DKE German Commission for Electrical, Electronic & Information Technologies of DIN and VDE
DIN 43772 Beiblatt 2
Control technology - Protective tubes and extension tubes for liquid-in-glass thermometers, indicating mechanical thermometers, thermocouples and resistance thermometers; Supplement 2: Calculation of protective tubes
Leittechnik - Metall-Schutzrohre und Halsrohre für Maschinen-Glasthermometer, Zeigerthermometer, Thermoelemente und Widerstandsthermometer; Beiblatt 2: Berechnung von Schutzrohren
Overview
This Supplement contains technical guidelines and information for calculating the mechanical and thermal strength of thermometer protection tubes. The load on thermometer protection tubes can be estimated using the load diagrams for static loads specified in DIN 43772:2000-03, Annex A. Information on critical speeds with regard to dynamic loads caused by vibration can be found in DIN 43772:2000-03, Table A.1. The mechanical-thermal strength for deviating protective tube geometries can be calculated using this Supplement. It should be noted that the principles and results of this calculation can only be compared to a limited extent with those from the ASME PTC 19.3 TW-2016 (Performance Test Code), as the validity of PTC 19.3 is limited to single-piece protective tubes in international design (ASME B40.9) and therefore does not include protective tubes of forms 1-9 described in DIN 43772. A revised version of ASME PTC 19.3 TW-2010 has been published in 2016. The standard differs from DIN 43772 Supplement 2:2015-06 as follows: a) calculation examples with parameters relevant to practice have been included; b) the text has been revised for better comprehensibility and clarity. This Supplement 2 has been prepared in order to provide users with a practical method for calculating the mechanical/thermal protective tube characteristics. The calculation is illustrated using specific examples from practice. The examples are divided into three areas: - calculation of a single-piece protective tube, form 4 (static analysis according to P. Dittrich) [1] (see 8.2); - calculation of a multi-part protective tube, form 2G (static analysis according to P. Dittrich) [1] (see 8.3); - calculation of a multi-part protective tube, form 2G (dynamic analysis, see 8.4, - recommended in addition to static analysis).
