Screwfix ball valve

john998

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VOC Member
Hello Trevor,
Quite right, one thread different, NPT is 18 tpi BSP 19 tpi. It is in my mind that i used to interchange them at work, perhaps I am thinking of 1/2" John
 

Tom Gaynor

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VOC Member
There's a foot of snow outside so I can't get out to the garage to look at the numbers on mine. That number looks familiar. If they come from Screwfix in the UK, they're PROBABLY BSP. I've bought eight of them in all. They're about $6 each and the first ones I bought four or five years ago are still perfect.
Most of the sites I looked at to find them don't list the threads, assuming perhaps that British plumbers KNOW that if it's a 6 mm ball valve they'll be BSP. Four of them had male (tank) threads that were BSPT (tapered). I ran a die down two of those, but discovered that I needn't have bothered. I use Loctite thread sealant - the tank connection on mine has no flange. Works fine, has done for 5 years.
 

john998

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Hello,
No more snow yet so have been briefly in the garage.
The Screwfix 8mm valve I have is 19tpi BSP. when I fitted one on the outfit I made up an adaptor, known in the trade as a gauge adaptor.
1/4 female to 1/4 male. This allowed me to use the olive that came with valve to seal a short piece if 1/4 pipe into the valve to increase the
amount of reserve on that side. another advantage is that you can make the male thread longer and use a 1/4 BSP nut so you can position
the tap more easily.
If you want to screw the tap in directly you will need to seal it with a good thread seal as there is no flange and the thread is parallel.
The mystery is why we are still using BSP in a metric world.

John.
 

Tom Gaynor

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VOC Member
The number for the BSP valves is the one quoted at the start of this thread.

My valves, let's call them taps, are the other way up from John's. I used a male x male crossover on the female, lower tap connection, and one end of the crossover accommodated a nipple. This meant that if I screwed the male end of the tap (mine was BSPT), sans flange, into the tank, I'd 1) be able to use my standard Vin fuel lines without modification, and 2) I'd need to seal the thread. Sheer serendipity: ball valve plus crossover is almost exactly the same length as a standard fuel tap. I used Loctite Thread Sealant, and it has worked perfectly over 4 or 5 years. AND I can take the taps out without wrecking the tank. (I haven't had to use heat, took 'em out cold, but it doesn't take much heat to soften Loctite anyway, boiling water will do it.

In a thread on the same topic, someone told me that he had managed to buy mini ball-valves which were male BSP (not BSPT) and flanged both ends. Maybe they are still out there.

Why metric? My guess would be that there are enough old cookers out there built with REAL threads, to provide a demand.

Tom
 
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