14 Reasons to Reduce Wear Ring Clearance

Use DuPont™ Vespel® CR-6100 to reduce the clearance in your pumps and improve pump reliability and efficiency.

Vespel CR-6100 Review

A couple weeks ago, we looked at all of the negative consequences from increasing the wear part clearance in you pumps: wear rings, inter-stage rings, throttle bushings, and center bushings. In the past, increasing the clearance was a typical response to pump seizure.

Now, there is a better way to address the issue and make your pump more reliable and efficient at the same time. Instead of increasing the clearance of the metal parts, replace the stationary wear parts with non-seizing, non-galling Vespel® CR-6100 and reduce the clearance. With this simple change, all the contact points in the pump become metal-to-composite and the risk of seizure is minimized.

What if you reduce the clearance?

Because Vespel® CR-6100 is non-seizing, you can safely reduce the clearance at the wear parts in your pumps. Even if the pump runs dry, Vespel® CR-6100 will not seize like metal components.



When you reduce the clearance at your wear parts, essentially every aspect of the pump hydraulic performance improves. Reduced clearance also tends to produce lower vibration levels. In short, the pump will likely be easier to operate, more reliable, and consume less power.


14 Benefits of Reduced Clearance using Vespel CR-6100 


Hydraulic Benefits Mechanical Benefits
Higher head Increased rotor stiffness
Higher flow–higher potential maximum flow rate Potentially lower vibration
Increased efficiency–reduced power consumption Potentially reduced shaft deflection
Lower NPSHR–lower risk of cavitation Reduced risk of shaft breakage
Reduced motor load Potentially longer seal life
Steam turbine drivers can run at lower speeds Potentially longer bearing life
Reduced need to run pumps in parallel Reduced potential for motor tripping or over-heating


The PERF-Seal™

The benefits of reducing the clearance can be augmented using the patented Boulden PERF-Seal™ design. The design is simple to implement, increases the potential efficiency gain from the upgrade, adds a significant amount of hydraulic damping, and generally amplifies the benefits of your upgrade to Vespel® CR-6100. Contact Boulden for details.

Two-stage product shipping pump upgraded with the PERF-SEAL deign

The Poster Pump, continued…

Two weeks ago, we wrote about an 11-stage horizontal pump which had seized several times. Each time it seized, the wear part clearance was increased. After the clearance had been increased multiple times, the pump would vibrate beyond alarm limits and the pump was no longer operable.

The plant upgraded the pump with Vespel® CR-6100 case rings, center bushing, and throttle bushing, using the Boulden PERF-Seal™ design. They subsequently reduced the clearance to less than the original design clearance. After the upgrade, the pump ran without seizing, very low vibration, and a significant efficiency gain.



What do you think of our list of benefits from reduced clearance? Is there anything we should add? Anything you disagree with? Let us know your ideas. We will be happy to hear from you.


Until next time, if you have a pump in your shop which can benefit from an upgrade to Vespel® CR-6100 and reduced clearance, contact Boulden. We can answer your questions and we have material in stock and available for immediate shipment.


Helpful Links:

Standard Stock Sizes of Vespel® CR-6100

Vespel® CR-6100 Product Data Sheet

Vespel® CR-6100 Machining Guide

3MW Boiler Feed Pump Case Study

Today’s Photo

Place Stanislas is considered to be one of, if not the most beautiful royal squares in Europe. It was added to UNESCO’s World Heritage List in 1983.

Contact Us Today To Learn More About Vespel and Boulden Company!



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