Flow and Pressure Control
Turning gas flows on and off
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Turning gas flows on and off
All gas flows can be turned on or off from the keyboard without disturbing the
flow or pressure settings. However, the effect of an Off command depends on
whether the gas stream is EPC-controlled or not.
EPC-controlled streams
The valves in an EPC gas control module are designed for gas metering rather
than On/Off operation. When this type of valve is driven to the Off state, there
may still be a small flow, as much as 0.2 mL/min, through it. The display will
show this flow even though Off also appears. Note that this is an internal leak,
not a leak to the outside.
NonEPC-controlled streams
The valves in a nonEPC gas control module are designed only for On/Off action.
They are gas-tight when Off.
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