What Vacuum valve for 16mm unthreaded hole

What would the best vacuum valve be for a 16mm unthreaded hole.

It will need

A seal on the outside that is clamped on between the valve and outer housing

Needs about 15mm of thread to protrude through the housing

Needs a jam nut

Preferably would have a gauge on the hand pump

Thanks for the help

Most of the ones I have seen have a rather short thread designed to thread into the housing.  A solution might be to have a bush machined up that fits the hole complete with either o-ring or gasket  secured by a nut inside, and thread it on the inside to accept one of the available valves there are m14 valves and 1/2"-20 (1/2"UNF) threaded valves available. 

The clearance drill for M14 is 14.29mm and 1/2- 20 is 13.1mm giving a wall thickness of 0.85mm and 1.45mm respectively after tapping.  You would have to consider how to design the gasket for the bushing - I assume there is sufficient flat surface around this hole to allow a seal to be established. 

Thanks Chris

Appreciate the considerations. I think I could make most brands of valves work with a trip to Pirtek, but I was hoping something may be available off the shelf.

This unit from Mangrove looks like a possibility. Not sure of the quality though  https://www.aditech-uw.com/en/shop/4396-mangrove-m14-vacuum-valve-pld-m14.html

The concern with using that would getting the gasket right, you'd have a 0.85mm gap all round the M14 threaded part that the o-ring would be straddling.  You would need to have that part centred in the hole and knocking it off centre might break the seal?

Is this in a housing?  I would not have thought an un-threaded 16mm hole would be that common in a housing.

Yep aquatech surf housing

Might be best to get a M16 and enlarge the hole if required.

3 hours ago, Chris Kippax said:

Yep aquatech surf housing

Might be best to get a M16 and enlarge the hole if required.

M16 clearance drill is 41/64" = 16.27mm.  You could also run an M16 tap through the hole - the thread would not be strong enough to trust to hold it in place, you would need an M16 nut inside I would think.  I assume the housing outer surface is smooth to seat the o-ring.

Not sure if anyone is interested but I just tapped a 3/8 Unf  thread in the top of the housing and mounted an Ikelite 3/8 vacuum valve, seemed to be the most robust way to do it with adding minimal failure points. Tested it today, held 5 in/hg for 24 hours and survived a swim in the pool.