valve questions

[LAP57]

Found this thread while I was looking for info on attaching an SPG to a tank valve. I have two tanks with Dacor J-valves and HP ports. The valves had black plastic on the nobs and on the j-valves. What size threads are these most likely to require?

[captain]

Most likely 3/8", same as on most regulators of the time.

[LAP57]

About what year did the industry shift to 7/16 for hp ports?

[captain]

No idea but probably in the 90's. My newest regulator is a 1884 Scubapro MK V and it is 3/8"

[YankDownUnder]

Adapters are available to convert early 3/8" HP to the new 7/16th" HP thread if you want to use late hoses. The tank valves are down stream, so the gauge is off when the air is off. It's a good alternative to the banjo fitting, but you will be doing a lot of wrench work if you do not have a gauge per tank. The banjo is cheaper in that way.

You may not come across it, but some very early double tanks have a manifold plug which is stamped "Do Not Remove". These are for up stream gauges. Don't remove them with air in the tank. Steve

[LAP57]

I do have a Dacor double manifold that I may be putting back into service and it has a HP port. I will be carefull if I decide to put a gauge on it.

Good info, thanks.