5

I have a pressure gauge which threads onto a hose bib. I am trying to have the pressure gauge end up facing upwards in a readable position. Every time I try to start the thread at a different position such that the number of turns would have the readable face of the pressure gauge in the correct orientation it finishes at the exact same place.

Is the problem that the male thread will always start thread at the exact same spot on the female threaded piece?

I've managed to spin the hose bib such that the pressure gauge is in the correct position but I have two manifold shutoffs that have temperature gauges which are in a similar state and since I didn't have much luck with the hose bib I worry I won't be able to adjust their orientation.

manifold shutoff with upside down temperature gauge

The only piece I am looking to change the orientation of is the temperature well. It does seem to have two nuts on the back so hopefully it does spin independently of the thread orientation.

temperature well

Fresh Codemonger
  • 12,554
  • 1
  • 18
  • 44
  • See https://diy.stackexchange.com/a/190844/18078 regarding pipe threads and making things come out a particular direction. However, there does seem to be a union in play here as @Tetsujin answers. – Ecnerwal Mar 12 '23 at 13:51
  • Also this one, even about gauges, specifically: https://diy.stackexchange.com/a/207107/18078 – Ecnerwal Mar 12 '23 at 14:00

3 Answers3

15

Are you actually having to twiddle the gauge onto the thread, hoping that by the time it's tight it will be facing the right way? That just sounds all wrong. You ought to be able to hold the gauge steady until the thread is almost tight, then twist it back approximating the last few degrees it will spin as the nut nips up. [Sometimes a little trial & error for a perfect result.] The thread otherwise always not only starts, but will tighten up in the same place. This not a sensible manufacturing method for something that must face an unknown yet specific direction.

This nut must be able to tighten independently of the gauge's orientation. You should be able to hold the gauge approximately stationary as you tighten up this nut.

enter image description here

Tetsujin
  • 7,716
  • 1
  • 16
  • 32
  • I can spin that part but then the gauge is on the other side facing the drywall. – Fresh Codemonger Mar 12 '23 at 16:56
  • 3
    The gauge should not spin with that nut. You should be able to hold it still. Can you imagine the same tightening up a U-bend on a sink waste - having to spin the entire U-bend round & round & hoping it ends up pointing exactly at your P-trap when tight? That way madness lies ;) – Tetsujin Mar 12 '23 at 17:01
  • I'll see if can spin the gauge to right side up independent of the threading - it might spin. The circled nut will not be involved. It is tight and the shutoff is in the correct orientation. The only thing out of wack is the temperature gauge. – Fresh Codemonger Mar 12 '23 at 17:05
  • 1
    If the large nut is hard-synced to the gauge barrel, then the next nut in to the left is going to be the one. It has to be this way, or gauges would just never line up… spinning u-bends again. No-one would ever make one that way. – Tetsujin Mar 12 '23 at 17:13
  • 5
    The thermowell spun without changing the threads. Thanks for the help! – Fresh Codemonger Mar 13 '23 at 02:41
  • @Tetsujin: Madness, definitely. And yet, I have encountered products like that... – psmears Mar 13 '23 at 15:30
3

If the female and male threads are not adjustable (the cutting method has been explained, but I don’t like that) then I use ptfe and tighten until it is both sufficiently tight and positioned correctly.

Or, since all you need is to notice a difference between the actual reading and what is required you can put a mark on the gauge glass.

Solar Mike
  • 24,863
  • 2
  • 28
  • 57
2

A pressure gauge can't use a thermowell, so the things with thermowells are just thermometers. In that case, the threads from thermometer to thermowell just keep the thermometer from falling out, and don't even need to be tight, as the fluid seal is made by the thermowell and its o-ring in its hole.

Ecnerwal
  • 174,759
  • 9
  • 212
  • 440
  • 2
    As usual, you don't pay attention: "The only piece I am looking to change the orientation of is the temperature well. It does seem to have two nuts on the back so hopefully it does spin independently of the thread orientation." – Ecnerwal Mar 12 '23 at 22:10
  • There were two different things. The first was the orbit pressure gauge on a hose bib. I rotated the 1/2" hose bib so that would face up. Seems like unless I only did it half tight it would have been out of position with the threads. The second piece was the thermometer / thermowell which I have the picture of... maybe I needed two questions. Thanks for the help. – Fresh Codemonger Mar 13 '23 at 02:42