ASP STERRAD 100, Service Manual, Page: 90 / 309

Exhaust Filter
The exhaust filter is attached to the vacuum pump exhaust port. The air
evacuated from the process chamber during the sterilization cycle passes
through this filter before discharge into the atmosphere. The exhaust
filter contains two elements, an oil mist filter and carbon filter. They
must be replaced periodically.
Oil Return Valve
This part is on
Block 2
and STERRAD
100 S
Devices. The oil return
valve, a normally closed solenoid valve, is opened at the beginning of the
vacuum stage for 5 seconds or 10 seconds (STERRAD 100 S Systems) to
allow oil to return into the vacuum pump from the exhaust filter.
Throttle Valve
The throttle valve is operated by a digitally controlled stepper motor
driven butterfly valve with an O-ring seal. The seal has a leak through
rate of less than 2x10
-6
mbar times 1 liter/sec of helium when closed,
and a leak rate to the outside of less than 2x10
-6
mbar times 1 liter/sec
of helium. The valve is open during the vacuum stage, diffusion pump
down phase, and vent stage, and closed during the injection/diffusion
stage. The valve is precisely modulated to maintain the required vacuum
in the process chamber during the plasma stage.
Pump Intake Filter
The pump intake filter removes any residual hydrogen peroxide
withdrawn from the process chamber before it reaches the vacuum
pump, or is expelled into the room. This filter must be replaced
periodically.
HEPA Filter
Air admitted to the process chamber during the vent stage of the
sterilization cycle is filtered by a High Efficiency Particulate Air (HEPA)
filter. The HEPA filter removes dust and airborne organisms. The HEPA
filter must be replaced periodically.
Vacuum Subsystem Theory of Operation
4-4 STERRAD® 100 Sterilizer ASP Service Guide rev. D