Selection of threaded interfaces for instrumentation equipment
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This post was last edited by Xishan Nan on 2016-11-30 at 16:14. When installing instrumentation equipment, what standard thread sizes are used for all the threaded connections? For example, for pressure gauges, pressure transducers, thermal resistors, thermocouples, instrument air supply ball valves, air supply connectors, electrical interfaces, air supply ball valves, and quick connectors – what type of thread standards are employed to ensure good sealing and ease of replacement? Is it possible to standardize these? Thank you!
Yes, most pressure gauges use M24
1/2npt and M20*1.5 are the more commonly used ones
Your question is too broad; it’s unlikely that many people will be able to answer it in detail. Are you referring to waterproof connectors or the installation interfaces for instruments? For waterproof connectors, the standard size is M20*1.5, though P** sizes are also used. Quick connectors come in sizes such as 1/2, 1/4, 1/8, and so on. Pressure gauges use connections of type G1/2 or NPT, among others. . . . . . . There are also various electrical interfaces. . . .
SH/T 3104 -2013 Code for Installation and Design of Petrochemical Instruments
Most instruments have two interfaces: a process interface and an electrical interface. The manufacturer can be asked to produce it custom-made as needed.
NPT and M threads are the most common.
The explosion-proof cable connectors for MFT instruments are widely used in hazardous environments such as the petrochemical industry, as well as in wiring boxes for peripheral equipment and on-site production control systems, and in the power supply lines for explosion-proof instruments. In the petrochemical sector, these products are renowned for their high quality and superior performance.
There are various options available; the most common ones include 1/2 NPT, M20*1.5, M27*2, etc. It’s important that the specifications on both sides match when making a selection
It’s difficult to standardize, as different manufacturers have varying standards. However, try to do so: for example, change all thermal resistors and thermocouples to armored types, gradually replace the connectors with M16X1.5 types, and substitute the flange connections; as for the electrical connectors, they are hardly needed at all. The pressure gauge should preferably use M20X1.5; since it’s difficult to standardize this, it is determined based on specific needs. However, in the initial design, M20X1.5 and DN40 flanges can be standardized. Even if the interfaces are different, it’s not a major issue.