Plumbing question, are there any other options besides NPT?

F&S reef · Apr 22, 2023

I'm working on my plumbing on a new tank and I'm trying to do a lot in a small area. I have purchased the newly released 1" flow sensor for Hydros which coincidentally looks identical to the Apex version except rebranded and with a different plug. Both units come with unions to attach them to 1" plumbing. My issue is I am already attaching this to a union so there is zero need to attach a union to a union. My plan was to just direct thread the flow sensor into my existing 1" union but guess my surprise when I got it and tried to do this and discovered that the threads on the sensor are straight and not NPT. The sensor will thread onto the supplied unions perfectly but no other standard NPT unions. I need to keep this section as short as possible so I am looking for a way to make this work. I can not just sub in the supplied unions as where I want to attach it is a proprietary union that belongs to another piece of equipment.

Long and short of all that is anyone aware of plumbing parts that are just straight normal thread and not tapered pipe thread?

Saltyreef · Apr 22, 2023

A lot of aquarium threaded plumbing parts from overseas ive encountered use british pipe thread.
Most straight threads wont seal without the use of tape.

Is it possible you are encountering a BSPT but trying to thread NPT into it?

Am i understanding correctly that you want to install this between your exisiting unions that are proprietary to another piece of equipment?

Maybe some photos will help me figure out an adapter or something.

I assume the compatability between union threads is different as well? Most times they are to negate something like half a spears and half a GF brand union fitting together.

F&S reef · Apr 22, 2023

Thank you for the reply, I measured the major diameter of the threads and it doesn't seem to be metric or standard. The closest TPI is a standard 11 teeth per inch and its very close but not 100% perfect. Also the major diameter of the threads is 1.287" or 32.7mm This doesn't fit anything I'm familiar with. The provided unions just thread on smoothly all the way down and do not seem to have any taper at all. Will 100% require help sealing.

I'm trying to plumb this flow sensor right off the output of a pentair 25w UV. I said "proprietary" earlier but that's not 100% accurate. Its a 1.5" slip union that threads to the UV and then you can reduce as needed. I have a spears 1.5" slip that has a 1" NPT threads on the inside. I want something that I can just thread this sensor into that will then have 1.5" slip on the OD of said part. Below is pics of what I have and where its going. I need to keep this as short as possible to reduce the bend radius the piece of hose coming off the sensor. If I knew what this thread was on the sensor I would order a 1.5" slip with as small of threaded ID as possible and machine it out and tap it for this thread if an off the shelf option wasn't available.

I would have though for sure with the sensor being near identical to the neptune version that someone has encountered this with as long as its been out but google is not producing any hits.

F&S reef · Apr 22, 2023

I just looked more and found this looking for info on the neptune sensors.

"Like many pumps and plumbing products meant for a global market, the flow sensors use British Standard Pipe (BSP) threads"

SO....... now im looking for BSP threaded plumbing parts that have standard sized features otherwise.

Saltyreef · Apr 22, 2023

I see now.

So i just looked up the part and on the front of the box it infact says BSPP which is british standard parallel pipe thread. (British straight)

I would look for a BSPP x 1.5" slip adapter.

Saltyreef · Apr 22, 2023

F&S reef said:
I just looked more and found this when looking for info on the neptune sensors.

"Like many pumps and plumbing products meant for a global market, the flow sensors use British Standard Pipe (BSP) threads"

Yep. Thats what i originally suspected.

Saltyreef · Apr 22, 2023

So i just noticed that the included unions are custom made 1" BSPP x 1" slip.
Use both unions and then use this reducer and a small 1" piece of pvc to join the union to your UV.

437211 PVC Reducer Bushing 1.5" Spigot x 1" Soc

Factory Original Spa & Hot Tub Parts, Tech Support and Lowest Prices

www.spapartsguy.com

I think its your only option shy of finding a 1" BSPP x 1.5" slip reducer to negate the supplied union.

