Pentair 357255Z strainer cover o-ring, Buna-N 70, size 2-357Pentair Strainer Cover O-Ring, Buna-N 70, #2-357, 357255Z In stock$999
Pentair 357255Z strainer cover o-ring, Buna-N 70, size 2-357
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Pentair Strainer Cover O-Ring, Buna-N 70, #2-357, 357255Z

Ask a questionMPN 357255Z
$999
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Quick overview

  • Genuine Pentair Part 357255Z, the factory strainer cover o-ring.
  • Buna-N 70 durometer The material and hardness Pentair specifies for this seal.
  • Size #2-357 The standard AS568 dash size, so the cross section and diameter are exact rather than close.
  • Seals the pump lid This is the o-ring that keeps the strainer pot airtight so the pump can hold prime.
  • A common prime problem A hardened or flattened lid o-ring lets air in, and the pump loses prime or runs with air in the basket.
  • Cheap insurance The o-ring is the first thing to change before chasing a suction air leak anywhere else.
Full description and specifications ↓

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Product details

The Pentair 357255Z is the strainer cover o-ring, supplied in Buna-N at 70 durometer in the standard #2-357 size. It is the seal between the pump lid and the strainer pot.

What it does

Everything on the suction side of a pump runs under vacuum, so any gap there pulls air rather than leaking water. The strainer cover o-ring is the largest and most exposed of those seals, and it is the one that gets compressed and released every time somebody empties the basket.

When to change it

If the pump is slow to prime, holds air in the basket while it runs, or the lid has to be forced down to hold a seal, replace the o-ring before looking anywhere else. Keep it lubricated with a silicone based product intended for pool o-rings. Petroleum grease swells and degrades the rubber and will shorten the life of the new one.

Specifications
Brand Pentair
Manufacturer part number 357255Z
UPC 788379885779
Type Strainer cover o-ring
Material Buna-N
Durometer 70
Size #2-357
Shipping weight 0.06 lb
Ships Parcel

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Questions and answers

What people ask about this product, answered by our pool techs.

What is the part number?
Pentair 357255Z. The o-ring size is #2-357 in Buna-N 70 durometer.
Why does my pump lose prime?
The strainer cover o-ring is the usual suspect. Once it hardens or takes a set, it stops sealing against the lid and the pump draws air instead of water.
Should I grease it?
A silicone based lubricant made for pool o-rings keeps it supple and helps the lid seat. Petroleum grease will attack the rubber, so do not use it.
How do I know it needs replacing?
Look for flat spots, cracks, or an o-ring that has gone hard and no longer springs back. Any of those and it will not seal, no matter how hard the lid is tightened.
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