Mechanical pump seal
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978c Mechanical Seal (PS-978) – 1-1/4″
978c Mechanical Seal (PS-978) – 1-1/4″
Item #N/A
Single Spring Mechanical Seal 978C — 1-1/4″ | PS-978 Equivalent
978c single spring mechanical seal, PS-978 / 978 equivalent. Fits 1-1/4″ shaft with 1.765″×.365″ seat and Type N-33 (tapered spring) rotary head.
Typical applications: Centrifugal pumps, mixers, and other rotating equipment.
Key specs: Shaft size: 1-1/4″ single spring seal • Seat: 1.765″ x 0.365″ • Rotary OD: 1.787″ • Working length: 1.062″
Design & construction:
Crimped rotary head (Type N-33)—equivalent to Pac-Seal T-21 (tapered spring) and Burgmann MG9, can replace seal type D & 2 type seal heads. Tapered spring for wide base to fit over impeller hub or other similar feature. Electro-polished 304 stainless steel metal parts. Elastomeric bellows. Non-directional (independent of shaft rotation).
Materials available (choose from dropdown)
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CAR/CER/NIT — Carbon vs. Ceramic faces, Nitrile elastomers
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CAR/CER/VIT — Carbon vs. Ceramic faces, Viton elastomers
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SIC/SIC/VIT — Silicon Carbide vs. Silicon Carbide faces, Viton elastomers
Have questions? Check out our Single Spring Seal Guide or call us anytime—we’re here to help.
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.
Please click “specifications” below for OEM numbers and Pump Nameplate Data

SPS-278 Mechanical Seal (PS-278 Cup) – 2-3/8″
SPS-278 Mechanical Seal (PS-278 Cup) – 2-3/8″
Item #N/A
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)
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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:
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Heavier elastomer bellows for improved structural integrity and stability under pressure
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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.

SPS-279 Mechanical Seal (PS-279 Cup) – 2-1/2″
SPS-279 Mechanical Seal (PS-279 Cup) – 2-1/2″
Item #N/A
Single Spring Mechanical Seal SPS-279 | PS-279 cup Equivalent
SPS-279 is a single spring mechanical seal equal to industry standard 279 / PS-279 cup
Typical applications: Centrifugal pumps, mixers, and other rotating equipment.
Key specs: Shaft size: 2-1/2″ single spring seal • Seat: 3.375″ x .562″ cup • Rotary OD: 3.210″ • 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.

SPS-324 Mechanical Seal (PS-324 Cup) – 3″
SPS-324 Mechanical Seal (PS-324 Cup) – 3″
Item #N/A
Single Spring Mechanical Seal SPS-324 | PS-324 cup Equivalent
SPS-324 single spring mechanical seal, PS-324 / 324 cup equivalent. Fits 3″ shaft with 3.875″×.625″ seat and Type E/1 rotary head.
Typical applications: Centrifugal pumps, mixers, and other rotating equipment.
Key specs: Shaft size: 3″ single spring seal • Seat: 3.875″ x .625″ cup • Rotary OD: 3.770″ • Working length: 2.875″
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.

SPS-838 Mechanical Seal (PS-838 Cup) – 2-3/4″
SPS-838 Mechanical Seal (PS-838 Cup) – 2-3/4″
Item #N/A
Single Spring Mechanical Seal SPS-838 | PS-838 cup Equivalent
SPS-838 single spring mechanical seal, PS-838 / 838 cup equivalent. Fits 2-3/4″ shaft with 3.500″×.625″ seat and Type E/1 rotary head
Typical applications: Centrifugal pumps, mixers, and other rotating equipment.
Key specs: Shaft size: 2-3/4″ single spring seal • Seat: 3.500″ x .625″ cup • Rotary OD: 3.520″ • Working length: 2.875″
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.
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