Replacing Drain cock ... can you change the angle a fitting locks up by grinding down the thread

[Submariner1]

I need to replace my existing drain valve, by using a 90 deg. Elbow and a nipple extension and a mini ball valve. With a hosetail to use some plastic tubing to collect the water.

And avoid getting down and grovelling around to reach the cock tap! ( a total pain) sandwiched between a Saw and a Mower.

The original cock also blasts air and water straight at the ground, which only has 20mm clearance, so effectively blasts wet air back up onto the bottom of the tank! ... a dumb way to rust the tank and the wheel chassis!

Its going to be crucial, that the final angle once the elbow is reasonably tight ( using Loctite 577 ) is pointing to the side of the tank ( to access it).

Apparently the tank has a 3/8 parallel female, and the original Cock valve has a 3/8 G fitting, which I assume is BSP P (parallel).

my question is:
If the street elbow (with a parallel nipple into the female end of the elbow) ends up pointing the wrong way once tightened;
Can one alter the angle it locks up by grinding off say 1/2 a thread turn on the nipple. So it effectively starts the thread engagement 1/2 a revolution earlier?
( I am hoping that works).
Note I have had Loctite 577 fail on one previous joint, when I had to back off the fitting 1/2 a revolution to get the angle right. Admittedly I did “bump” the joint accidentally, quite lightly, after about 5 mins ( so I might have disturbed it as it was setting off). As its awkward to get, at definitely I don’t want to risk a compromised joint.
Likewise:
Would the same idea work if I put the male BSPT end of the elbow into the tank?
I suspect that would not alter the angle the elbow ends up; because the tightening point is more determined by the position where the taper gets fat enough, (in the parallel female of the tank) to lock it up. Or is my logic on this concept flawed?

I am hoping the female on the tank, stops the nipple protruding into the tank, i.e. locks up before the nipple is higher in the tank, than the floor of the tank. Do most tank manufacturers think of this potential water trap? Or do I have to ensure (by measuring / counting the threads) that this does not happen? , and create a slight water trap in the tank.

 

[Seadog]

Use a setting thread sealant, such as the Screwfix PTFE. Adjust to where you want it to be and leave it to harden.

 

[Shox Dr]

Use a setting thread sealant, such as the Screwfix PTFE. Adjust to where you want it to be and leave it to harden.

Not used that. Loctite do Positional Setting sealant both PTFE and traditional liquid. Or the old way with either flax/hemp and Boss white or PTFE tape.

 

[Submariner1]

Use a setting thread sealant, such as the Screwfix PTFE. Adjust to where you want it to be and leave it to harden.

Thanks looks a good price too.
Does it really seal parallel threads wherever you position them? (Even though not tightened up )
And how long does one have to leave it to Totally set off? ( note dont mind if for perfection one has to leave it 72 hours, as long as its really sealed perfectly)

as you can see its a pig to get at and means putting the lawnmower in the drive, when one is working on the joint, obviously the mower can go back whilst its curing.

 

[Shox Dr]

Thanks looks a good price too.
Does it really seal parallel threads wherever you position them? (Even though not tightened up )
And how long does one have to leave it to Totally set off? ( note dont mind if for perfection one has to leave it 72 hours, as long as its really sealed perfectly)

Within reason. You should get it as tight as you can, if necessary back off.

 

[mike os]

liquid hydraulic positional sealant or a positional fitting...... basically an elbow with a locknut

 

[Wildefalcon]

Combination of PTFE tape and PTFE liquid will do exactly what you want, the tape gives the seal body, and the liquid allows the position. Do let it set, though.

 

[Mikes]

If the M&F elbow (what you call a street elbow) has a parallel thread on it then just use a backnut with it which will then let you tighten it in the direction that you want. if you are doing this then as setting compound as Seadog's recommendation is probably best. Obviously no good if the elbow has taper threads in which case just use plenty of ptfe tape. It might take a couple of attempts to see where it wants to stop but usually can get up to 180 degree more movement from when it first gets tight enough to seal. Pipe fitters have to do this every day.

 

[RonA]

Following a suggestion by somebody on the forum (sorry cant remember who) I bought one of these & took the auto drain off the bottom. Then managed to fit it in a pipefitting screwed to the drain on the air reservoir, The valve is open when starting up & closes at about 10 psig. After the compressor is stopped it reopens when pressure falls back again to 10 psi. If you need to drain at pressure you just push the bottom of the drain up slightly.Reduces the need to get down on all fours to open the drain & not expensive.
https://www.machinemart.co.uk/p/clarke-cat152-14-mini-air-filter/
RonA

 

[Wildefalcon]

I use an auto drain, works well.

