An end user’s decision on whether to use a water ejector or vacuum pump to generate sterilizer-vacuum is largely based on the following parameters:

  • Sterilizer chamber size
  • Time required to generate the necessary vacuum
  • Relative purchase price of the system
  • Maintenance requirements and system longevity
  • Water usage
  • Electrical power usage

Nationally, most facilities opt for the water ejector on Small steam sterilizers.

Ejectors are much less expensive than vacuum pumps to purchase and maintain. They are simple in design and function as they have no moving parts.

An increasing number of customers are also ordering PRI-Saver™ Water Conservation Systems to help with LEED compliance and utility cost reduction.

Medium sterilizers are split between water ejectors and electric vacuum pumps depending on end-user preference.

Large (bulk) PRIMUS steam sterilizers are always supplied with a SIHI-brand electric vacuum pump.

At a certain vessel chamber volume, the time required to pull a full vacuum becomes the key deciding factor on which type of vacuum system to use.

Vacuum pumps are more water-efficient than ejectors in large sterilizers.

PRIMUS can provide SIHI electric vacuum pumps in sizes from 2 Hp to 20 Hp.

Have a question or having difficulties? Talk to Dave Schall, our PRIMUS sterilizer expert who is here to assist you anytime at 877.679.7800 extension 1212 or email at

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