Sorry! BSPP is very hard to come by and they likely dont make this adapter for general use.

ca1ore · Apr 22, 2023

Although you are stuck with the part of the union that threads onto the sensor and accompanying collar, you can replace the flange which will allow you to eliminate the extra union. The spare flanges that come with the 1” cepex true union ball valves will work. Sometimes the ID of the flow sensor collar needs a slight enlargement. Not sure if that helps or not.

Saltyreef · Apr 22, 2023

ca1ore said:
Although you are stuck with the part of the union that threads onto the sensor and accompanying collar, you can replace the flange which will allow you to eliminate the extra union. The spare flanges that come with the 1” cepex true union ball valves will work. Sometimes the ID of the flow sensor collar needs a slight enlargement. Not sure if that helps or not.

The way he has the union installed in this photo makes it look like the threaded side is the flange side. The opposite side is already a 1" slip.

I could be misunderstanding your recommendation though....
View attachment 3120290

ca1ore · Apr 22, 2023

Ah, maybe. On the Neptune flow meters it’s the other way around.

Saltyreef · Apr 22, 2023

ca1ore said:
Ah, maybe. On the Neptune flow meters it’s the other way around.

I noticed that too on the first photo lol.
I was confused for a quick second!

F&S reef · Apr 22, 2023

ca1ore said:
Ah, maybe. On the Neptune flow meters it’s the other way around.

Youre right, I just compared and the unions included are backwards from the ones included with the neptune version.

F&S reef · Apr 22, 2023

What would that exact size be with the dimensions that I provided? I am just going to machine and tap another slip joint to make this work. Not a problem for me nor the first time I ve done it so far for this setup. Its a waterbox and came with all metric plumbing. Ive already had to machine a part for another union to make it play nice with a standard fitting.

Saltyreef · Apr 22, 2023

Not sure how a new flange would negate the use of one of the unions....

Something is going to be needed to adapt BSPP to US. Those unions fit the bill.

Just use the spigot reducer adapter i linked between the union and your UV.

Saltyreef · Apr 22, 2023

F&S reef said:
What would that exact size be with the dimensions that I provided? I am just going to machine and tap another slip joint to make this work. Not a problem for me nor the first time I ve done it so far for this setup. Its a waterbox and came with all metric plumbing. Ive already had to machine a part for another union to make it play nice with a standard fitting.

So you need maybe a 3/4 thread on the adapter to tap a 1" bspp to it i would guess.
But have you found a 1" BSPP tap yet??

F&S reef · Apr 22, 2023

Saltyreef said:
So you need maybe a 3/4 thread on the adapter to tap a 1" bspp to it i would guess.
But have you found a 1" BSPP tap yet??

Thats exactly what I'm going to do, I'm going to get a 1.5" x 3/4" double slip and then machine and tap the ID for 1" x 11 BSPP.

I just started looking for the taps, found one on amazon for $45. Im going to try to find cheaper as its just cutting PVC. Otherwise as I like to say when spending too much for something..... Ive spent more on less.

F&S reef · Apr 22, 2023

Saltyreef said:
I see now.

So i just looked up the part and on the front of the box it infact says BSPP which is british standard parallel pipe thread. (British straight)

I would look for a BSPP x 1.5" slip adapter.

lol, I see that now. I just went and grabbed the box and bam there it is right on the front. I would have never expected that info to be right there.

Saltyreef · Apr 22, 2023

F&S reef said:
lol, I see that now. I just went and grabbed the box and bam there it is right on the front. I would have never expected that info to be right there.

Yeah i was thinking, if they supplied the threaded unions for it, its likely a special thread.

iirc, Jebao return pump discharge threads are BSP too.

I hope you can get by with my suggestion and use that 1" slip x 1.5" spigot i linked and its not too long.

Maybe you can find a spigot 90 for the other side so it stays as short as possible for turning into your cabinet.