Instrument Operation
3-7
D r a i n M o d e s
At any time during operation, a drain cycle can be initiated
manually by pressing the Drain/Prime button on the front panel
and then pressing it a second time and holding it for at least one
second. During a drain cycle, the pump will be turned off and a
drain valve will be opened allowing the reservoir to be drained. The
cycle duration is one minute, but it can be terminated early by
pressing the Display button on the front panel. The Drain
connector on the back panel is closed if disconnected. This avoids
spillage of water, but it will also keep the reservoir from draining if
nothing is connected to the Drain connector.
To select the recycle mode and the drain modes, press the
Drain/Prime button to access the Drain/Prime menu. Press the
button two more times to select the Set Drain Mode option. Press
and hold the button for at least a second to access the Set Drain
Mode menu. One of four drain modes can be selected through this
menu: Recycle/Manual, Recycle/Auto Drain, Auto Drain, and
Continuous Drain. These modes can also be selected through
firmware commands.
In Manual drain mode, the UWCPC will only perform a drain cycle
when initiated through the front panel Drain/Prime menu or by
command through a data port.
When operating in Automatic drain mode, the UWCPC will begin a
drain cycle when the level sensor detects that the reservoir is full.
During the Continuous drain mode, the drain value is left open and
water entering the reservoir immediately drains to the externally
connected Drain bottle. The Drain bottle must be tightly sealed and
vented to the Vent connector on the back panel.
For all drain modes it is important that the air pressure at the
Sample Inlet be equal or higher than the pressure at the drain
bottle. If the pressure at the Sample Inlet is lower than the drain
bottle, the reservoir will not drain into the bottle, but can
potentially flow up and out of the Sample Inlet. The sample pump is
turned off during the drain cycle to assist in ensuring that any
pressure at the inlet is minimized. In cases where the sample inlet
pressure is reduced by external sources, the second port on the
