Identifying the size of a water meter / correct meter coupling

[klm917]

Hi all,

I want to replace the old pipes directly after my water meter as part of a larger re-piping job, and one of the things I need to do is replace this old water meter coupling. I have had a hard time identifying the proper size and finding the proper coupling. I am sure that the male end of the coupling is 1/2" NPT because I carefully measured the circumference and compared to other 1/2" NPT items. You can't see in this picture but immediately after the male end it is attached to an upsizing coupling which converts it to 3/4".

I went to a plumbing supply house and the guy sold me a 1/2" meter coupling, but after bringing it home and looking at it next to the current one, I think the female end (the union that connects to the meter itself) is too small.

The meter itself says 5/8" but I didn't see any 5/8" x 1/2" couplings online, perhaps I can upsize it to this 5/8" x 3/4" version? I am going up to 3/4" after the meter anyways so that would be good. Looking around on the internet, 5/8" meter couplings don't even seem to be widely available. I could try to save the existing one but it looks rusty and i'm sure it will need a new gasket anyways.

I tried looking at Neptune's website as well and the different sizes are pretty confusing.

I can post further pics later if needed, including of the new meter coupling I purchased... Your expertise is appreciated!

 

[wwhitney]

Per the site below and a bit of inference on my part, 1/2" AWWA meter threads are 3/4" NPSM and have an OD of 1.04"; 3/4" AWWA meter threads are 1" NPSM and have an OD of 1.39"; and 1" AWWA meter threads are 1-1/4" NPSM and have an OD of 1.65". So you can measure the OD of the exposed threads to determine what you have.

Also in case you are not aware, since these are straight threads, the threads are not a sealing surface and you should not use any thread sealant on them. Instead, the female fitting needs to have a rubber washer inside that the end of the male fitting compresses against.

USA Water Meter Sizing FAQ

Water Meter specifications in the USA are controlled by the American Water Works Association (AWWA). If you are new to the waterworks or metering industry, meter and meter connection sizing can be confusing. Following is information to help you determine the correct size meter or couplings you...

utility-technologies.myshopify.com

Cheers, Wayne

 

[Sponsor]

 

[klm917]

Thanks for your response. I cut a piece of string that exactly fits around the threads and it's just about 3 3/4" circumference. If I divide that by pi, which is I think the way you do this, I get an O.D. of around 1.2, which is right in the middle of the two sizes you sent. I think the guy at the supply house sold me the 1/2" AWWA (1.04" O.D. version) but I think the 3/4" AWWA will be too big. I might actually need a 5/8" size, which seems to disagree with the below (from the link you posted)

5/8" WATER METER (ALSO REFERRED TO AS 5/8" X 1/2")​

A 5/8" water meter has a 5/8" water flow capacity. The bore of the meter is generally 5/8". a 5/8" meter does not have 5/8" threads. It has 1/2" AWWA Meter Threads and typically hooks up to a 1/2" or smaller water service line. A standard meter coupling for a 5/8" water meter has male NPT pipe threads on one end and a swivel meter coupling nut with 1/2" AWWA Meter Threads on the other. These use meter couplings and gaskets referred to interchangeably as 5/8" or 1/2". 5/8" meters are generally used on older homes where the service tubing size was 1/2"

Also, my main water service is 3/4" and it goes through a reducing coupling before the meter, and then sizes back up to 3/4" after the meter

 

[wwhitney]

Well, you've exhausted my knowledge on the topic. Why do you need to replace the meter nipple?

The other suggestion I have is to measure across the flats of the hex nut on the existing meter nipple, and then at the supply house check that measurement against your various options. Along with measuring the apparent ID of the female end. Since you resorted to the string technique, sounds like you don't own any calipers; this project would be a good excuse to buy an inexpensive pair.

Cheers, Wayne

 

[klm917]

A.Y. McDonald 5/8 x 3/4 in. Swivel Nut x MPT Brass Reducing Meter Coupling - 5124-065 - Ferguson

5/8 x 3/4 in. Swivel Nut x MPT Brass Reducing Meter Coupling (5124-065) at Ferguson. Nobody expects more from us than we do. ®

www.ferguson.com

I think I might need this size but it seems to be out of stock everywhere...

 

[klm917]

Well, you've exhausted my knowledge on the topic. Why do you need to replace the meter nipple?

The other suggestion I have is to measure across the flats of the hex nut on the existing meter nipple, and then at the supply house check that measurement against your various options. Along with measuring the apparent ID of the female end. Since you resorted to the string technique, sounds like you don't own any calipers; this project would be a good excuse to buy an inexpensive pair.

Cheers, Wayne

Thanks, I'll see what I can figure out. I assumed I should replace it because the threads look kind of rusty on the NPT end, but I can probably figure out a way to use what's already there, as long as the threads seal well.

 

[wwhitney]

I suggest checking if it's brass or iron (scratch or file the body, or check with a magnet), I would expect brass. If it is iron, then do replace it.

But if it's brass, all you are seeing at the end is dried up thread sealant. When changing out the downstream connection, you should be able to remove it all without damaging the threads. E.g. with some water, a stiff nylon or brass brush, and some elbow grease.

No real upside to trying to get a water meter nipple with a 3/4" NPT end, while the greater ID for 6" would give you slightly less pressure drop under flow, I expect it would be on the order of 0.1 psi.

Cheers, Wayne

 

[klm917]

A.Y. McDonald 5/8 x 3/4 in. Swivel Nut x MPT Brass Reducing Meter Coupling - 5124-065 - Pollardwater

Shop for 5/8 x 3/4 in. Swivel Nut x MPT Brass Reducing Meter Coupling (5124-065) at Pollardwater.

www.pollardwater.com

I did find it here at "PollardWater" which seems to be a subsidiary of Ferguson, I just bought it for $23 so hopefully that is the correct size. If not, I will still try to preserve the old one.

 

[klm917]

I suggest checking if it's brass or iron (scratch or file the body, or check with a magnet), I would expect brass. If it is iron, then do replace it.

But if it's brass, all you are seeing at the end is dried up thread sealant. When changing out the downstream connection, you should be able to remove it all without damaging the threads. E.g. with some water, a stiff nylon or brass brush, and some elbow grease.

No real upside to trying to get a water meter nipple with a 3/4" NPT end, while the greater ID for 6" would give you slightly less pressure drop under flow, I expect it would be on the order of 0.1 psi.

Cheers, Wayne

Thanks, I will do that. I actually suspect it might be iron, it is quite black, but I will test it later. It is connected to very old galvanized steel, which I will be replacing. (the purpose of the project). It's a 100+ year old house I moved into last year.

 

[klm917]

Well, I spoke to the guy at the city in charge of water meters, he said he recommends reusing the old one. He said even if it’s black it is likely and older brass (superior to the new brass). He said it is 5/8” and if it did need replaced, the city would be able to source one. He noted it is a less common size.

Pollard Water also called and noted the item I ordered is on back order so definitely hard to find…