Mechanical Seal

Back in the day we used to refer to the throttle bush as a "disaster bush". (Throttle bush is the correct term, but disaster bush is more descriptive of its function).

The throttle bush is a close tolerance mechanical bushing made of non-sparking material that restricts the escape of the pumped fluid in case of a catastrophic seal failure. For API 610 pumps this should now be a floating ring seal.

It is not required when dual seals are fitted, but I would strongly recommend that one be fitted if there is adequate space if you are pumping a flammable or dangerous product.

The throttle bush is also utilised to minimise leakage in cases where a seal quench is used.