【2025 Fun Fact】How do flow measurement instruments determine whether to activate a bypass?

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This post was last edited by zhoudingshengs on 2025-1-17 08:56. SH/T 3104-2000 specifies in explicit provisions whether bypasses are required for different flow measurement instruments (see Chapter 5 of SH/T 3104-2000). SH/T 3104-2013 revises the provisions of SH/T 3104-2000; in principle, it does not specify whether a bypass is required for each type of flow measurement instrument, but rather provides guidelines for installing bypasses (see SH/T 3104-2013, Section 7.1.4 and the explanatory notes). Rotary flowmeters are an exception; SH/T 3104-2013 specifies the requirements for bypass installations for rotary flowmeters (see SH/T 3104-2013, 7.12.2). SH/T 3104-2013 \"Code for Installation and Design of Instrumentation in Petrochemical Industries\" 7 Flow Measurement Instruments 7.1 General Requirements 7.1.4 Flow meters shall be equipped with bypass pipelines in accordance with process requirements. The provisions state that 7.1.4 the purpose of installing a bypass pipeline for the flow meter is to ensure that flow measurement is not affected during the removal and maintenance of the flow meter. Therefore, a flow bypass pipeline should be installed in locations where flow measurement is continuous, while it may not be necessary in locations where flow measurement is intermittent; maintenance personnel can then carry out repairs on the flow meter during these intervals when flow is not being measured. 7.1.5 Flow meters used for trade measurement should not be equipped with bypass pipes. For the pipeline layout of the volumetric flowmeter used in trade measurement, refer to Appendix K. 7.12 Rotameter 7.12.1 The rotameter should be installed in a vertical pipe, with the flow direction of the medium being from bottom to top. 7.12.2 Rotameters should be equipped with bypass valves and inlet and outlet isolation valves. SH/T 3104-2000 \"Code for Installation and Design of Instrumentation in Petrochemical Industries\" 5 Flow Measurement Instruments 5.0.3 The installation requirements for rotor flowmeters are as follows: 2 It is advisable to install bypass valves as well as inlet and outlet isolation valves. 5.0.4 The installation requirements for target flowmeters are as follows: 2 It is advisable to install bypass valves and inlet and outlet isolation valves. 5.0.5 The installation requirements for turbine flowmeters are as follows: 3 In cases of continuous operation, bypass valves and inlet and outlet isolation valves should be installed. (Note the prerequisite: in continuous operation scenarios) 5.0.6 The installation requirements for gear and worm gear flow meters are as follows: 2 In continuous operation scenarios, the flow meter should be equipped with a bypass valve and inlet and outlet isolation valves. (Note the prerequisite: in continuous operation scenarios) 5.0.8 The installation requirements for vortex flowmeters are as follows: In locations where the sensing element (vortex generator) may be damaged, vortex flowmeters installed in pipelines should be equipped with inlet and outlet stop valves as well as bypass valves; for insert-type vortex flowmeters, a shut-off ball valve should be installed. (Note the prerequisite: locations where the sensing element (vortex generator) may be damaged) 5.0.9 The installation requirements for mass flow meters are as follows: 8 Mass flow meters should be equipped with inlet and outlet isolation valves as well as bypass valves. 5.0.10 The installation requirements for gas thermal mass flow meters are as follows: 3 An isolation valve should be installed on plug-in gas thermal mass flow meters.