for the ambient temperature, slowly add small amounts of refrigerant until pressure rises above this level. Ambient temperatures should be above 15 C. Check for hissing noises as refrigerant is added as another check for gross leaks.
40、If noise is heard, stop adding charge, determine the source, and repair the leak before adding more refrigerant. Using the appropriate refrigerant type pressure-temperature chart can be used to determine the expected system pressure.0.15 0.5454 141276020040060080010001200Ounces/Yr Grams/YrOneBubble/
41、secSAE INTERNATIONAL J1628 Revised JUL2014 Page 5 of 125.2 Quick Leak Check Repair5.2.1 A charge amount of approximately 10 to 15% of the total charge will result in sufficient pressure to perform a leak check with an electronic detector. Adding additional refrigerant will not increase system pressu
42、re. If the system has been open and has air in it, adding refrigerant without evacuating will result in a slightly higher pressure. However, this will not result in an error in leak checking. Since the refrigerant shall be removed to complete service, the recovery/recycle equipment will process the
43、refrigerant and remove the air before the final full charge is added to the system. The information in Figure 3 shows the addition of refrigerant into an empty system and reaching a saturated equalized pressure condition with pure refrigerant after the system is evacuated and refrigerant added to a
44、system (with air) without evacuation. 5.2.1.1 For safety reasons, mixing refrigerant and air in the system, is not recommended. When using SAE J2843 R-1234yf equipment the automatic process will evacuate the system prior to refrigerant being charged into the system. 5.2.2 If the compressor is to be
45、operated, such as to circulate trace dye, a full refrigerant charge amount should be added. But this should not be done until all of the checks for gross leaks and the other processes in Level III -Section 6 - are completed.FIGURE 35.3 General Considerations5.3.1 Only the system refrigerant itself o
46、r a tracer gas that is part of a leak detection system certified to SAE J2970 has been included in SAE leak detection standards as a safe, effective pressurizing substance for electronic leak detection in automotive A/C systems.5.3.2 Using Other Means to Introduce Pressure into the MAC System5.3.2.1
47、 Without proper equipment and precautions, the use of other pressurizing substances can be costly, and the ability to identify small refrigerant leaks becomes difficult or impossible. It is not recommended that a technician use any other methods for field service to identify system refrigerant leaks
48、. The use of other substances may also result in safety concerns or system contamination if the substance is not properly removed,0204060801001205% 10% 15%Service FittingPressureHigh/lowsidePSIGPercent of System Refrigerant Charge System Refrigerant ChargeNo Vacuum Prior VacuumPure RefrigerantRefrig
49、erant & AirSaturated System Pressure with liquid/vapor at 85 degrees F. 29CSAE INTERNATIONAL J1628 Revised JUL2014 Page 6 of 125.4 Other Safety Concerns5.4.1 Pressurizing the entire closed circuit system over 1.1 MPa (160 psig) could cause failure of an evaporator. The use of shop compressed air can introduce moisture, contaminates (rust) or shop air compressor oil into the system, saturate the desic
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