Product Overview

The Pentair 152509Z Closure Square Ring is a genuine OEM sealing ring designed for compatible Pentair Triton® C and Triton C-3 fiberglass sand filters.

Installed beneath the filter’s 8-1/2" closure, this square-profile sealing ring helps create a watertight seal between the closure assembly and the filter tank. It is an important service component whenever the filter is opened for maintenance or when an existing closure seal has become flattened, cracked, brittle, or damaged.

Pentair currently lists 152509Z as the Square Ring – Closure for Triton C/C-3 commercial fiberglass sand filters.

Where Is It Installed?

The 152509Z installs at the large top closure on the filter tank.

It seals between:

• The filter tank opening
• The 8-1/2" closure assembly
• The threaded closure components

When compressed properly, the square ring helps contain system pressure and prevent water leakage around the closure.

Key Features

Genuine Pentair OEM replacement part

Manufacturer Part Number: 152509Z

Closure square ring / gasket

Designed for Pentair Triton C and Triton C-3 filters

Used with the 8-1/2" filter closure

Square-profile sealing design

Helps prevent water leakage around the filter closure

Ideal for routine filter service and rebuilds

Direct replacement for worn or damaged original seal

Sold individually

Specifications

Related Pentair Triton C / C-3 Parts

Pentair lists these components together in its current Triton C/C-3 replacement-parts catalog.

Warranty & Compatibility

Compatibility

Pentair lists the 152509Z square ring in the replacement-parts breakdown for Triton C and C-3 sand filters, including commercial fiberglass filter configurations.

It is associated with compatible:

• Pentair Triton C
• Pentair Triton C-3
• TR100C
• TR140C
• Compatible TR100C-3
• Compatible TR140C-3

Pentair’s Triton 100C-3 and 140C-3 documentation also identifies the equivalent square-ring closure component as part number 152509.

Important Compatibility Note

Do not confuse this part with 152511Z, which is a different Quad closure O-ring used in certain filter configurations.

For current Triton C/C-3 applications, 152509Z is the square-profile closure ring.

When Should It Be Replaced?

Replace the closure square ring if you notice:

• Water leaking around the filter lid or closure
• Ring has become flattened
• Cracking or splitting
• Hard or brittle rubber
• Visible deformation
• Seal no longer seats evenly
• Ring was damaged during filter servicing

Replacing an aged closure seal is often inexpensive insurance against leaks after reassembling the filter.

Installation Information

Before opening or servicing a pressurized pool filter:

1. Turn the circulation pump off.
2. Shut off power to the equipment.
3. Open the manual air-relief valve.
4. Confirm the pressure gauge reads 0 PSI.
5. Remove the filter closure according to Pentair instructions.
6. Remove and clean the existing sealing surface.
7. Install the new 152509Z square ring evenly.
8. Reinstall the closure and tighten according to Pentair procedures.
9. Restart the system and inspect carefully for leaks.

Never attempt to loosen a filter closure while the tank is pressurized.

Customer-Facing Q&A

Q: What is Pentair 152509Z?
A: It is the 8-1/2" closure square ring used on compatible Pentair Triton C and Triton C-3 fiberglass sand filters.

Q: Is 152509Z an O-ring?
A: It serves the same sealing purpose, but Pentair specifically describes it as a square ring, meaning its cross-section differs from a conventional round O-ring.

Q: Does it fit TR100C?
A: Yes. Pentair lists 152509Z in the Triton C replacement-parts family, including TR100C applications.

Q: Does it fit TR140C?
A: Yes. It is also listed for compatible TR140C configurations.

Q: What happened to part number 152509?
A: 152509 is the older numbering seen in Pentair documentation. Pool360 currently shows 152509 as obsolete, while 152509Z remains the active listing.

Q: Is 152509Z the same as 152511Z?
A: No. 152511Z is a different Quad closure O-ring. Verify the filter and existing seal before ordering.

Q: Is the closure lid included?
A: No. 152509Z is the sealing ring only. The 8-1/2" closure is sold separately.