How to distinguish pressure gauge interfaces
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The pressure gauge interface specified in the drawings provided by the design institute is ZG1/2, while the interface for the instrument data is M20X1.5. The device has arrived; it’s not clear what kind of interface it has, as both ports have the same diameter.
ZG is **a type of thread that is similar to the imperial PT/R/Rc threads: it is a 55-degree sealed tapered thread with a taper ratio of 1:16, and it is primarily used for sealing purposes. Meanwhile, M20*1.5 is a metric thread, mainly used for connection purposes
Meters with M20X1.5 connectors cannot be installed on ZG1/2 pre-installed process connectors.
A simple way to determine this is by looking at it from the side: if the edges at the joint are parallel, it’s an M20; if there is a contraction angle of 1/2 between the two edges.