Connect 1/4" NPT to standard supply shut-off

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TorontoTim

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For my off grid cabin, I'd like to plumb in a water pressure gauge in the cabin to display the current pressure in the system, so I know roughly when it's time to run the lake water intake pump to fill my pressure tanks. Would be nice to know before jumping in the shower that I'm going to run out of water.

Anyhow - I have this nice old 1945 Sea Water pressure gauge that has what appears to be a 1/4" NPT tapered fitting that I'd like to mount in the bathroom I'm just finishing up.

It seems there are adapters out there to take it from 1/4" NPT to something else, but I want to make sure I get the right one. I've got a standard 3/8" Dahl miniball valve in the right location, so I'm looking for an NPT -> ? adapter so I can then mate the gauge and the supply valve with a standard braided line like I would a faucet.
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Reach4

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Impressive gauge. That might be a bronze nipple.

Compressed air often uses 1/4 NPT. You may be able to find some fittings in the section of the store that has compressed air fittings.
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I think you want a Brass 3/8 in. x 1/4 in. Reducer. Or did I get that backwards?
 

TorontoTim

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Need a 1/4 NPT Female on one end, and 3/8 straight thread on the other side or some other size that I can get a braided fitting for.

Looks like pneumatics etc. are one source - I just want to be sure I'm speaking the right thread language.

And yes, it would appear to be bronze.

At the end of the day it can be decorative, but it sure would be neat to have it on the wall plumbed in. I can leave a large enough hole behind it to access the valve so I can detach it and drain the system in the winter.
 

hj

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A 3/8 compression thread and a 3/8 pipe thread are two COMPLETELY different things and are NOT compatible. A 3/8 compression "Add-A-Tee" on the angle stop with a 3/8 x 3/8 braided supply line then a 1/4" female x 3/8 compression adapter screwed to it with the gauge into the 1/4" female opening will work. How are you pressurizing the tank, because the pressure could be zero even though you have a lot of water remaining in the tanks. What is that gauge measuring, because a "sea water" gauge would usually measure water depth, such as for a submarine. Sea Water, or Fresh Water is immaterial to a system pressurized by a pump.
 

TorontoTim

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The gauge is really just for fun. It's going in the bath at my off grid cabin. I pump water out of the lake into pressure tanks with a simple 120v jet water pump. Shutoff is around 50psi and it cuts back in at 30, if I happen to have electricity at that moment.

Since planning the bath I've added a 4000w inverter and a pile of 6v forklift batteries. Solar panels are going on the roof this week. So its not as important any longer to know if we're going to run out of pressure before jumping in the shower.

But if I can hook it up and it indicates something, then its still an interesting thing to have on the wall. I assumed it was measuring PSI but of course I don't even know if it works until I connect it to something.
 

Gary Swart

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Home Depot, and I'm sure there are other places as well, has a gazillion adapter and other fittings for these kind of connections. Take what you have and I'm sure you can make the connection.
 

hj

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quote; I assumed it was measuring PSI

As I mentioned previously, PSI has absolutely no bearing on whether it is "sea" or "fresh" water, but a submarine DOES have to know which it is and a gauge like that would give its depth below the ocean's surface, and long as it did not go too deep.
 

TorontoTim

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Went up to a friend's place to work on some motorcycles last night, and on a hunch brought my NPT fittings. He's in the fork lift business, and had a bin of bits that were destined for the trash at work. Loads of tapered thread fittings which convert to straight threads. Found a variety that thread into my gauge and have straight female and male threads on the opposite side, one or more of which will surely mate up with a braided supply line.

So off to the big box store to test fit some braided lines.
 

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Reach4

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Good. Note that water pressure falls off with gauge height at 0.434PSI per foot.
 

TorontoTim

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Well like I say, this is mostly for fun. Doesn't need to be all that accurate.

It will be handy from time to time, as being off grid, timing of electrical use is important even with the solar panels, a 4000w inverter and 12 x 6v 200ah batteries holding power. But originally this was planned before I had any of that, and had to run a gas generator every time I needed to fill the pressure tanks. So as I said before, having an idea that I might run out of water in the middle of a shower before getting into it was a nice thought.

I had a chance to test the gauge today. Oddly I found exactly the fitting I needed at Home Depot. A 1/4 MIP - 3/8 compression brass fitting. Removing the nut and little compression fitting left me with the 3/8" straight thread I needed just like you'd find on a typical supply valve.

Took a couple trips to find a 3/8 comp - 3/8 comp braided supply line, but I did find one and put it on one of the supplies here at home. It popped up to about 52 on the gauge and stayed put with no leaks or drama. So I'm assuming it's measuring PSI even though it isn't indicated anywhere on the gauge.
 
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