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1、BRITISH STANDARD AEROSPACE SERIES BS G 240:1988 Specification for Pressure transducers for use on aircraft UDC 629.7.054:531.787 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:31:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS G 240:1988 This British Standa
2、rd, having been prepared under the direction of the Aerospace Standards Committee, was published under the authority of the Board of BSI and comes into effect on 29 February 1988 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference ACE/30 Draft for commen
3、t 87/78805 DC ISBN 0 580 16294 X Committees responsible for this British Standard Civil Aviation Authority (Airworthiness Division) GAMBICA (BEAMA Ltd.) Ministry of Defence Society of British Aerospace Companies Limited Amendments issued since publication Amd. No.Date of issueComments Licensed Copy:
4、 London South Bank University, London South Bank University, Sat Dec 09 02:31:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS G 240:1988 BSI 12-1999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Definitions1 3Information to be supplied in the individual transducer spec
5、ification1 4Classification1 5Construction1 6Output signal2 7Electrical supplies2 8Performance2 9Type tests4 10Production tests5 Table 1 Limits of long-term drift3 Publications referred toInside back cover Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:31:27
6、GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS G 240:1988 ii BSI 12-1999 Foreword This British Standard, having been prepared under the direction of the Aerospace Standards Committee, specifies requirements for pressure transducers for use in aircraft pressure systems. The standard embraces gauge, ab
7、solute and differential pressure units. Pressure transducers produced in accordance with this standard have to be compatible with individual aircraft pressure systems specified by the aircraft manufacturer or the aircraft operator. For each application, the transducer manufacturer produces an indivi
8、dual transducer specification which is called up in the appropriate clauses of this standard. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does n
9、ot of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This
10、will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:31:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS G 240:1988 BSI 12-19991 1 Scope This British Standard specifies requirements for pressure t
11、ransducers used in aircraft pressure systems, to convert a fluid pressure into an electrical signal for transmission to aircraft indicators or systems. It is applicable to transducers capable of measuring gauge, absolute or differential pressure, that have an accuracy in the range 0.25 % to 2.0 % of
12、 full scale output at reference conditions, and are capable of working over the ambient temperature range 54 C to + 85 C. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this British Standard the following definit
13、ions apply. 2.1 transducer a fluid pressure sensor that provides electrical output signals 2.2 proof pressure of the transducer the maximum pressure at which there is no permanent calibration change or leakage 3 Information to be supplied in the individual transducer specification For the purposes o
14、f compliance with this standard the individual transducer specification shall contain the following information: a) details of pipe connections (see 5.5); b) details of materials used in the manufacture of the transducer that are in contact with the pressure fluid (see 5.9); c) output signal charact
15、eristics (see 6.1); d) characteristics of low voltage d.c. supplies needed to operate the transducer (see 7.2); e) output signal error limits in the mounting attitude (see 8.5); f) response time (see 8.6); g) effect on performance when fluid temperature differs significantly from the ambient tempera
16、ture (see 8.8.3); h) initial stabilization time (see 8.9.2); i) compass safe distance (see 8.11); j) acceleration class (see 8.15); k) severity grade for salt mist test, i.e. 1 or 2 (see 8.16); l) requirements for resistance to fluid contamination (see 8.18); m) requirements for electrical insulatio
17、n resistance (see 8.19); n) power supply variation, if other than that specified in BS 3G 100-3 (see 8.21); o) mounting attitude for the accuracy test (see 9.1); p) frequency range for the vibration test (see 9.12); q) sampling procedure for quality tests (see 10.2). 4 Classification Transducers are
18、 classified into three types as follows: a) high accuracy (type HA): high accuracy units for specialized application, e.g. flight test measurement; b) medium accuracy (type MA): medium accuracy units for applications where high accuracy is not required, e.g. flight management systems; b) low accurac
