Pressure Gauge connection Type

[Drake85]

Hello, I have been asked at work to check for info that would simplify the recognition of the thread dimension of a device.
For example consider a pressure gauge like the one in the pic (taken from the internet), the possible threads to be used are given by the ASME B40.100, that refers to the B1.20.1 for thread definition.
I cannot find however the dimensions of the tightening "nut" that will be used with a wrench. I was looking for a standard that would pair NPT size to the width of this "nut", this way identifying the size would be much faster. I tend to believe that the dimensions would be the same of the ones of the bolts/nuts but i would like to ask for your opinion/experience
Now i will try to aswer possible questions:
- Why don't you just measure the pipe? Sometimes the devices are not connected to a pipe
- Why don't you just ask for the information at the deposit? Some sites are lacking this kind of information
- Why are you looking in the B40.100 standard? Because the EN 837-1 gives this kind of information and was looking for the ASME counterpart

Hope you can help me, if you have other ways to identify this kind of info in your experience i will be more than happy to hear it.

I wish you an excellent day

 

[Stick.]

Would something like this work for what you need? I have the pocket version and it's pretty handy.

Thread Identification Kits | Gates Corporation

From hydraulic system adjustment and maintenance to making factory-quality assemblies on the field, Gates manufactures hydraulic equipment and hose crimpers to improve your operational capacity and system service life with ease. Cut through tough hoses with portable Power Cutter and Gates hose...

www.gates.com

 

[danw2]

The last copy of B40.100 (2005) I saw did not specify square or hex dimensions on the gauge stem.

The spec sheet for any particular brand/model gauge probably provides the spec, but you need to know the brand and model, not always evident for installed gauges.

 

[Drake85]

Would something like this work for what you need? I have the pocket version and it's pretty handy.

Thread Identification Kits | Gates Corporation

From hydraulic system adjustment and maintenance to making factory-quality assemblies on the field, Gates manufactures hydraulic equipment and hose crimpers to improve your operational capacity and system service life with ease. Cut through tough hoses with portable Power Cutter and Gates hose...

www.gates.com

Thanks for the answer, very interesting didn't know about this kit. The fact is that I was looking if there is a way to identify the size without unscrewing the device.

The last copy of B40.100 (2005) I saw did not specify square or hex dimensions on the gauge stem.

The spec sheet for any particular brand/model gauge probably provides the spec, but you need to know the brand and model, not always evident for installed gauges.

Yes, i couldn't find it either, so I was wondering if there was a standard that states the min. dimensions of the tightening section (as it is for bolts and nuts). There must be surely a minimum size.
Per comparison here you can see the EN standard:


Edit:

@danw2 looking at the spec sheet you posted, i'm thinking it will be anyway useless to know the minimum size since, for example, the one you posted have the same tightening size so it would be impossible to know without unscrewing it.
At this time the only hope is that someone else knows something different that could help the identification