CONTROL SYSTEMS FOR SURGE TANKS
Many surge tanks are supplied with a control system to manage the air/gas cushion in the tank and ensure that it is maintained correctly to provide adequate compression and expansion as will have been determined to be necessary to protect the pumped main from excessive high and low pressures.
The control system will be constructed in such a way that it will manage and correct for absorption of the air/gas cushion by the liquid in the tank, which will tend to cause the liquid level to rise, and out gassing from the liquid in the tank which will tend to cause the liquid level in the tank to fall.
All control systems commonly have the following components
A liquid level detection system
This will commonly be by way of a bypass level gauge with a with a float directly determining the level, an ultrasonic or radar
level gauge detecting the level or by inference through the use of
differential pressure gauges.
A venting system
All surge tanks which have their liquid level controlled require a
venting arrangement to enable the air/gas cushion to be vented to
atmosphere so that the liquid level may be adjusted in accordance
with the requirement of the requirements for the surge tank.
A control panel
Commonly a local control panel is required to house the switchgear
and control logic hardware, which may be PLC or relay logic based,
which will be arranged to carry out the control actions to either add
or vent the air/gas from the surge tank depending upon the
requirements for the surge system.
An air/gas addition system
All surge tanks which have their liquid level controlled require an
air/gas addition system to enable the air/gas cushion to be added
to so that the liquid level may be adjusted in accordance with the
requirement of the requirements for the surge tank.
Control systems are usually arranged to to provide one of the following control philosophies;
Fixed level
P-V
Variable level
Mass Control
Our page surge tank options explains these different choices
Contact us now with your requirements.
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