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 there
2、from, 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 International All rights reserved. No part of this p
3、ublication 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: +1 724-776-497
4、0 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J2791_201301 AEROSPACE SURFACE VEHICLE STANDARD J2791 JAN2013 Issued 2007-01 Revi
5、sed 2013-01 Superseding J2791 SEP2008 HFC-134a Refrigerant Electronic Leak Detectors, Minimum Performance Criteria RATIONALE This document is being updated to add an appendix to describe the requirements for certification according to SAE J2911. FOREWORD The purpose of this SAE Standard is to establ
6、ish minimum performance criteria for a modern class of electronic probe-type leak detectors intended for use in automotive air conditioning systems with HFC-134a refrigerant. 1. SCOPE This SAE Standard provides testing and functional requirements to meet specified minimum performance criteria for el
7、ectronic probe-type leak detectors. So they will identify smaller refrigerant leaks when servicing all motor vehicle air conditioning systems, including those engineered with improved sealing and smaller refrigerant charges to address environmental concerns and increase system efficiency. This docum
8、ent does not address any safety issues concerning their design or use. 2. REFERENCES 2.1 Applicable Documents The following publication forms a part of this specification to the extent specified herein. Unless otherwise indicated, the latest issue of SAE publications shall apply. 2.1.1 SAE Publicati
9、on Available 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 J1739 Potential Failure Mode and Effects Analysis in Design (Design FMEA), Potential Failure Mode and Effects Analysis in
10、Manufacturing and Assembly Processes (Process FMEA) SAE J2911 Procedure for Certification that Requirements for Mobile Air Conditioning System Components, Service Equipment, and Service Technician Training Meet SAE J Standards. SAE J2791 Revised JAN2013 Page 2 of 13 3. GENERAL DESCRIPTION AND OPERAT
11、ING INSTRUCTIONS 3.1 The detector shall be suitable for use in an automotive service garage and operate in ambient temperatures of 15 to 49 C (59 to 120 F). 3.2 The detector shall have at least three scales that can be manually selected: (1) 4 g/yr (0.15 oz/yr); (2) 7 g/yr (0.25 oz/yr); (3) 14 g/yr
12、(0.5 oz/yr). It shall be tested to meet the performance specifications of this standard by a qualified independent laboratory. The laboratory shall maintain all documentation related to its testing, including calibration and maintenance data for its equipment, for a period of five years following th
13、e test of the specific detector. 3.3 If it passes, the detector shall carry a label that states “Design certified by (name of testing laboratory) to meet SAE J2791 with lettering in bold face type at least 3 mm high. 3.4 If it does not pass, the detector may be retested subject to the limits of Sect
14、ion 10. If a detector fails beyond these retest limits, it may be retested only after the marketer has documented changes made to correct the failure and given the data to the testing laboratory. A detector must pass the procedures in Sections 7 and 8. A failure in either or both of those sections r
15、equires a complete retest. The detector also must meet the requirements of Section 9, passing the no-false-triggering requirement for transmission oil and engine oil (Nos. 14 and 15) and clearing within 20 seconds after a permitted false-trigger. 4. WHAT MUST ACCOMPANY THE DETECTOR 4.1 The marketing
16、 company shall provide operating instructions for the detector that cover calibration, operating instructions and maintenance, including replacement of any sensors, filters or power supply. 4.2 Tools, adapters and needed adjustment and calibration devices (including calibration and/or reference bott
17、les) for the detector must be included with the detector. 4.3 The marketing company shall provide all needed safety information and labeling. 4.4 The marketing company shall provide the Section 9 list of all common under hood chemicals that may affect the operation of an electronic leak detector and
18、 indicate by Y, if its detector will false-trigger from exposure to each of the chemicals on the list, or N if it will not false-trigger. 4.5 The resistance to false triggering shall be based on the test procedures described in Section 9. False triggering is defined as the detector making the same o
19、r similar indication (sound and/or light) as if it detected a refrigerant leak. 5. REQUIRED BASIC FUNCTIONS 5.1 The detector may self-calibrate or require manual calibration, but once calibrated for an operation, it must hold that calibration for a time sufficient to perform the operations described
