October 2012
7-17
7.4
Steam Sterilizers
Newer steam sterilizers can be designed—or older systems retrofitted—with a ther-
mostatically actuated valve (see Figure 7-3) and/or an uninsulated heat exchange
tank to significantly reduce the amount of tempering water use. The heat exchange
tank transfers heat from the condensate to the cooler, ambient atmosphere before it
is discharged to the sanitary sewer. The tempering valve allows tempering water to
flow only when the condensate reaches a certain temperature. Major steam sterilizer
manufacturers in the United States began including water tempering kits on their
systems in the late 1990s.
Figure 7-3. Steam Sterilizer CoolingWater Retrofit
Steam sterilizers can also be retrofitted or designed to reduce the amount of water
necessary to draw a vacuum through the sterilization chamber. In a conventional
steam sterilizer, the vacuum is generated by passing water at a high velocity through
an ejector at a flow rate of 5.0 to 15.0 gpm and discharging it directly to the sanitary
sewer.
28
To reduce this water use, a second pump and water reservoir can be added to
capture and reuse a portion of the water. New steam sterilizers can also offer an elec-
tric liquid-ring vacuum pump that reduces water use by about 75 percent compared
to the water used through the vacuum generation on a conventional steam sterilizer.
29
28
Koeller, John, et al. August 2004.
A Report on Potential Best Management Practices
.
Prepared for the California Urban Water Conservation Council. Pages 26.
29
Ibid
.
Page 31.
Sterilization
Chamber
Tempering
Water
Condensate
Temperature Sensor
Thermostatically
Actuated
Valve
Cooled
Condensate
Wastewater to
Drain
<140°F
Jacket
Steam Supply