 

[waddycall]

Put the Street elbow into the compressor - Wind about 12 wraps of ptfe around the thread. Pull the tape tight as you wrap it round then run your fingers over it in a clockwise direction to smooth it out. Tighten it up until it’s getting tight and then stop winding it in when it’s in the right position.
I wouldn’t use any parallel fittings on there unless they have a flange to seal against. The nipple in the picture doesn’t.

 

[captain-destructo]

As its already been said plenty of ptfe tape, boss white, or locktight sealant
tighten it to the position you want dont back it off once tightened

possibly make a bracket so it doesn't get moved when being used and therefore breaking the seal
I wouldn't worry about the threads poking up into the tank. The pipe that the elbow screws into probably already does that already


but more importantly that is not the correct use of a hockey puck!!!

 

[Turbo]

I have made a similar mod to my compressor, running the pipe out through the wall so that the water/oil mix goes outside! I used loctite 577 & if you tighten the joint up tight then let it set overnight it will not budge! The other option is to use green loctite, once it sets you need heat to release it!

 

[Bullet2012]

This is the great thing about this forum, someone asked a question that may seem to have a simple answer. The members then all chip in offering good sound advice, no disrespectful replies, just good helpful advice.
Well done Forum another great job. Have a hug and please continue to help us that ask questions that may seem simple to some but can be difficult to the brain of the person asking. .

 

[julianf]

Use a taper on the male.

Personally I'd get one of these -

https://www.bes.co.uk/compression-straight-adaptor-15mm-x-3-8-bsp-tm-24557/

And go to a 15mm copper with whatever bends and valves that you like on it.

But in answer to your original question, it will be the last bit of thread by the collar that determines the final rotation. You could have the thread as 10mm or 1000mm and it will just keep turning until it locks up on the collar when using a parallel male.

 

[Submariner1]

As its already been said plenty of ptfe tape, boss white, or locktight sealant
tighten it to the position you want dont back it off once tightened

possibly make a bracket so it doesn't get moved when being used and therefore breaking the seal
I wouldn't worry about the threads poking up into the tank. The pipe that the elbow screws into probably already does that already


but more importantly that is not the correct use of a hockey puck!!!

thanks and yes agreed on the hockey puck, just needed something to improve the ground clearance - before these it was a total mare lying down to get at the drain lever!

 

[Submariner1]

I have made a similar mod to my compressor, running the pipe out through the wall so that the water/oil mix goes outside! I used loctite 577 & if you tighten the joint up tight then let it set overnight it will not budge! The other option is to use green loctite, once it sets you need heat to release it!

I have made a similar mod to my compressor, running the pipe out through the wall so that the water/oil mix goes outside! I used loctite 577 & if you tighten the joint up tight then let it set overnight it will not budge! The other option is to use green loctite, once it sets you need heat to release it!

Loctite technical came back to me and said 577 was the way to go, and my one issue when I had to back off 1/2 a revolution, was because it was a BSPT male into a BSPP female ... too much play on those fittings - allowing an airway.
Says he is sure 2 BSPP fitting will be perfect after 24 hours.

 

[Submariner1]

Following a suggestion by somebody on the forum (sorry cant remember who) I bought one of these & took the auto drain off the bottom. Then managed to fit it in a pipefitting screwed to the drain on the air reservoir, The valve is open when starting up & closes at about 10 psig. After the compressor is stopped it reopens when pressure falls back again to 10 psi. If you need to drain at pressure you just push the bottom of the drain up slightly.Reduces the need to get down on all fours to open the drain & not expensive.
https://www.machinemart.co.uk/p/clarke-cat152-14-mini-air-filter/
RonA

Hi
I have a similar 1/2” PCL one, but that drains the filtered air, not the tank.

 

[Submariner1]

I use an auto drain, works well.
View attachment 268130

thats the long term plan, but pushed the budget to buy a belt driven compressor.
And the ones I saw were all circa £130 ish.

 

[Submariner1]

Put the Street elbow into the compressor - Wind about 12 wraps of ptfe around the thread. Pull the tape tight as you wrap it round then run your fingers over it in a clockwise direction to smooth it out. Tighten it up until it’s getting tight and then stop winding it in when it’s in the right position.
I wouldn’t use any parallel fittings on there unless they have a flange to seal against. The nipple in the picture doesn’t.

thanks,
Very cute little kitty you have there ... make every moment count
Sadly, lost my darling little workmate (despite £7000 on Chemo) in December
So a crap Xmas.