1、BS ISO27892:2010ICS 23.160NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDVacuum technology Turbomolecular pumps Measurement ofrapid shutdown torqueThis British Standardwas published under theauthority of the StandardsPolicy and StrategyCommittee on 28 February2
2、010 BSI 2010ISBN 978 0 580 62194 9Amendments/corrigenda issued since publicationDate CommentsBS ISO 27892:2010National forewordThis British Standard is the UK implementation of ISO 27892:2010.The UK participation in its preparation was entrusted to TechnicalCommittee MCE/8/-/4, Vacuum technology.A l
3、ist of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal
4、obligations.BS ISO 27892:2010Reference numberISO 27892:2010(E)ISO 2010INTERNATIONAL STANDARD ISO27892First edition2010-02-01Vacuum technology Turbomolecular pumps Measurement of rapid shutdown torque Technique du vide Pompes turbomolculaires Mesurage du couple darrt rapide BS ISO 27892:2010ISO 27892
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9、s below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2010 All rights reservedBS ISO 27892:2010ISO 27892:2010(E) ISO 2010
10、 All rights reserved iiiContents Page Foreword iv Introduction.v 1 Scope1 2 Normative references1 3 Terms and definitions .1 4 Symbols, definitions, and units .2 5 Destructive test methods for turbomolecular pumps .3 5.1 General .3 5.2 Items to be checked 3 5.3 Test conditions for burst and crash (f
11、ailure of rotor body and rotor blades).3 5.4 Destructive test equipment 7 5.5 Destructive test procedures.8 5.6 “Crash” destructive test method (failure of rotor or stator blades).9 6 Test report14 Annex A (informative) Details to be stated in technical drawings and documents .15 Bibliography16 BS I
12、SO 27892:2010ISO 27892:2010(E) iv ISO 2010 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical comm
13、ittees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
14、International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft Internation
15、al Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be th
16、e subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 27892 was prepared by Technical Committee ISO/TC 112, Vacuum technology. BS ISO 27892:2010ISO 27892:2010(E) ISO 2010 All rights reserved vIntroduction A rotating turbomolecular pump or mo
17、lecular drag pump has a large amount of energy stored in the rotor due to the high rotational frequency. If the rotor breaks, this energy is released in a very short time and there is the possibility of rupture of the casing of the turbomolecular pump. A large reaction torque is also generated on th
18、e pump housing and there is a possibility that the bolts that fix the turbomolecular pump might break. This International Standard is based on results compiled in studies of these possibilities and has been drafted as a measurement method by turbomolecular pump manufacturers with the aim of improvin
19、g the safety of users. The core contents of this International Standard are the test methods for rapid shutdown torque measurement of turbomolecular pumps and molecular drag pumps. The term “turbomolecular pump” used in this International Standard is generic and includes molecular drag pumps and pum
20、ps which contain both technologies on the same shaft. BS ISO 27892:2010BS ISO 27892:2010INTERNATIONAL STANDARD ISO 27892:2010(E) ISO 2010 All rights reserved 1Vacuum technology Turbomolecular pumps Measurement of rapid shutdown torque 1 Scope This International Standard specifies a method for the me
21、asurement of rapid shutdown torque (destructive torque) of turbomolecular pumps in which gas momentum is produced by axial flow type blades and/or helical channels. The main forces leading to failure of turbomolecular pumps are torques around the rotational axis. Other insignificant forces and momen
22、ts that can occur lie outside the scope of this International Standard. There are two kinds of failure: rapid shutdown by whole burst and softer crash of rotor. This International Standard applies to both. The same measurement method can be used for turbomolecular pumps and molecular drag pumps. 2 N
23、ormative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 3529-2, Vacuum technology
24、 Vocabulary Part 2: Vacuum pumps and related terms 3 Terms and definitions For the purpose of this document, the terms and definitions given in ISO 3529-2 and the following apply. 3.1 inlet flange turbomolecular pump inlet suction flange for connecting and fitting on to the vacuum vessel that is to
25、be evacuated 3.2 rotor rotational body rotational parts vacuum pumps assembly, composed of shaft, rotor body and rotor blades, which is supported by bearings and is driven by a motor 3.3 rotor blade turbine blade rotating blade vacuum pumps part of a pump which rotates with a peripheral speed close
26、to the speed of sound and which imparts a vacuum exhaust action to the pump, analogous to axial flow type turbine blades BS ISO 27892:2010ISO 27892:2010(E) 2 ISO 2010 All rights reserved3.4 rotor body cylinder part of rotor rotor hub vacuum pumps rotor assembly excluding the rotor blades 3.5 centrif
27、ugal destruction split caused by centrifugal force rupture caused by centrifugal force failure occurring in the rotor body through circumferential tensile stress above the marginal value due to the centrifugal force acting on the rotor when operating 3.6 destructive test rotor destructive test test
28、of the safety of the turbomolecular pump body and measurement of the destructive torque by causing the rotor body of the turbomolecular pump (burst test) or the rotor blades of the turbomolecular pump (crash test) to fail 3.7 destructive rotational frequency rotational frequency of the rotor when th
29、e rotor body fails in the test 3.8 notch machining machining carried out on all or a part of the rotor prior to destructive testing to form a notch so that an appropriate stress concentration occurs in the rotor body so that failure occurs in the vicinity of the rated rotational frequency separately
