Non Pusher Mechanical Seal

Product Overview

What is a Non Pusher Mechanical Seal?
A Non Pusher Mechanical Seal (commonly called a bellows seal or Non Pusher Seal) uses a static secondary seal and either an elastomer or metal bellows to accommodate axial movement and face wear. Unlike pusher (spring-loaded) designs, the secondary sealing element does not slide axially during operation, reducing the risk of seal hang-up and extrusion in many services. Non pusher seals are widely used where reliable static sealing, chemical compatibility and compact installation are required.

Common aliases (use across the page): Non Pusher Seal, bellows mechanical seal, bellows seal, non pusher bellows seal.

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Key Features & Design Options

Core features

• Static secondary seal (non sliding): reduces extrusion and hang-up risk in many fluids.

• Bellows compensation: elastomer bellows or metal bellows provide axial compliance and spring force without a dynamic O-ring.

• Elastomer and metal bellows variants: elastomer bellows for cost-effective general service; metal bellows for higher temperature, higher pressure or aggressive fluids.

• Component and cartridge formats: cartridge versions speed installation and reduce alignment errors.

• Modular replaceable face sets and elastomer kits for fast maintenance.

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Typical Technical Specifications

Final selection must be confirmed by seal drawing and application data. Values below are typical design envelopes used for quotation and stock selection.

• Seal type: Non pusher seal — elastomer bellows / metal bellows.

• Stock shaft diameters: 12, 16, 20, 25, 32, 40, 50, 63, 80, 100, 125, 130 mm (others available by request).

• Recommended maximum dynamic pressure:

  • Elastomer bellows: up to ≈ 8–10 bar (0.8–1.0 MPa) depending on face pairing and application.

  • Metal bellows: up to 20–40 bar depending on bellows design and metallurgy (consult engineering).

• Temperature range:

  • Elastomer bellows (typical elastomers): −40 °C to +150 °C (specific elastomer limits vary: EPDM, NBR, FKM/Viton, HNBR).

  • Metal bellows: −40 °C to +300 °C depending on alloy and face materials.

• Rotational speed (typical): up to 15–20 m/s surface speed for standard face pairs; verify for high-speed duties.

• Face materials: Carbon / Silica-based ceramics / Silicon carbide (SiC) / Tungsten carbide (TC) — chosen per media abrasiveness and lubrication.

• Elastomers: NBR, FKM (Viton), EPDM, HNBR, per media compatibility.

• Shaft finish & tolerance: ground to pump OEM recommended finish (typical Ra ≤ 0.8 μm); verify sleeve/hardness prior to installation.

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Common Sizes & Selection Guide

Common stocked shaft diameters (mm → inch approx.)

Selection checklist for a firm quote: shaft diameter, pump make/model, stuffing box dimensions or existing seal part number, process fluid, operating temperature, operating and test pressures, shaft speed (RPM), solids content, preferred face/elastomer materials, and whether cartridge or component style is required.

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Materials & Face Combinations

• Carbon (rotor) / SiC (stationary): economical run-in and good for many liquid services.

• SiC / SiC: highest wear resistance — recommended for abrasive or solids-laden fluids.

• TC / Carbon: heavy wear resistance for abrasive slurries.

• Ceramic / Carbon: good corrosion resistance with moderate wear.

Elastomer selection guidelines:

• NBR (Buna-N): petroleum-based fluids, moderate temperature.

• FKM (Viton): broad chemical resistance and higher temperature capability.

• EPDM: hot water and many alkaline environments.

• HNBR: improved heat and oil resistance over NBR.

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Typical Applications & Pump Types

Industries

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  Municipal water & wastewater treatment

• Chemical processing (corrosive and solvent services with metal bellows)

• Petrochemical (selected face/elastomer combinations)

• HVAC, district heating and cooling circuits

• Food & beverage (with compliant materials on request)

• Pulp & paper, mining (metal bellows + hard faces for abrasive services)

Pump types

• End-suction centrifugal pumps (ISO/ANSI)

• Close-coupled and frame-mounted pumps

• Vertical and submersible designs (where bellows geometry permits)

• Rotary equipment that benefits from static secondary sealing

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Performance, Installation & Maintenance

• Installation: Cartridge bellows seals are recommended to eliminate errors in axial set and simplify field swaps. Follow OEM torque and set height instructions when installing component seals.

