Alexander sorry about the leaks - many of us have been there. I have used these push in fittings for years on counter flow and plate chillers with excellent success. Leaking needs some tweaking. I’m assuming the leaks are around BPT threads only? Do not use gasket or o-ring here it’ll leak more. You may need another wrap or two of Teflon tape. It’ll tighten with more force required so don’t over tighten. Run water through it at steady flow and slowly tighten until it stops. I had to do this a few times after periodic cleaning but never an issue. Let us know if that doesn’t solve the problem.

The H928 and H920 o-rings are probably your safest bet. A couple metal washers on the duotight side can help take up any extra space and evenly distribute pressure around the o-rings.

Mine fittings all have attachments so I cannot measure them but I have them connected to Stainless Steel Quick Disconnect - Male QD x 1/2 in. FPT with no problems.

They are standard 1/2" BSP and compatible with 1/2" NPT. Thread diameter per specifications is 0.825 inch.

I get 0.8 inches measured with a micrometer.

Hi Colin we can't measure the threads with enough precision to give you a detailed answer however this is a 1/2'' BSPP fitting which would be designed to fit other 1/2'' BSPP fittings.