30、 stipulated for the rotor body during destructive testing 3.9 destructive torque shutdown torque rapid shutdown torque rotational torque acting on or transmitted to the inlet flange fixing member side or base fixing side during failure of the rotor body by centrifugal force in destructive testing 4
31、Symbols, definitions, and units Symbol Definition Unit A Cross-section of compression bar m2d1Internal diameter of short tube m d2External diameter of short tube m E Young modulus of elasticity of lengthwise direction of compression bar Pa FnMeasured force N G Modulus of rigidity of short tube Pa Ip
32、Initial moment of inertia of rotor around rotational axis kg m2i Compression bar number or force sensor number n Rotational frequency Hz r Location radius of compression bar or force sensor m T Rapid shutdown torque Nm t Time s Measured strain Angular velocity rad/s BS ISO 27892:2010ISO 27892:2010(E
33、) ISO 2010 All rights reserved 35 Destructive test methods for turbomolecular pumps 5.1 General There are two kinds of failure: rapid shutdown by whole burst and softer crash of rotor. Pumps are fixed either at the inlet flange or the pump base. There are thus two kinds of destructive test equipment
34、 (see 5.4). The more suitable test method should be selected by the manufacturer based on the intended use of the product. 5.2 Items to be checked WARNING The destructive tests listed below are dangerous and adequate safety measures should be taken when carrying them out. To ensure safety, measure r
35、apid shutdown torque. This method is the only recommended method. The torque obtained by this method is not always the maximum value, but one value. Check the following items: a) the value of the destructive torque; b) that the pump mounting uses the stipulated fitting and is safe; c) that the pump
36、housing is safe. 5.3 Test conditions for burst and crash (failure of rotor body and rotor blades) The destructive test conditions are as follows. 5.3.1 Destructive test method (burst) 5.3.1.1 The rotor is deemed to fail when the rotor body or the main shaft fails. 5.3.1.2 The procedure involves notc
37、h machining of the rotor body or main shaft so that the rotor body fails by centrifugal or external (e.g. a “crash” destructive test method in which rotor or stator blades fail) force in the vicinity of the rated speed. The notch in the main shaft should be located between the rotating motor and the
38、 rotor mounting. 5.3.1.3 Make the notch with four or fewer divisions. 5.3.1.4 The rotational frequency at failure should preferably be within 5 % of the rated rotational frequency. NOTE This International Standard does not make stipulations with regard to the division method of rotor body failure in
39、 destructive testing. 5.3.2 Torque cell 5.3.2.1 General There are two types of torque cell, either consisting of a short tube with strain gauges (5.3.2.2) or a stand with compression bars (5.3.2.3). The compression bars have strain gauges or force sensors attached to them. If a torque cell is used,
40、ensure that plastic deformation of the cell does not occur. BS ISO 27892:2010ISO 27892:2010(E) 4 ISO 2010 All rights reserved5.3.2.2 Short tube type 5.3.2.2.1 The torque on the cell is measured by strain gauges, which are fitted to the central part of the short tube, as shown in Figure 1. The strain
41、 gauges are installed diametrically opposite one another. Figure 2 shows strain gauges in eight places (four sets) at a pitch of 30. Other examples are shown in Figures 3 and 4. To ensure adequate responsiveness of the measurement system, it is desirable to use gauges with a range of 0 Hz to 10 kHz
42、or more. 5.3.2.2.2 The destructive torque is calculated from the mean value of strain around the circumference at the time of failure. The relation between torque, T, in newton metres, and strain is given by Equation (1). ()442128GddTd = (1) where is the measured strain whose direction is at 45 with
43、 respect to the axis of the torque cell; d1is the internal diameter, in metres, of the short tube; d2is the external diameter, in metres, of the short tube; G is the shearing modulus of rigidity, in pascals, of the short tube. Key 1 short tube with strain gauges 2 amplifier for strain gauges 3 data
44、recorder 4 strain gauges Figure 1 Short tube with strain gauges Figure 2 Example of a pitch of 30, eight places (four sets) BS ISO 27892:2010ISO 27892:2010(E) ISO 2010 All rights reserved 5Figure 3 Example of two places (one set) Figure 4 Example of a pitch of 60, six places (three sets) 5.3.2.3 Com
45、pression bar type 5.3.2.3.1 Compression bars are provided on a stand (see Figure 5) in the direction of action of the pump destructive torque. The bars are set up so that strain gauges or force sensors are compressed by the pump destructive torque. Compression bars with strain gauges are also known
46、as strain rods. The strain rods or the force sensor are fixed to the floor or a base plate by fasteners such as anchor bolts that have sufficient strength. 5.3.2.3.2 The measurement gauge used for the compression bar torque cell is a strain gauge or a force sensor. The strain gauges or force sensors
47、 are installed on the compression bars as in 5.3.2.3.1. It is desirable to install compression bars at two to four places at equal intervals around the circumference. To ensure adequate responsiveness of the measurement system, it is desirable to use strain gauges or force sensors with a range of 0
48、Hz to 10 kHz or more. 5.3.2.3.3 The destructive torque is calculated from the sum of strain or force at the two to four places at the time of failure. For strain gauges, the torque, T, in newton metres, is related to strain by Equation (2): ()1. iTEAr=+ (2) where iis the measured strain; A is the cr
49、oss-sectional area, in square metres, of the compression bar; E is the Young modulus of elasticity, in pascals, of the lengthwise direction of the compression bar; i is the strain rod number; r is the compression bar location radius, in metres. BS ISO 27892:2010ISO 27892:2010(E) 6 ISO 2010 All rights reservedFor force sensors, the torque, T, in newton metres, is related to total force by Equation (3): ()1. iTrF F=+ (3) where Fiis the measured force, in newtons; i is the force sensor number