• Lubrication / flush plans: For high temperature, vaporous or solids-laden services use an appropriate plan (flush, quench or buffer) to maintain film lubrication and prevent dry running.

• Maintenance: Keep face sets, bellows kits and elastomer spares for common shaft sizes. Inspect shaft sleeves for scoring and correct hardness before installing a new seal.

• Common failure modes: dry running, abrasive wear from solids, chemical attack on elastomers, bellows fatigue from thermal cycling — mitigate by selecting correct materials and support plans.

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Advantages of Non Pusher Mechanical Seals

• Static secondary sealing reduces extrusion/hang-up risk compared to pusher seals in many fluid types.

• Simplified axial compensation (bellows provides springing action without moving secondary O-rings).

• Better chemical compatibility in metal bellows variants for aggressive media and elevated temperatures.

• Compact compactness and reliability for applications where a moving secondary seal is undesirable.

• Cartridge options offer fast swap and minimal alignment adjustments.

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Non Pusher vs Pusher vs Other Sealing Options

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Downloadable Resources

• Download: Full Mechanical Seals Catalogue (PDF)

• Download: Non Pusher Mechanical Seal Technical Data Sheet (PDF)

• Download: Non Pusher Mechanical Seal Specifications (PDF)

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FAQ

Q1: When should I select a Non Pusher seal instead of a pusher seal?
A: Choose a Non Pusher Seal when you require a static secondary seal to avoid axial sliding (reduces extrusion/hang-up), when chemical compatibility or elevated temperature dictates metal bellows, or when a compact bellows solution fits the stuffing box. Provide pump details for confirmation.

Q2: What information do you need to provide an accurate quote?
A: Shaft diameter, pump OEM & model or existing seal part number, stuffing-box dimensions, process fluid, operating temperature, working and hydrostatic test pressures, RPM, solids content, preferred face and elastomer materials, and required delivery.

Q3: Are elastomer bellows suitable for wastewater with solids present?
A: Elastomer bellows can be used for some wastewater services but have lower abrasion tolerance than metal bellows. For solids-laden or highly abrasive streams we recommend hard face materials (SiC/TC) and consider metal bellows designs or appropriate flush plans.

Q4: Do you offer cartridge bellows seals for fast replacement?
A: Yes. Cartridge configurations for popular ISO/ANSI pumps are available to speed installation and minimize field errors.

Q5: What testing and documentation accompany each seal?
A: Each shipment includes dimensional drawings, material declarations and QA test records; test certificates and inspection reports can be provided per purchase order.

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E-E-T-A

To strengthen buyer confidence and satisfy search quality expectations include concrete, verifiable E-E-T-A content on your published page:

• Experience (Example copy to adapt): “Our rotating-seal group has supplied bellows and cartridge solutions for municipal and process plants for 20 years, delivering retrofit and OEM contracts worldwide.”

• Expertise: “Seal selections are validated by our engineering team using pump OEM cross-reference checks, dimensional verification and application review to ensure correct material pairing and support-plan selection.”

• Authoritativeness: “Products are produced and inspected under documented QA procedures; material certificates and dimensional drawings accompany each order.”

• Transparency: “We disclose material compositions, typical working envelopes and service limitations before purchase. For critical duties we provide engineering recommendations and on-site support options.”

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Why choose our Non Pusher Mechanical Seals

• Stock for common shaft sizes (12–130 mm) for rapid dispatch.

• Elastomer and metal bellows options to match operating envelopes.

• Cartridge and component choices for retrofit or OEM fitments.

• Technical support: application review, dimensional confirmation and on-site troubleshooting.

• Spare kits (face sets, bellows and elastomer kits) available to reduce mean time to repair.

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Contact & Ordering

Hengshui Aohong — Seals Division

• Email: sales@aohongglobal.com (for datasheet requests and fast quotes)

• Phone: +(86) 153 7318 1024 (please replace with your official number)