Single Spring Mechanical Seal SPS-278 | PS-278 cup Equivalent

SPS-278 is a single spring mechanical seal equal to industry standard 278 / PS-278 cup.

Typical applications: Centrifugal pumps, mixers, and other rotating equipment.

Key specs: Shaft size: 2-3/8″ single spring seal • Seat: 3.250″ x .562″ cup • Rotary OD: 3.083″ • Working length: 2.500″

Design & construction:
Rotary head Type E/1. Electro-polished 316 stainless steel metal parts. Elastomeric bellows. Non-directional (independent of shaft rotation).

Materials available (choose from dropdown)

• CAR/CER/NIT — Carbon vs. Ceramic faces, Nitrile elastomers

• CAR/CER/VIT — Carbon vs. Ceramic faces, Viton/FKM elastomers

• SIC/SIC/VIT — Silicon Carbide vs. Silicon Carbide faces, Viton/FKM elastomers

Please click “specifications” below for OEM numbers and Pump Nameplate Data

SPS Line

Same Fit. Lasting Reliability.

Our SPS single-spring seals are like-for-like replacements for industry-standard E/1, D/2, and C/21 heads—delivering the same fit and function with upgraded materials designed for extended service life.

What sets SPS apart:

• Heavier elastomer bellows for improved structural integrity and stability under pressure

• Resin-impregnated, abrasion-resistant carbon faces — double-density carbon designed for enhanced hardness and durability

• 316/304 stainless steel components for superior corrosion protection across E/1, D/2, and C/21 head styles

• Precision-finished rotary heads with a brushed appearance for a high-quality machined look and consistent sealing performance

• Built to exacting standards for dependable performance across a wide range of pump applications

Engineered to rigorous standards, SPS seals provide a durable, dependable alternative to common aftermarket or OEM options—compare them against your current line and see the difference.

Explore our full lineup of Single Spring Seals—PS replacements, pool/spa seals, and our SPS line.

Looking for more? Shop Pump Repair Kits, Parts & Accessories, and  Gaskets.