Connecting circulators with flanges

[Joebin]

A quick simple question please: When installing a small circulator with flanges- do you compress the O-ring until the flanges touch? It feels like the O-ring will split if I do this. If not - how to you determine torque amount on your flange bolts?

Thanks.

 

[ewdudley]

Just tighten evenly on both sides until flanges are perfectly parallel and touching the gasket, then another three or four quarter-turn swings of the wrench on each side. You may end up with very little gap between the flanges or you may have 30 thousandths or more depending on the particular flanges, gaskets, and pump. You shouldn't need much more torque than can be applied with a thumb and two fingers on the wrench two or three inches away from the nut.

I suspect it would be pretty easy to bust off the ears of a flange if you got carried away.