We've had a lot of sediment in the water after this past month's flooding. Water pressure also jumped to 100psi. The Water Authority had to shut down a plant and reroute the system through some disused conduits. So I bought an overpressure valve, a little spin-down filter, and a two-stage point-of-entry filtration device and am now working through what fittings will best enable individual components to be removed and serviced.
The plumbing in the house is 3/4" copper. The spin-down filter has multiple ways to connect. It has 1" MNPT threads. Inside each of those threads is a 3/4" FNPT thread. There is also a threaded coupling option that fits over the 1" male thread; it has a 3/4 MNPT brass fitting that emerges from the coupling's hex nut; those 3/4 MNPT brass fittings would protrude on either side of the filter like ears. Inside the coupling's hex nut the seal is made with a flexible washer.
The 3/4 MNPT brass fitting has no wrench flats (see picture) but there are two little tabs inside it. I assume those tabs are meant to be used with a key wrench of some kind, to let you tighten a 3/4 FNPT fitting onto the brass fitting? If that's right, is there a name for that kind of key wrench?
Best Answer
To unscrew that fitting with the inside knobs or as you said "tabs", try using a "spud wrench" which is a tool used by HVAC people to replace union fittings on cast iron radiators. Your local HVAC company may have one you could borrow for a few minutes.