A366-04-880 Issue A
Page 4 © Edwards Limited 2014. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Introduction
For manual control, use the gas-ballast control (Figure 1, item 1). The pumps are supplied with an open-gas-ballast
inlet. If you leave this inlet open to the atmosphere, then:
With the gas-ballast control (Figure 1, item 1) open, when you switch the pump off, the pressure inside the
pump will rise to atmospheric pressure.
With the gas-ballast control closed, when you switch off the E2M175 and E2M275 pumps the vacuum will be
maintained inside the pump.
For remote control, fit a solenoid-operated gas-ballast control valve (available as an accessory from Edwards, refer
to Section 7) to the gas-ballast inlet and open the gas-ballast control. Connect the gas-ballast valve to your control
system so that the valve is closed when the pump is switched off and if the electrical supply to the pump is
interrupted. Under these circumstances, when the pump is switched off, the vacuum will be maintained inside the
pump.
It should be noted that when the pump is switched off the system pressure is unaffected by the operation of the gas
ballast. The vacuum is maintained in the system by closing the pump inlet valve.
For more information about the use of gas-ballast, refer to Section 3.10 and 4.1.
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