20、 in Sections 7 and 8 (including 8.1 to 8.6). This does not preclude automatic recalibration for a probe that has been inserted into a contaminated atmosphere (as per Section 8), readjustment of sensitivity by operator selection, or an audible-and-or-visual warning of a condition beyond the operating
21、 scope of its design. The latter must be obviously different from the indication of a refrigerant leak, although the same functional trigger may be used. Example: a steady indicator light vs. a flashing indicator light. 5.2 The detector must demonstrate automotive garage durability by continuing to
22、function normally after being dropped 1.2 m (4.0 ft) to a hard surface, such as a concrete floor, four times. This test may be performed with the detector in a protective caddy, provided the caddy is a standard part of the basic detector kit, and does not affect in-shop use of the detector, or testi
23、ng of the detector under all procedures in Sections 7, 8, 9 and 10. SAE J2791 Revised JAN2013 Page 3 of 13 5.3 The detector must demonstrate automotive garage durability by continuing to function normally after the probe tip has been submerged to a depth of six mm (0.25 in) in a pan of water and dra
24、wn through the water at a rate of 75 mm (3 in) per second for two seconds and then, after wiping clean and given any other cleaning/maintenance prescribed by the manufacturer in its operating instructions manual, including but not limited to a sensor replacement or filter change. 6. LEAK DETECTION T
25、EST EQUIPMENT 6.1 The testing shall be performed with the probe in a 610 mm (2 ft) cube clear sealed chamber as described in the appendix. Figures A1 and A2. 6.1.1 Illustrations and details of the chamber are described in the Appendix. A vertical wall of the chamber shall have a slot 200 mm (8 in) w
26、ide or wider, and large enough for a probe from an externally mounted detector to go through. The slot opening shall be sealed with overlapping strips of a rubber material that conforms sufficiently around the probe to maintain the specified level of contaminated atmosphere, or a butt-joint of confo
27、rming rubber seals with additional sealing from face seals on the detector probe neck that are in contact with the butt joint. The rubber strips and face seals may be lubricated to provide smooth movement of the probe and any surrounding brace as described in 6.3. 6.1.2 The chamber shall have an acc
28、ess door large enough to insert a calibrated leak standard, a cylindrical sleeve or round-hole access point for a gas-tight syringe, and a built-in mixing fan (120 V, approximately 40 cfm) to circulate an injection of refrigerant gas to produce uniform distribution of injected gas for a contaminated
29、 atmosphere test. The chamber should have a provision for attaching a vacuum source (such as a small household vacuum motor) to permit rapid clearing of the chamber following a contaminated atmosphere test. The cylindrical sleeve or round-hole access shall include a sealing plug or other provision f
30、or sealing following use of the gas-tight syringe. 6.1.3 The four calibrated leak standards used for the tests shall be calibrated per methods and instruments per the National Institute of Standards and Technology, Washington, DC 20234, and the standards shall be rated accurate to within 20%. The le
31、ak rates shall be in common units 14 g/yr (0.5 oz/yr), 7 g/yr (0.25 oz/yr), 4 g/yr (0.15 oz/yr) and 2.0 g/yr (0.0625 oz/yr). The leak standards shall contain 100% HFC-134a. The standards or their mounting locations in the chamber shall ensure the base of the standard is 75 mm (3 in) or more from the
32、 floor of the chamber. This is to provide a sufficient drop for refrigerant coming from the leak standard orifice, to minimize refrigerant puddling around the orifice and/or orifice shroud if used. To mitigate testing inconsistency from possible air turbulence caused by the moving probe, the leak st
33、andards may be equipped (as a certification test option) with a shroud around the orifice port. The shroud protrusion from the orifice port shall be no more than 6 mm +0/-0.2 mm (0.236 in +0/-.01 in). A view of a sample configuration, with dimensions within those ranges is shown in the Appendix, as
34、Figure A3. If a shroud is used with any leak standard, this shroud also must be used with all other leak standards for certification of a detector. 6.1.4 The detector shall be mounted on a table with a moving platform, designed to produce a horizontal reciprocating motion of at least 150 mm (6 in),
