KENYA BUREAU OF STANDARDS (KEBS)

Transcription

1 CD13/SERV/ 2018 DRAFT KENYA STANDARD Dial thermometers - Specification Public Review Draft March 2018 KENYA BUREAU OF STANDARDS (KEBS)

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3 WORKING GROUP REPRESENTATION The following organizations were represented on the Technical Committee. Association of Persons living with Disability of Kenya (APDK) Christian Health Association of Kenya (CHAK) Nairobi County Ministry Of Health Kenyatta National Hospital (KNH) Nursing Council of Kenya (NCK) Kenya Bureau of Standards (KEBS) - Secretariat REVISION OF KENYA STANDARDS In order to keep abreast of progress in industry, Kenya Standards shall be regularly reviewed. Suggestions for improvements to published standards, addressed to the Managing Director, Kenya Bureau of Standards are welcome. Kenya Bureau of Standards, 2018 Copyright. Users are reminded that by virtue of section 6 of the Copyright Act, Cap. 130 of the laws of Kenya, copyright subsists in all Kenya Standards and except as provided under section 7 of this Act, no Kenya Standard produced by Kenya Bureau of Standards may be reproduced, stored in a retrieval system in any form or transmitted by any means without prior permission in writing from the Managing Director.

4 DRAFT KENYA STANDARD Dial thermometers - Specification KENYA BUREAU OF STANDARDS (KEBS) Head Office: P.O. Box 54974, Nairobi-00200, Tel.: ( ) , , Fax: ( ) info@kebs.org, Web: Cost Region Lake Region North Rift Region P.O. Box 99376, Mombasa P.O. Box 2949, Kisumu P.O. Box 2138, Nakuru Tel.: ( ) , /40 Tel.: ( ) 23549, Tel.: ( ) , Fax: ( ) Fax: ( ) Fax: ( ) kebs_msa@swiftmombasa.com kebs_ksm@swiftkisumu.com

5 Foreword Kenya Bureau of Standards is a national standards body (NSB). The work of preparing Kenya Standards is normally carried out through national technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. National organizations, governmental and non-governmental, in liaison with KEBS, also take part in the work. Kenya Standards are drafted in accordance with the rules given in the KS ISO/IEC Directives, Part 2. The main task of technical committees is to prepare National Standards. Draft Kenya Standards adopted by the technical committees are circulated to the technical committee members for balloting. Publication as a Kenya Standard requires approval by at least 2/3 of the members casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. KEBS shall not be held responsible for identifying any or all such patent rights. This Kenya Standard was prepared by Technical Committee KEBS/TC 136, Medical Tools, devices and Equipment. During the development of this standard, reference was made to the following documents. EN 13190:2001, Dial thermometers. This assistance is hereby acknowledged.

6 KENYA STANDARD Dial thermometers - Specifications 1. Scope This Kenya Standard specifies requirements and testing for indicating thermometers using sensing methods of gas expansion (symbol GE), liquid expansion (symbol LE) and bimetallic strip (symbol BM). Nominal sizes are from 40 to 160, and temperature measurement from 100 ºC to +700 ºC. Thermometers specified have circular scales, and are for industrial use only. Thermometers of square form are also covered by this Kenya Standard except for case and pointer dimensions. Annex A includes recommendations for selection and installation. This standard does not apply to thermometers for medical use nor to thermometers with electrical limit contact devices 2. Terms and definitions For the purpose of this standard, the following terms and definitions apply. 2.1 dial indicating thermometer instrument consisting of head and temperature detecting element or stem connected together by a rigid stem or, except for bimetallic thermometer, by a flexible capillary. 2.2 bimetallic thermometer dial indicating thermometer operated by differential expansion strip, helix or coil. 2.3 gas expansion thermometer (GE) dial indicating thermometer operating on the principle of change in pressure of a fixed volume of gas in response to temperature change. 2.4 liquid expansion thermometer (LE) dial indicating thermometer operating the principle of liquid volume expansion in response to temperature change. 2.5 temperature detecting element that part of a thermometer which supports and includes the sensitive portion. 2.6 sensitive portion of temperature detecting element that part of the temperature detecting element which contains the major portion of the temperature sensitive fluid or bimetal strip. 2.7 thermometer insertion length distance the temperature detecting element is inserted into process medium 2.8 thermometer movement assembly by means of which the expansion of the fluid used or bimetallic strip are transformed and enlarged into an angular variation

