Pentair Washer 5/16″ ID x 3/4″ OD, 72173

Pentair 72173 is a stainless steel flat washer measuring 5/16 inch inside diameter by 3/4 inch outside diameter. It is generic looking hardware that appears on a surprising number of parts diagrams, from Challenger pumps through PacFab Nautilus DE filters to the Purex CFM, CFW, 2000 Series and 4000 Series filter families.

What it does

A flat washer spreads the clamping force of a nut or bolt head over a wider area. On filter clamps and pump hardware that matters, because without it the fastener bites straight into the casting or the band and slowly deforms it. It also gives the fastener a clean, flat face to turn against so torque readings mean something.

Ordering

The source parts listing shows this washer as four required. That number belongs to a particular assembly, so count the washers you removed and work from your own diagram rather than assuming. Renew all of them together while the assembly is apart, since a corroded or dished washer will not clamp evenly against fresh ones.