Page 239 - WaterSense at Work

October 2012
Steam Sterilizers
facility-specific cost of water and wastewater. A tempering water retrofit typically costs
If the steam sterilizer was replaced, use the cost of the new steam sterilizer.
Steam Sterilizer Retrofit or Replacement With Additional Ejector (Vacuum
Water Use)
Sterilizers can consume water to produce a vacuum. To reduce this water use, exist-
ing steam sterilizer equipment can be retrofitted or new units purchased with an
additional ejector with a pump and water reservoir to capture and reuse a portion
of the water passing through the ejector. Purchasing a new steam sterilizer with this
vacuum configuration would require a longer payback period.
Current Water Use
To estimate the current water use of an existing steam sterilizer’s vacuum, identify
the following information and use Equation 7-6:
Flow rate of water needed to pull the required vacuum. This will be dependent
upon the size of the unit.
Number of sterilization cycles run each day.
Duration of the conditioning phase. The average conditioning phase lasts three
Duration of the exhaust phase. The average exhaust phase lasts 30 minutes.
Days of sterilizer operation per year.
Equation 7-6. Steam Sterilizer VacuumWater Use (gallons per year)
= [Vacuum Flow Rate x (Duration of Exhaust Phase + Duration of
Conditioning Phase)] x Sterilization Cycles x Days of Operation
Vacuum Flow Rate (gallons per minute)
Duration of Exhaust Phase (minutes per cycle)
Duration of Conditioning Phase (minutes per cycle)
Sterilization Cycles (sterilization cycles per day)
Days of Operation (days of sterilizer operation per year)
Escalated from 2004 dollars to 2010 dollars; 2004 dollars from: Koeller, John, et al.,
op. cit.
Page 32.
Koeller, John, et al.,
op. cit
Pages 26-32.
Page 26.