Rotary Shaft Seals – An Overview

Rotary shaft seals by CinchSeal are ideal for bulk handling and processing equipment across various industries. Designed to seal powders, slurries, and bulk materials, they reduce product loss and downtime for repairs.

Benefits of CinchSeal Rotary Shaft Seals

Cost savings: Eliminate product loss through leaks, reduce maintenance costs, and prevent shaft wear and bearing failure.

Durability: Designed to withstand the most rigorous environments in industrial food and bulk material processing.

Safety: Ensure the safety of employees in their work environment by minimizing area contamination.

Repairs: All our shaft seals accommodate repair / rebuild kits.

Rotary Shaft Seal Success Stories

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How Our Rotary Shaft Seal Works

PTFE or hard-coated aluminum rotor cups are mounted on the silicone boot and turn with the shaft to create the primary seal face with the stator plates. The stator plates are the sacrificial surfaces and are designed to wear.

Because the cups are mounted to the boot, the rotary assembly floats with the shaft accepting ¼” misalignment common to bulk handling equipment.

Why We Air Purge Our Seals

Rotary seals by CinchSeal are purged with air, or silicone grease if air isn’t available. If grease is used, the customer must apply enough grease to fill the whole cavity until you start to see grease leaking out of the Teflon® faces. We prefer the customer to use air, but understand it isn’t always an option. When you use air purge seals, there are 3 major things to remember:

1) When the air is piped from existing plant air directly into the seal, it creates pressure to push the rotor against the stator and closes the sliding interface to stop any material from going into or out of the screw conveyor.

2) We tell people to set their air gauges 5 to 7 psi higher than the vessel pressure, so that we have a higher pressure inside the seal than outside of it, creating an air barrier to keep product out of the seal.

3) The air keeps the rotating seal faces cooler by reducing heat caused by friction. This helps prolong the life of the seal as well. From our experience, customers usually get 1 to 2 times longer life out of their seals when they use air.

Rotary Shaft Seal Exploded View

Internal Mechanism

Rotary Shaft Seal Exploded View

The molded elastomer boot seals the shaft statically without damaging or wearing the shaft or the shaft seal material.

The silicone boot will withstand temperatures up to 425 degrees F.

The elastomer boot material is an FDA approved silicone that will handle 95% of industrial applications in the field. This lowers inventory and price, and reduces material selection errors.

Parts of the Seal

The PTFE stators and rotor cups are made out of special mineral filled Teflon® with 15% of a binding agent Wollastonite.
The hard coat aluminum rotor cups used for abrasive applications are rated at a rockwell hardness of 62, which is just below diamond.


Temperature Ranges

Silicon And PTFE Internal Parts Are Good Up To 425 °F – Higher Temperature
Applications Are


Poly housing with air purge up     to 180°F


Aluminum or 316 stainless steel housing up to 400°F

Can Withstand

Up To 28” Of Vacuum

Up To 45 Psi Operating Pressure

Purge Seal With 5 To 7 Psi Of Air Above Operating Vessel Pressure For Optimum Performance



Maximum Surface Speed – Approximately 270 Ft/Min

(5” Shaft @ 200 Rpm, Some Applications Run Up To 400 Rpms


Stainless Steel built  for frequent washdowns

Aluminum housing for a light, more affordable option

CinchSeal is a trusted and experienced rotary shaft seal manufacturer. Contact us to learn more about rotary seals or to get industrial seals for your business!

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Rotary Shaft Seals

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