CinchSeal | 23b Roland Avenue, Mount Laurel, NJ 08054 | Phone: 1-856-662-5162

CinchSeal / Rotary Shaft Seal Overview

Rotary Shaft Seals – An Overview

Air Purge SealRotary 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.

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.

Why the Competition’s Seals Fail

Air Purge SealWhile mechanical packing may be the most common sealing method you see in the field, it requires high maintenance and is ultimately ineffective. Standard gland seals such as packing glands or split gland seals use square packing that is compressed around the shaft to create a seal between the shaft and the housing. The packing is designed to wear with normal operation, and depending on the product being sealed, will frequently need to be replaced. The shaft’s axial runout also causes the packing to wear, creating gaps for material to leak out. By contrast, our rotary shaft seals can handle up to ¼” of shaft runout.

Rope packing seals are ineffective at handling abrasive bulk materials, which can migrate into the seal area and become impregnated into the rope packing. These materials will begin to wear down both the shaft and the packing, and create an area for material to escape. Packing also has to be maintained, removed, and re-packed, which is costly and labor intensive. CinchSeal products avoid this thanks to a self-adjusting design, resulting in almost zero maintenance for thousands of hours.

Internal Mechanism

Air Purge Seal
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:

  • Poly housing with air purge up to 180°F
  • Aluminum or 316 stainless steel up to 400°F

Can Withstand:

  • Up to 28 inches of vacuum
  • Up to 65 psi operating pressure
  • Purge seal with 5 to 7 psi of air above operating vessel pressure for optimum performance


  • Screw conveyor seal – up to 60 rpm
  • Mixer seal – up to 225 rpm
  • Chopper seal – up to 3600 rpm
  • Notify the factory when application is above 60 rpm for screw conveyor seal or 225 rpm for mixer seal
  • Maximum surface speeds approx. 1200 feet per minute


  • Seal housing is available in Aluminum and 316 Stainless Steel depending on customer needs
  • Hastelloy C 276 and titanium can be used when required

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