A filter housing quotation that says only “O-ring included” leaves a critical compatibility question unanswered. The cover seal contacts the process liquid and is exposed to temperature, pressure cycles, cleaning chemicals and repeated opening. Buyers should identify the elastomer or encapsulated seal in the purchase specification and confirm it against the complete operating environment.
This RFQ guide covers seal selection for single bag, multi-bag and other liquid filter housings. It does not replace the seal manufacturer’s chemical compatibility review or the housing manufacturer’s approved spare-parts list.
Understand the material names
- Buna-N or NBR: nitrile rubber; commonly offered in industrial housing ranges.
- EPDM: an elastomer option with a different chemical and temperature profile from NBR.
- FKM: fluoroelastomer; Viton is a brand name used in some supplier literature.
- PTFE-encapsulated elastomer: a composite seal in which a PTFE jacket surrounds an elastomer core; it is not the same as a solid PTFE gasket.
- Silicone: offered for selected duties, but suitability depends on process and compliance requirements.
Eaton’s housing spare-parts literature lists Buna-N O-rings as standard for certain housings and EPDM, Viton/FKM, PTFE-encapsulated Viton and silicone as available options. That shows why the material must be specified, but it does not mean every option fits every Eaton or INCE housing.
Chemical compatibility is a starting screen
Compatibility tables are useful for narrowing candidates, not issuing final approval. Concentration, temperature, exposure time, pressure, mixtures, contaminants and cleaning cycles can change seal behavior. A material rated acceptable for one pure chemical may swell, harden, soften or lose sealing force in a real mixture.
Provide the chemical name and concentration for every normal, cleaning and upset fluid. Include pH only as supporting information; pH alone does not identify solvents, oxidizers or additives. Where the process fluid is proprietary, ask the chemical supplier and seal supplier to review the safety data sheet and service conditions.
Temperature and pressure cycling
The seal must remain elastic enough to follow the cover and resist extrusion or compression set within the approved housing design. State minimum startup temperature, normal operating temperature, maximum upset temperature, steaming or hot-water cleaning conditions, and whether the vessel cycles between ambient and process temperature.
Do not copy a generic elastomer temperature range into the purchase order as a housing guarantee. The usable limit can be lower because of chemical exposure, groove design, pressure, cycle frequency or regulatory requirements. Require the housing supplier to confirm the selected seal for the quoted assembly.
RFQ data table
| RFQ field | Information required |
|---|---|
| Process liquid | Names, concentrations, additives and contaminants |
| Cleaning fluids | CIP chemicals, concentration, temperature and exposure time |
| Temperature | Minimum, normal, maximum and cycle frequency |
| Pressure | Operating, design, vacuum and depressurization cycles |
| Seal form | O-ring, flat gasket or encapsulated profile; dimensions and drawing |
| Compliance | Food, pharmaceutical or customer-specific declarations if required |
| Identification | Material code, color if controlled, part number and batch traceability |
| Spares | Quantity per housing and recommended replacement interval/inspection |
Fit is as important as polymer
An O-ring with the correct elastomer but wrong cross-section, diameter or hardness may leak or be damaged during closure. The groove and mating surfaces belong to the housing design. For replacement seals, send the housing manufacturer, model, serial number, seal part number and measured dimensions, but do not substitute only from measurements if the original profile is available.
Inspect sealing faces for damage and contamination. Eaton’s POLYLINE installation manual instructs users to ensure sealing surfaces and the cover O-ring are clean and damage-free before closing. Use only a lubricant approved for both the seal and process; an incompatible lubricant can create swelling, contamination or compliance problems.
Acceptance and change control
For critical service, request a certificate of conformity or material declaration tied to the delivered seal batch. Agree how seal material is marked or packaged to prevent mix-ups. If a supplier proposes changing from NBR to EPDM or FKM, treat it as a controlled change: repeat compatibility review, update the spare-parts list and confirm that the new seal is approved for the housing groove.
Leak testing should follow the housing supplier’s procedure and site rules. A passing static leak test does not prove long-term compatibility; inspect the seal after defined operating cycles for swelling, cracking, flattening, adhesion or loss of elasticity.
Link the seal choice to the full housing RFQ
Keep the seal decision with the pressure data sheet, connection specification and surface-finish requirement. The material statement should appear on the approved drawing and spare-parts list.
Request a seal-defined quotation
Send Your Specification with all process and cleaning fluids, concentrations, temperatures, pressures, housing model, seal dimensions, compliance requirements and annual spare quantity. Ask INCE to identify the quoted seal material and part number and to state any validation required.
FAQ
Is Viton the same as FKM?
Viton is a registered brand name for fluoroelastomer products. An RFQ should state the required generic FKM type or approved branded compound rather than assuming all FKM compounds are identical.
Can pH alone determine the correct O-ring?
No. The full chemical composition, concentration, temperature and exposure conditions are required.
Can a PTFE-encapsulated seal replace any elastomer O-ring?
No. Its stiffness, profile and installation behavior differ. Use it only when approved for the specific housing groove and service.
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