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 reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2006 SAE International All rights reserved. No part of this publication m
3、ay 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: 724-776-4970 (outside USA)
4、 Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org ARP4835 AEROSPACE RECOMMENDED PRACTICE Issued 2006-09 Aerospace Fluid Power-Hydraulic Thermal Expansion Relief Valves RATIONALE This document was developed to assist the system designer in specifying the requirements
5、 for thermal relief valves that prevent the development of excessive pressure due to the thermal expansion of confined fluid. 1. SCOPE This SAE Aerospace Recommended Practice (ARP) establishes the general requirements for hydraulic thermal expansion relief valves used in aircraft and missile hydraul
6、ic systems having operating pressures and temperatures as identified in 1.2. 1.1 Purpose This document is intended for use in conjunction with a procurement specification to be prepared by the purchaser in which valve configuration, system fluid and other parameters for the particular application ar
7、e defined as required herein. 1.2 Classification The thermal relief valve shall be of classes and types based on the applicable system operating temperature and pressure. In addition, valves shall be classified by subtype based on fluid compatibility. The valves may be further classified by mounting
8、 style and size/flow rating. See Table 1 for the various classes, types, styles and sizes of thermal relief valves. SAE ARP4835 - 2 - TABLE 1 - CLASSIFICATION OF THERMAL RELIEF VALVES Class System Operating Pressure psi (MPa) 1500 3000 4000 5000 8000 1500 (10.3) 3000 (20.7) 4000 (27.6) 5000 (34.5) 8
9、000 (55.2) Type Temperature Range F (C) I II III IV -65 to +160 -65 to +275 -65 to +450 -40 to +250 (-54 to + 71) (-54 to +135) (-54 to +232) (-40 to +121) Sub Type Fluid Compatibility A B AB Petroleum and Synthetic Hydrocarbon Base (MIL-PRF-5606, MIL-PRF-83282, MIL-PRF-87257) Phosphate Ester Base (
10、AS1241) Compatible with both Subtype A Type I: 71 C (160 F), Type II: 135 C (275 F). NOTE: At manufacturers option, a performance test may be conducted following this test to verify performance before commencing the cyclic impulse test. REQUIREMENT: Flow pressure at rated flow shall not vary more th
11、an 10% from room temperature testing. Leakage shall not exceed two times the room temperature limits. 4.8.5 Endurance 4.8.5.1 Use a test setup to limit the rise rate to 140 MPa/s (20,300 psi/s). The valve shall be cycled between the peak pressure and a minimum pressure not to exceed 1 MPa (145 psi).
12、 4.8.5.2 Return pressure shall be limited to 1 MPa (145 psi) unless otherwise specified in the procurement specification. Minimum peak pressure shall be 135% of the pressure class of the valve as identified in Table 1. 4.8.5.3 A minimum of 4000 cycles shall be run at maximum temperature per Table 1.
13、 4.8.5.4 After every 4000 cycles, rerun flow pressure, repeatability, and reseat tests per 4.8.3 and examine the component under a microscope and note any damage. If any part appears to have failed, discontinue testing. 4.8.5.5 Continue testing until the thermal relief has been cycled 20,000 times.
14、4.8.6 Vibration, Shock and Acceleration 4.8.6.1 The valve shall be subjected to vibration, shock, and acceleration testing per AS4941 or AS8875 as applicable, unless otherwise specified in the purchase order or related documentation. 4.8.6.2 The valve shall meet performance requirements per 4.8.3 af
15、ter vibration tests. SAE ARP4835 - 11 - 4.8.7 Impulse Testing 4.8.7.1 Testing shall be per ARP1383. Any of the pressure wave shapes in ARP1383 may be used. For cycling rates above 2 Hz, verification shall be provided that the required stress level is obtained. 4.8.7.2 The return pressure shall not e
16、xceed 145 psig (1 MPa). 4.8.7.3 Continue testing until the components have been cycled 1,000,000 times. REQUIREMENT: There shall be no rupture or formation of a crack that permits any amount of external leakage of a fluid of 16 mm2/s (centistokes) maximum viscosity at the test pressure of the unit w
17、ithin a 1 min time period. 4.8.8 Burst 4.8.8.1 One valve shall be subjected to a burst test to the pressure listed in Table 1, or 2.5 times the system pressure. It is recommended that the valve not subject to impulse testing be subject to this test. 4.8.8.2 Bleed air from the valve and apply pressur
18、e to the inlet with the outlet plugged. Pressure rise rate shall not exceed 172 MPa (25,000 psi) per minute. Hold pressure for not less than 2 min. 4.8.8.3 The valve shall not rupture but may show permanent deformation and need not pass performance tests after the test. There shall be no rupture or
19、formation of a crack that permits any amount of external leakage of a fluid of 16 mm2/s maximum viscosity at the test pressure of the unit within a 1 min time period. 5. NOTES This section contains information of a general or explanatory nature that may be helpful but is not mandatory. 5.1 Factors A
20、ffecting Test Results 5.1.1 Corrosion inhibitors can affect repeatability of valve closure, therefore MIL-PRF-46170 should not be used as a substitute for MIL-PRF-5606, MIL-PRF-87257 and MIL-PRF-83282 fluids. Laminar valve leakage is inversely proportional to fluid viscosity, and a particular fluids
21、 viscosity is dependent on temperature, pressure, and shear rate. 5.1.2 Fluid particulate contamination can significantly affect the shutoff characteristics of thermal relief valves. Since a large number of particles can exist in clean fluids of a size close to that of the relief valve lift, the pro
22、bability of trapping particles in the seat is high. Trapped particles can produce erratic shutoff performance, with random occurrences of high leakage. Particle silting counteracts this erratic shutoff by causing a decay rate in leakage. Particle silting time for AS4059 Class 5B and higher is from 1
23、 to 3 min; silting may be negligible below AS4059 Class 3B. Contaminant silting can also result in increased poppet friction, which will delay valve opening, resulting in a higher apparent cracking pressure. 5.1.2.1 Random large particles often enter a system during start up or after a connection is
24、 made. The valve may be sensitive to these large particles and should be cycled several times before recording performance. During acceptance testing, dust particles can collect on valves on open benches, and these particles must be flushed through the valve. 5.1.2.2 Pump ripple is the sinusoidal pr
25、essure wave, which is superimposed over the system pressure level, caused by the individual piston pulses from the pump. The amplitude of this wave is influenced by system volume, line lengths, and damping, as well as the condition of the pump. Since the thermal relief responds very rapidly due to i
26、ts dynamic stiffness, it will appear to crack at a lower pressure than statically set, and also have higher leakage at reseat than statically measured. SAE ARP4835 - 12 - 5.2 Key Words High pressure, particulate contamination PREPARED BY SAE SUBCOMMITTEE A-6C, COMPONENTS PANEL OF COMMITTEE A-6, AEROSPACE FLUID POWER, ACTUATION AND CONTROL TECHNOLOGIES
