SuperPro O-Ring for Flo-Master, O-257-9

This is the SuperPro O-257-9 o-ring for Aqua-Flo Flo-Master pumps. It measures 4-3/4 inches on the inside diameter with a 3/32 inch cross section, and the source listing identifies it as the volute to bracket seal.

Getting the right ring

O-rings are easy to guess wrong at. The two numbers that matter are the inside diameter and the cross section, and both are printed above, so an old ring can be measured and matched before you order. This one is also carried under the substitute numbers 5000-2626 and 90-423-5158, which is worth knowing if your parts list uses a different catalog.

Fitting

Clean the groove, check the sealing face for scoring, and give the new ring a light coat of silicone lubricant so it seats evenly as the housing pulls together. Once an o-ring has taken a set it will not reseal the same way twice, so fit a fresh one whenever the wet end has been apart.