35、and a motor drive adjusted to move the platform so the probe tip passes the specified calibrated leak at a rate of 75 mm (3 in) per second, from a distance of 9.5 mm (3/8 in) per 7.2 All moving probe tests in this standard shall be performed at that rate as the probe passes the orifice of the calibr
36、ated leak standard. The platform shall stop at each end of its travel for no less than eight, no more than 10 seconds. The stop may be manually controlled by a test operator or performed automatically with a switch at each end-of-travel and a timer. SAE J2791 Revised JAN2013 Page 4 of 13 6.2 It is n
37、ecessary to hold steady the detectors flexible neck and probe, as the detector probe moves side to side through the sealed slot in the vertical wall of the chamber. If the design of the flex neck requires, this may be done by adding to the platform a brace (may be C or U channel) sized to hold the f
38、lex neck and probe securely, and long enough to protrude through the slot to within a distance conveniently short of the 9.5 mm (3/8 in) from the orifice of the calibrated leak. 7. DETECTOR REQUIRED PERFORMANCE AND TEST PROCEDURE 7.1 Begin all testing for a single detector with a chamber cleared of
39、refrigerant from any previous testing. Give the calibrated leak standard any maintenance/cleaning prescribed by the manufacturer. Perform the leakage rate tests separately, with the specific calibrated leak standard in the same position within the chamber. Position the calibrated leak standard so it
40、s orifice is at the exact midpoint of the moving platforms travel. 7.2 Adjust the detector and probe position for all tests so detector and probe are at one extreme end of the test table sweep. The probe must sense three leakage rates: of 4 g/yr (0.15 oz/yr), 7 g/yr (0.25 oz/yr) and 14 g/yr (0.5 oz/
41、yr) when moved at a rate of 75 mm/sec (3 in/sec) past a calibrated leak standard, coming no closer than 9.5 mm (3/8 in) from the orifice of the calibrated leak. The 9.5 mm (3/8 in) distance from the orifice of the calibrated leak standard shall be horizontal or up to 45 degrees downward offset. Unde
42、r these same operating conditions, the detector also shall not indicate a leak of 2.0 g/yr (0.0725 oz/yr) leak with the detector sensitivity selector in the 4 g/yr (0.15 oz/yr) position, a 4 g/yr (0.15 oz/yr) leak with the sensitivity selector in the 7 g/yr (0.25 oz/yr) position, and a 7 g/yr (0.25
43、oz/yr) leak with the sensitivity selector in the 14 g/yr (0.5 oz/yr) position. 7.2.1 Begin with the calibrated leak standard for 2.0 g/yr (0.0725 oz/yr) in position. Warm up the detector, select 4 g/yr (0.15 oz/yr) and operate the moving table so the probe sweeps past the calibrated leak standard a
44、total of 10 times (five side to side and back again movements at the specified rate and distance from the orifice). The probe shall indicate no leak nine of 10 times or the leak detector fails. 7.2.2 Replace the 2.0 g/yr (0.0725 oz/yr) calibrated leak standard with the 4 g/yr (0.15 oz/yr) calibrated
45、 leak standard. Operate the moving table so the probe sweeps past the calibrated leak standard orifice a total of 10 times (five side to side and back again movements). The probe must sense the leak within two seconds and clear within two seconds of passing the orifice, at least nine of the 10 times
46、. “Clear” is defined as a clearly audible reduction in sound and/or substantial decrease in indicator lighting from the indication of a leak. If after an apparent “Clear” the detector sounds in the stop period at each end of travel, following any one of the 10 sweeps past the calibrated leak standar
47、d, the leak detector fails. 7.2.3 Immediately following the 4 g/yr (0.15 oz/yr) test, move the detector sensitivity selector to the 7 g/yr (0.25 oz/yr) position and perform a 10-sweep test with the 4 g/yr-calibrated leak standard still in position. The detector shall indicate no leak at least nine o
48、f 10 times or it fails. 7.3 Replace the 4 g/yr (0.15 oz/yr) calibrated leak standard with the 7 g/yr (0.25 oz/yr) calibrated leak standard and leave the detector sensitivity selector in the 7 g/yr (0.25 oz/yr) position. Perform a 10-sweep test and the detector shall indicate a leak within two second
49、s of passing the calibrated leak standard orifice, then clear within two seconds, at least nine of the 10 times, or it fails. 7.4 Immediately following the 7 g/yr (0.25 oz/yr) test, leave the 7 g/yr (0.25 oz/yr) calibrated leak standard in position and move the detector sensitivity selector to the 14 g/yr (0.5 oz/yr) position. Perform a 10-sweep test and the detector shall indicate no leak at least nine of the 10 times, or it fa
