INDUSTRY COMPONENT

Secondary Seals

Secondary seals are elastomeric or polymeric components in mechanical seals that provide static sealing between rotating and stationary parts, preventing fluid leakage along the shaft.

Component Specifications

Definition
Secondary seals, also known as static seals or O-rings in mechanical seal assemblies, are critical components that create a leak-proof barrier between the rotating shaft and stationary housing. They compensate for minor misalignments, thermal expansion, and vibration while maintaining sealing integrity under varying pressures and temperatures. These seals are typically installed in gland plates or seal chambers and work in conjunction with primary sealing faces to ensure complete fluid containment in pumps, mixers, and rotating equipment.
Working Principle
Secondary seals operate on the principle of elastic deformation and compression. When installed in a gland or housing groove, the elastomeric material (such as rubber or PTFE) is compressed radially or axially, creating continuous contact pressure against both sealing surfaces. This compression generates a static seal that prevents fluid passage along the shaft or housing interface. The seal maintains contact through elastic recovery forces, accommodating minor movements while resisting extrusion under pressure.
Materials
Common materials include: Nitrile Rubber (NBR) for general purposes (-40°C to 120°C, petroleum-based fluids), Fluorocarbon (FKM/Viton) for high-temperature chemical resistance (-20°C to 200°C), Ethylene Propylene Diene Monomer (EPDM) for steam and hot water (-50°C to 150°C), Perfluoroelastomer (FFKM) for aggressive chemicals (-20°C to 300°C), Polytetrafluoroethylene (PTFE) for chemical inertness (-200°C to 260°C), and Silicone (VMQ) for food-grade applications (-60°C to 230°C).
Technical Parameters
ParameterTypical rangeNotes & selection driver
Hardness70-90 Shore A (elastomers)
Pressure RangeUp to 40 bar (static)
Compression Set<25% (after 24h at 150°C)
Temperature Range-60°C to 300°C (material dependent)
Fluid CompatibilityBased on material selection
Cross Section Diameter1.78mm to 8.4mm

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards
ISO 3601-1, ISO 6194, AS 568A, DIN 3771, SAE J515

Parent Products

This component is used in the following industrial products

Engineering Analysis

Risks & Mitigation
  • Chemical incompatibility causing swelling/deterioration
  • Extrusion under high pressure
  • Thermal degradation exceeding temperature limits
  • Installation damage from sharp edges
  • Compression set leading to leakage
FMEA Triads
Trigger: Chemical attack from incompatible fluids
Failure: Seal swelling, softening, or cracking
Mitigation: Select chemically resistant materials (FKM, FFKM, PTFE) based on fluid analysis
Trigger: Excessive temperature beyond material limits
Failure: Thermal degradation, hardening, or compression set
Mitigation: Verify operating temperatures and select high-temperature materials (FFKM, silicone) with appropriate safety margins
Trigger: Improper installation or groove design
Failure: Rolling, twisting, or extrusion damage
Mitigation: Follow installation guidelines, use proper tools, ensure groove dimensions per standards, and deburr all edges

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance
±0.10mm on cross-section diameter, ±0.20mm on inside diameter (per ISO 3601-1)
Test Method
Pressure testing per ISO 5208, compression set per ASTM D395, fluid compatibility per ASTM D471, hardness per ASTM D2240

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation
Request current drawings, revision history, and a signed specification sheet.
Manufacturing capability
Verify equipment lists, process limits, capacity, and representative production evidence.
Inspection readiness
Confirm test methods, calibrated equipment, sampling plans, and traceable reports.
Supplier transparency
Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Secondary Seals

Manufacturer profiles associated with Secondary Seals.

Sourcing Secondary Seals from China?
Tell us your specification and target quantity — we will match it against manufacturer records and come back with the factories that fit.
Request manufacturers We manufacture this

Manufacturer listings support early research and capability understanding. They are not certification, ranking, or transaction guarantees.

Related Components

Upper Tool (Punch)
Upper Tool (Punch) is the active forming component in metal plate bending machines that applies precise downward force to create bends in sheet metal.
Main Frame
The main frame is the primary structural component of a hydraulic press, providing rigidity and stability to withstand high compressive forces during metal forming operations.
Shaft Bearing
Precision component supporting rotating shafts in vibration motors to reduce friction and maintain alignment.
Seal Groove
Precision-machined groove in aluminum bearing housings designed to accommodate sealing elements for fluid containment and contamination prevention.

Frequently Asked Questions

What is the difference between primary and secondary seals in mechanical seals?

Primary seals are the main sealing faces (usually rotating/stationary faces) that handle dynamic sealing, while secondary seals provide static sealing between components and compensate for misalignments.

How often should secondary seals be replaced?

Replacement depends on operating conditions, but typically during mechanical seal overhaul (every 1-3 years) or when signs of hardening, cracking, or compression set exceed 25%.

Can secondary seals handle abrasive fluids?

Standard elastomers may degrade with abrasives; PTFE or FFKM materials with anti-extrusion rings are recommended for abrasive service.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification
This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Request Manufacturing Insight for Secondary Seals

Thank you. Your request has been sent. We'll respond within 1–3 business days.
Sorry, we couldn't send your message. Please try again, or email us at contact@cnfx.com.
Seals and Bearings Sector Gear
Get QuotesChat