Cartridge Mechanical Seals for Industrial Pumps
Pre-assembled mechanical seals selected for your pump, fluid and operating duty
Quick Answer:
A cartridge mechanical seal is a pre-assembled unit with seal faces, secondary seals, a sleeve and a gland. The seal is set as an assembly rather than built up from separate parts at the pump. The assembly still has to fit the seal chamber and suit the operating duty.
What a cartridge mechanical seal includes
The rotating and stationary seal faces control leakage at the shaft. Secondary seals close the leak paths behind the faces. The sleeve and gland hold the assembly together, with the setting position established before installation. Follow the installation instructions for the selected seal, including the setting clips and any flush connections.
A cartridge is an assembly format, not a material grade or a guarantee of service life. Face materials, elastomers, arrangement and seal support have to match the fluid and the pump.
How a cartridge seal works, in 49 seconds
From the gap every pump shaft needs, to the two flat faces that stop it leaking. The working length is set in the factory, so there is nothing to measure on site.
Single or double cartridge seal?
A single mechanical seal has one face pair. A double arrangement has two face pairs and needs the correct barrier or buffer fluid support. The choice depends on the process fluid, whether leakage to atmosphere is acceptable, and whether the faces have a reliable lubricating film.
Hazardous, crystallising or abrasive fluids need a duty-specific check. A double seal is not an automatic upgrade for every pump. Send the fluid, concentration, temperature, pressure and operating conditions so the arrangement and support system can be checked.
Balanced and unbalanced seals
Balance changes the hydraulic closing force on the seal faces. Pressure and shaft speed are part of that selection. Do not assume that every cartridge seal is balanced or use a general pressure rating in place of the selected seal's limits.
Use the mechanical seal selection guide to work through the fluid, temperature, pressure, speed and equipment condition.
Cartridge seal or component seal: which should I choose?
A cartridge seal arrives assembled on its sleeve and gland. A component seal is fitted as separate rotating and stationary parts, with the working length set during installation. The cartridge reduces setting work at the pump. It still has to fit the seal chamber and suit the fluid and operating duty.
Start with the pump, not the price of the seal. Check the available space, shaft or sleeve diameter, chamber dimensions, gland fixings and any flush connections. Then check the fluid, temperature, pressure and speed.
A cartridge can reduce assembly errors. It does not remove the need to check pump alignment, shaft movement, lubrication and material compatibility. If the same seal keeps failing, find the cause before ordering another one.
What should I send for a cartridge seal quote?
Send the pump make and model, existing seal reference and clear photographs of the complete seal, gland and pump. Include the shaft or sleeve diameter, chamber bore and depth, gland fixing details and space available around the seal.
Tell us what the pump handles, including concentration and solids. Add the operating and maximum temperature, seal chamber pressure, shaft speed, cleaning cycles and any flush or barrier system. If it has failed, tell us when the leak started and keep the failed parts.
Keep a cartridge assembly and its setting parts together. Follow its manufacturer's instructions before dismantling it. Dimensions show what can fit. The operating duty tells us what should be supplied.
See the component seal page, mechanical seal measurement guide and leaks after installation guide.
Replacing gland packing with a cartridge seal
A conversion needs a stuffing box, shaft and duty check. Some pumps need a different gland or sleeve; others need more extensive changes. Read when gland packing can be replaced with a cartridge mechanical seal.
See the Robuschi pump cartridge seal conversion example and video for an existing conversion, rather than a promise that every pump can take the same seal.
If a cartridge seal keeps failing
Replacing the assembly without checking the failure can repeat the problem. Dry running, loss of flush, chemical attack, abrasive solids, misalignment, pipe strain and the wrong face pairing are all checks to make. Keep photographs of the failed faces and note when the leakage started.
Read why a mechanical seal leaks and what to check when replacing a pump mechanical seal. Acumen also arranges mechanical seal refurbishment through specialist partners; suitability is checked before that route is recommended.
Can a cartridge seal be repaired?
Sometimes. Inspection decides whether the assembly is suitable for refurbishment and which parts need replacing. Compare the repair scope, quoted cost and lead time with a correctly specified replacement.
Acumen arranges mechanical seal refurbishment through specialist partners. A repair is not a reason to repeat the same specification if the fluid or operating conditions caused the failure.
Read about mechanical seal refurbishment.
Request a cartridge seal quotation
Send the pump details, seal reference or dimensions, fluid, temperature, pressure, speed and photographs. Include the current fault and any required standard so the specification can be checked before a quotation.
Dispatch typically takes 2 to 3 days unless the item is stocked. The quotation confirms the specification, price and lead time for the selected seal.
We reply in working hours.
Free Troubleshooting Guide
Contact Acumen for our comprehensive seal diagnosis checklist
Download GuideCartridge Seals Questions and Answers
What is a cartridge mechanical seal?
A complete seal unit - faces, sleeve and gland - assembled and set before it reaches you. It slides onto the shaft as one piece and bolts to the pump, with no separate working-length setting during installation. The maker's installation checks still apply.
Why choose a cartridge over a component seal?
Installation error is the biggest cause of early seal failure. A cartridge removes the two most common mistakes - wrong installed length and faces damaged during assembly - and it shortens installation time, so the pump is back running sooner.
Single or double cartridge - which do I need?
Single for clean, non-hazardous duties. Double with a barrier or buffer fluid where the product is toxic, abrasive, crystallising, or must not reach atmosphere. Send us the duty and we will tell you which.
Which makes do you supply?
We are independent and select and supply cartridge seals across the major manufacturers, chosen against your duty rather than a brand preference.
Ask about cartridge seals
Send the pump details, dimensions and operating duty so Andrew can check the cartridge seal specification before quoting.
Prefer WhatsApp or email? Send the photographs with your name and the pump details so we can match them to your enquiry.