NPT Swivel to Pressure Gage Fitting Question

[Gordon Gould]

I wanted to put a 1/4 NPT Pressure gauge on a NPT swivel fitting to allow easy angle adjustment of the gauge but when I got the parts and looked at them I am not sure it will seal. The gauge stub is flat like a plug and it will sit on top of the cone in the female swivel. The gauge bottoms out in the swivel after only 2 threads are turned in. Will this seal ???
I know I could add a nipple and coupling between the swivel and the gauge but don't really want the extra height.
Thanks for any suggestions.

 

[RickB]

It's not going to seal.

 

[bandaidmd]

"Will this seal ???" No
You can just use a standard hardware street ell or a Hyd nipple and coupler like you alluded too. a nipple that is designed for hydraulics has the tapered seat on the inside and standard tapered pipe threads on the outside.

 

[SPYDERLK]

I see the mark the cone tip has made and its far enuf away from the gage hole and its threads that distortion of the gage nipple under tightening should not be an issue. Two threads on brass is marginal, but be sure the cone tip is smooth. If it is orthogonal to the assembly axis it should seal readily. Under tightening the cone tip will displace the brass a little and seal. I dont see any other choice to get what you want. Be nice to have another thread engagement, but yould have to machine the cone tip to get it. Doing that and preserving the critical alignment is tricky.
larry

 

[Gordon Gould]

Thanks Gents - you have told me what I need to know. As tempting as it is to just try what I have and hope for the best I think plan B will be to use a standard Street Elbow. That will give my a solid joint. I would hate to spring an unnecessary leak in the middle of a job somewher away from home.

 

[Zebrafive]

I am also building a pressure gauge set up. I plan to use a hose with a female JIC swivel end. The adapter from the hose to the gauge will be male JIC to female NPT.

 

[J_J]

Built by TBN members.

 

[sparc]

I wanted to put a 1/4 NPT Pressure gauge on a NPT swivel fitting to allow easy angle adjustment of the gauge but when I got the parts and looked at them I am not sure it will seal. The gauge stub is flat like a plug and it will sit on top of the cone in the female swivel. The gauge bottoms out in the swivel after only 2 threads are turned in. Will this seal ???
I know I could add a nipple and coupling between the swivel and the gauge but don't really want the extra height.
Thanks for any suggestions.

These two style connections are not designed to mate up and any attempt to use the two will result in a leak or worse a failure under pressure which could be hazardous to anyone in the vicinity when it lets go.

Use a service or street ell along with the proper adapter fitting to transition from one style connection to the other.

Many gauges (but maybe a little tougher to find in the smaller size gauges like 2" or 2.5") are available with a 1/4" back mount (as opposed to the bottom mount you show in the photo) which might eliminate the need for one fitting depending on how you are mounting and viewing the gauge.

 

[SPYDERLK]

These two style connections are not designed to mate up and any attempt to use the two will result in a leak or worse a failure under pressure which could be hazardous to anyone in the vicinity when it lets go.

True. They are not. However the application is within the window where it is likely to work if alighnment is right-- and thats a cinch to determine just by assembly. The remote possibility of failure of an assembly that sealed readily could be addressed by a critical orifice in the inlet of the EL. Indeed all gages should be thus restricted routinely to eliminate danger occurring if the Bourdon tube fatigues or fails otherwise.
larry

 

[RickB]

Permently mounting a $20 bourdon tube style gauge on a piece of mobile machinery is pretty much asking for a major leak sooner or later regardless how the fittings match up.