Brass leak-off ring 20mm AQ

The 20 mm brass leak-off ring is a service part used in the pump seal assembly, designed to work with low-pressure (LP) seals. In workshop practice, “leak-off” elements act as an intermediate part in the sealing zone-supporting proper working conditions and controlled flow/drainage around the seal area.

MPN / reference: 40509
Reference dimension: Ø 20 mm

APPLICATION

Used in typical pump service work:

• overhauling the low-pressure seal assembly,
• replacing the intermediate element in the sealing zone during a pump rebuild,
• restoring correct seating and cooperation of low-pressure seals,
• servicing pumps where brass elements in the sealing area show wear.

SYMPTOMS - WHEN IT IS WORTH REPLACING

Consider replacing the ring if you notice:

• recurring sealing issues in the low-pressure seal area,
• wear marks, scratches, or pitting on cooperating surfaces,
• deformation or mechanical damage after disassembly,
• reduced stability of the seal assembly after reassembly,
• leaks returning despite replacing the seals themselves (after excluding other causes).

HOW TO CHOOSE THE RIGHT PART

Selection should be unambiguous:

• confirm it is the “leak-off” ring for the low-pressure seal set,
• verify the manufacturer number: MPN 40509,
• check the Ø 20 mm reference dimension and compare geometry with the removed part,
• base selection on the pump service documentation.

In the sealing zone, profile and fit are critical-parts with a similar diameter are not necessarily interchangeable.

COMPATIBILITY

Select the ring based on MPN 40509 and compatibility with the low-pressure seal assembly used in the specific pump. Ø 20 mm is only a dimensional hint; the primary identifier is the manufacturer number and comparison with the removed part.

[faq]

What does “leak-off ring” mean?|It refers to a component working in the sealing zone that is tied to controlled leakage/drainage in the seal area. In practice, it’s important to use the exact specified variant.

Does this ring work on the high-pressure side or the low-pressure side?|By designation it is for low-pressure seals, so it belongs to the LP zone of the pump, not directly to the high-pressure sealing side.

Does it make sense to replace only the LP seals without the ring?|Sometimes yes, but if the ring shows wear or damage, new seals may not run correctly. During a rebuild the entire seal assembly is typically assessed, not only the elastomer parts.

Is “Ø 20 mm” enough to select the correct part?|No. It’s only a dimensional hint. The safest method is selecting by MPN 40509 and comparing the geometry with the removed ring.

What should be checked when replacing the ring in the LP zone?|Inspect seats, mating surfaces, guiding elements, and the remaining seals in the assembly. Wear in these areas can cause recurring issues even after replacing parts.

[/faq]