How to seal a female coupler?

Hey everyone, the coupler is being screwed onto one side of a standard right angled compression elbow (only without the nut and olive on that side).

It's just a standard thread like you'd have on any other compression fitting so I dont think tapered.

The little disagreement you guys are having is exactly why I'm asking this question, is PTFE enough for a water tight seal or am I supposed to use a rubber washer or something? Are you supposed to use a rubber washer beyond hand tightened fittings?

Cheers.

Wrong fitting for the job of your screwing onto a compression elbow

OP:

PenguinWithHair said:

Apologies for what's probably a very basic question, but I've just bought a female straight coupler, which has a normal compression fitting on one side, and the other side screws onto a thread.

The normal part is fine, compresses an olive. But the 'female' side doesn't have an olive, it just screws onto a half inch thread. What makes the water tight seal here? There's no olive or rubber washer, just two threads.

Many thanks.

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OP: You have a compression elbow. That will be a parallel thread. The female will be parallel (all female threads are). Therefore you will need a washer. It is obviously important that the male grounds on the washer.
The only problem is that the end of the male is not flat, but has a taper. This can damage the washer. But the combination is used quite often, although not strictly correct.

PenguinWithHair said:

The part is for fitting a replacement electric shower, I've got a threaded elbow sticking out the wall which my old shower fitted nicely onto but not my new one. I'm using this coupler for a mini extension of that elbow and it's a perfect fit.

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@PenguinWithHair what you’re doing is a bit of a bodge, but we’ve all had to adapt and overcome at some point .
Ideally, you’d move the shower or move the pipe.
It’s likely that the female lip will hit the inside angle of the elbow before the male thread is fully home inside the female socket so you’ll have to try a stack of washers... fibre ones would be better as they swell to seal. Also wrap loctite ptfe string around the male thread. Get yourself a compression cap so you can test watertightnes before mounting the shower.

Might also be worth filing the end of the male thread so it has a bit of a “flat” rather than sharp edge.

https://www.screwfix.com/p/arctic-products-flexible-tap-connector-washers-10-pack/2035j

http://www.loctite.co.uk/pipe-sealing-9886.htm

https://www.screwfix.com/p/15mm/55441

PenguinWithHair said:

Apologies for what's probably a very basic question, but I've just bought a female straight coupler, which has a normal compression fitting on one side, and the other side screws onto a thread.

The normal part is fine, compresses an olive. But the 'female' side doesn't have an olive, it just screws onto a half inch thread. What makes the water tight seal here? There's no olive or rubber washer, just two threads.

Many thanks.

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From this and later posts, it sounds like you have a male thread, presumably 1/2"BSP taper, sticking out out of the wall, and you want the same male thread, but about 30mm further out. So I assume you will discard the compression nut and olive. Or is it a compression joint on the new shower?
The male thread on your new fitting is parallel (as you said in one post), have you tried it in the new shower? According to attached data, if the shower is taper it doesn't work, though in practice it might be OK, sealing it with paste (I use Stag) or PTFE tape. If it's parallel, you could use paste/tape, or preferably, as somebody said, you might be able to use a fibre washer, if the end of the fitting has a flat part in addition to the olive taper. If not, you could carefully file it to give a flat.

Similar options on the other end. I would guess the female end of your fitting is taper thread, so it's paste/tape. If it's parallel and you want to use a washer, there would have to be a flat surface inside the fitting.

As an aside, modern 15mm compression fittings use 1/2"BSP threads, but I have some old ones with finer thread. Obviously as you have both parts it doesn't matter. I also have 22mm compression fittings with different threads. Neither is 3/4"BSP as there is insufficient wall thickness for a 3/4"BSP thread when 22mm is subtracted from the OD of a 3/4"NB pipe.

PenguinWithHair said:

The little disagreement you guys are having is exactly why I'm asking this question,

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Post some photos,at the mo your getting scatter gun replies. if you have not got the ability to post photos here forget about plumbing in mains electric shower & water. safety first aye

Yea ok, thanks for all the replies everyone.

PenguinWithHair said:

Yea ok, thanks for all the replies everyone.

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My reply was not “scatter gun”!
You have a plastic inlet tube on the shower that needs a pushfit or compression connection to the cold main supply and this is no longer in reach because you have a different unit to the original and need an appendage?!

As , I said above... moving shower or supply is the usual procedure.

Else it’s A&O.