Pump Throat Bushings

Dupont Vespel throat bushings

Vespel® CR-6100 throat bushing for multi-stage horizontal pump

What Does A Throat Bushing Do?

A throat bushing in a pump isolates the mechanical seal environment from the overall flow within the pump. By changing the clearance at the throat bushing, pressure in the seal chamber and seal flush flow rate can be manipulated to provide a better sealing environment.

Many mechanical seal flush plans use a “close-clearance” throat bushing to accomplish this. For example:

  • Plans 11 & 14 use a close-clearance throat bushing to build pressure in seal chambers
  • Plans 21 & 23 use close-clearance throat bushings to isolate cooled fluid from hot process liquids
  • Plan 32 uses a close-clearance throat bushing to isolate clean external flushes from dirty or corrosive process fluids

Why Use Vespel® or B-Series for throat bushings?

Several API 682 seal flush plans require close-clearance throat bushings to function properly. Many of these designs rely on “floating” spring-positioned carbon bushings.

DuPont™ Vespel® CR-6100 and Boulden B-Series composite materials are ideal materials for throat bushings and an effective replacement for carbon. They are durable, impact-resistant, and thermal shock resistant materials that is easy to machine. Vespel® CR-6100 has a low wear rate for long working life in any application. And, because the material is non-seizing, solid Vespel® bushings can be used in place of floating carbon bushings.

How to Get the Most Out of Your Throat Bushings

  • Replace the existing throat bushing material with Vespel® CR-6100 or B-Series
  • Use the clearance recommended by the mechanical seal manufacturer for your flush plan

Benefits of composite material throat bushings

  • Low wear
  • Impact and thermal shock resistant
  • Easy to machine and install

Contact us to learn more about pump throat bushings

Request a quote on upgrading your throat bushing applications to Boulden B-Series. Or, contact Boulden with your application details. We have the material you need in stock and ready to ship. You can also learn more about upgrading your pump throat bushings by signing up for our newsletter!