19、y (type LA): lower accuracy output for general aircraft applications, e.g. flight deck gauges. 5 Construction 5.1 The proof pressure of the transducer shall be not less than 1.5 times the rated operating pressure. 5.2 The burst pressure of the pressurized components shall be not less than 2.0 times
20、the rated operating pressure of the transducer. 5.3 The burst pressure of the case shall be not less than 3.0 times the rated operating pressure of the transducer or 3 bar gauge, whichever is the greater (but see 5.11). 5.4 In vented gauge transducers means shall be provided to vent the pressurized
21、fluid in a safe manner if the pressurized element ruptures. 5.5 Pipe connections shall be as stated in the individual transducer specification. 5.6 Where more than one pipe connection is used, they shall be positively identified to minimize the risk of incorrect connection. NOTESome applications wil
22、l require mechanically non-interchangeable connections as stated in the individual contract or order. 5.7 The case strains caused by mounting and/or pipe connections shall not affect the performance of the transducer as specified in 8.1. 5.8 Electrical connections shall be as far removed as possible
23、 from the pressure connector(s) to minimize the risk of contamination by the pressure fluid. Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:31:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS G 240:1988 2 BSI 12-1999 5.9 All materials used in the manufacture
24、 of the pressure transducer that are in contact with the pressure fluid shall be stated in the individual transducer specification. 5.10 When tested in accordance with BS 2011-2.1 Pz, pressure transducers containing significant quantities of non-metallic materials shall be shown not to support combu
25、stion, nor emit significant quantities of smoke or toxic fumes. 5.11 If the pressure transducer is designed to be installed in a location where it may come into contact with flammable vapours, it shall comply with BS 3G 100-2.3.5. 6 Output signal 6.1 The transducer output signal shall be in one of t
26、he following forms: a) resistive potentiometer; b) synchro angle; c) frequency change; d) high level voltage output of 0 V to 5 V d.c., or 0 V to 10 V d.c., that can be operated into the minimum load impedance as stated in the individual transducer specification; e) low level voltage output of at le
27、ast 20 mV full range output with 10 V d.c. excitation, when operating into the minimum load impedance as stated in the individual transducer specification; f) current output of 0 mA to 1 mA, 0 mA to 10 mA or 4 mA to 20 mA; g) digital, with characteristics as stated in the individual transduce specif
28、ication. 6.2 Short circuit protection shall be included in the output signal circuit for transducers except where the transducer is inherently protected by design, or is of low level voltage output see 6.1 e). NOTEThe individual transducer specification should state the maximum value of extraneous v
29、oltage produced by the transducer in the form of common mode. It should also state whether or not either of the signal lines can be connected to the appropriate power supply line. 7 Electrical supplies 7.1 The transducer shall be designed to operate from any one of the following: a) 115 V single pha
30、se a.c. 400 Hz and supplies derived therefrom; b) 28 V d.c.; c) low voltage d.c. 7.2 The characteristics of the electrical supplies given in 7.1 a) and b) shall be as specified in BS 3G 100-3. The characteristics of low voltage d.c. supplies shall be as stated in the individual transducer specificat
31、ion. 7.3 The transducer shall be protected against damage caused by incorrect polarity power supply connection. 8 Performance 8.1 Accuracy When tested in accordance with 9.1, the transducer output accuracy, including the errors due to combined effect of hysteresis, repeatability, resolution and non-
32、compliance with the design calibration, shall be within the following tolerance bands: type HA: 0.25 % of full scale output; type MA: 1.0 % of full scale output; type LA: 2.0 % of full scale output. NOTEThe overall transducer accuracy may be calculated by combining the components of error by the roo
33、t-sum-squared (RSS) method. 8.2 Altitude When tested in accordance with 9.2, the transducer output signal shall comply with 8.1. 8.3 Overpressure When tested in accordance with 9.3, the transducer output signal shall comply with 8.1. 8.4 Case burst pressure When tested in accordance with 9.4, the ca
34、se shall not leak or burst. 8.5 Mounting attitude When tested in accordance with 9.5, the transducer output signal errors shall either not exceed the requirements of 8.1 by more than 0.1 % of the full scale output per g1) or comply with the limits stated in the individual transducer specification. 8
