I have some quick questions regarding installation.
I am going to install new check valve seals. What torque do I use for the pipe union fittings? I have seen 18 ft lbs. on this site. I looked in the BBB torque chart and for a 280, it shows to be 3.0 KPM (21.7 ft. lbs.). I have also read in Hayne's that you should 1st torque to 29 ft. lbs, back off and then tighten to 25 ft. lbs. Strangely, the BBB (07-13/2) has the proceedure listed and says the same as Hayne's. Why is the BBB proceedure torque spec different from the BBB Torque chart spec? Is it because it is a new seal versus installing an old seal? Which is the best torque?
According to the BBB, the injection pipe couplings should be 2.5 KPM (18 ft. lbs.). The pipe couplings of course should be less torque than the check valve union fittings.
And finally, when I unscrewed the check valve unions, some didn't unscrew easily by hand. When looking at them, it appears that they had some form of thread sealer on the threads. Is this necessary? I would think the seals below would take care of that.
Thanks for the help!