7 2.9 thermometer connection part by which the dial indicating thermometer can be coupled to the temperature tapping of the plant, pipework or equipment 2.10 thermometer compensation apparatus fitted inside head and/or capillary to minimize errors due to ambient temperature variations adjustable pointer pointer with an adjustable device 2.12 thermometer nominal size conventional alpha-numerical designation relating to the size of the thermometer 3 Nominal sizes Nominal sizes of the thermometers are as follows: 40, 50, 63, 80, 100, 130, 150 and 160 mm (see table 1 for dimensions). 4 Nominal ranges The degree Celsius abbreviated to ºC is the preferred unit of temperature measurement. The following nominal ranges are specified: From 0 ºC to 60 ºC From -20 ºC to +40 ºC From 0 ºC to 80 ºC From -20 ºC to +60 ºC From 0 ºC to 100 ºC From -20 ºC to 120 ºC From 0 ºC to 120 ºC From -30 ºC to +30 ºC From 0 ºC to 160 ºC From -30 ºC to +50 ºC From 0 ºC to 200 ºC From -30 ºC to +70 ºC From 0 ºC to 250 ºC From -40 ºC to +40 ºC From 0 ºC to 300 ºC From -40 ºC to +60 ºC From 0 ºC to 400 ºC From -100 ºC to +60 ºC From 0 ºC to 500 ºC From 0 ºC to 600 ºC From 0 ºC to 700 ºC From 50 ºC to 650 ºC From 100 ºC to 700 ºC NOTE Not all types of thermometers are suitable for all ranges ( also see Table A.1). 5 Accuracy classes The following accuracy classes are defined: class 1 and class 2. Class 1 may be used with nominal sizes 63 to 160, class 2 may be used with nominal sizes 40 to Dimensions 6.1 General tolerance General tolerances: Tolerance class m according to

8 6.2 Cases and flanges The user will have to determine the dimensions for panel cut-out according to the manufacturer s data. Figure 1 Dimensions of thermometer cases and flanges Nominal d 1 min. d 2, max. size Mm mm d 4 d 5 mm mm NOTE: Elongated holes can be accepted to ensure interchangeability with previous standards 6.3 Thermometer connection The type of connections in figure 2 are used for both rigid stem thermometers and thermometers with capillarity. The connections in figure 3 are for rigid stem thermometers only. The length of l 5 of thermometers connection form 4 depends on the length of the threaded part of its thermowell and shall be longer than the latter. The minimum height of the hexagon, square or flats shall be compatible with the use of standard spanners according to KS ISO Screw threads Parallel pipe threads (symbol G) according to KS ISO Taper pipe threads (symbol NPT) according to ANSI/ASME B ISO general purpose metric screw threads (symbol M) having basic profile according to KS ISO Other threads specific to certain industries are acceptable Temperature detecting element The diameter of the temperature detecting element d 5 and its length l 1 (see figures 2 and 3) will be at manufacturer s discretion or should be by agreement between purchaser and supplier Sensitive portion of the thermometer detecting element The length of the sensitive portion of the temperature detecting element l 2 (see figures 2 and 3) shall be stated by manufacturer. 7 Requirements The test methods for these requirements are given in clause 9.

9 7.1 Accuracy The limits of error in Table 5 correspond to the measuring range of the thermometer and shall apply in the range ± 2 ºC above and below the reference value given for the ambient temperature and for the mounting attitude specified in 7.5. The hysteresis error shall not exceed half value specified for the limits of error in Table 5. The measuring range of dial thermometers is set of values of the measurand for which the errors of measurement must lie within the specified or agreed limits of error. It is a part of the nominal range and may be coincident with it.