35、.6 Response time When tested in accordance with 9.6, the transducer output signal shall achieve 63 % of the signal corresponding to the step pressure input within the time stated in the individual transducer specification. 1) g is the acceleration due to gravity. Licensed Copy: London South Bank Uni
36、versity, London South Bank University, Sat Dec 09 02:31:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS G 240:1988 BSI 12-19993 8.7 Damping When tested in accordance with 9.7, the transducer output signal shall achieve a steady state corresponding to the input within two overshoots. NOTETransducers
37、 used with incompressible fluids and subjected to overpressure pulses with high pressure rise rates may require special consideration of their damping characteristics. 8.8 Temperature 8.8.1 When tested in accordance with 9.8, the transducer output total error band, due to the combined effects of 8.1
38、, plus thermal zero and sensitivity shifts and thermal hysteresis, over the temperature range 54 C to + 85 C, shall not exceed: type HA: 0.8 % of full scale output; type MA: 1.75 % of full scale output; type LA: 3.5 % of full scale output. 8.8.2 The transducer shall not be deranged by exposure to te
39、mperatures between 70 C and + 90 C when energized. 8.8.3 Where the temperature of the pressurized fluid differs significantly from the ambient temperature, the effect on the performance of the transducer shall be as stated in the individual transducer specification. 8.9 Long-term stability 8.9.1 Whe
40、n tested in accordance with 9.9, the long-term drift due to cumulative errors from all internal sources shall not exceed the values given in Table 1 without readjustment for a period of 30 days. 8.9.2 The time required for initial stabilization of the transducer shall be as stated in the individual
41、transducer specification. Table 1 Limits of long-term drift 8.10 Endurance When tested in accordance with 9.10, the transducer output signal shall comply with 8.1. 8.11 Compass safe distance When tested in accordance with 9.11, the transducer compass safe distance shall be as stated in the individua
42、l transducer specification. 8.12 Vibration 8.12.1 When tested in accordance with 9.12, the error of the transducer due to vibration, at the g levels of the sinusoidal vibration test, in its most sensitive axis shall not exceed 0.1 % of the full range output per g. 8.12.2 At the conclusion of the tes
43、t, the transducer shall not have suffered damage and the output signal shall comply with 8.1 without adjustment. 8.13 Temperature-pressure When tested in accordance with 9.13, the performance of the transducer shall not be impaired. 8.14 Mould growth When tested in accordance with 9.14, the transduc
44、er shall exhibit no mould growth. 8.15 Acceleration 8.15.1 When tested in accordance with 9.15, the error of the transducer output signal, due to acceleration up to the maximum test g level, in its most sensitive axis shall not exceed 0.1 % of the full range output per g. 8.15.2 At the conclusion of
45、 the test, the transducer shall not have suffered damage and the output signal shall comply with 8.1 without adjustment. NOTEThe acceleration class should be stated in the individual transducer specification. 8.16 Salt mist When tested in accordance with 9.16, the transducer shall not be damaged by
46、salt mist at the severity rating stated in the individual transducer specification. 8.17 Waterproofness When tested in accordance with 9.17, the transducer output signal shall comply with 8.1 both during and after the test. 8.18 Fluid contamination When tested in accordance with 9.18, the transducer
47、 shall comply with the requirements for fluid contamination resistance stated in the individual transducer specification. 8.19 Insulation resistance When tested in accordance with 9.19, the insulation resistance of the power supply to case and output to case shall be as stated in the individual tran
48、sducer specification. Accuracy class Limits of long-term drift: percentage of full-range output Type HA Type MA Type LA % 0.05 0.10 0.25 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 02:31:27 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS G 240:1988 4 BSI 12-19
49、99 8.20 Radio interference 8.20.1 When tested in accordance with 9.20, the transducer output shall be unaffected by the radiated and conducted interference as specified in BS 3G 100-4.2. 8.20.2 The radiated and conducted interference exported by the transducer shall be within the limits specified in BS 3G 100-4.2. 8.21 Effect of power supply variation The transducer output signal shall comply with 8.1 under power supply variation as stated in BS 3G 100-3, or as stated in the individual transducer specification. 9 Type tests 9.1 Accuracy t
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