Figure V.1
Liquid level control in a gas/liquid separator
2. The control times for operator invention recommended in this Appendix are the result of a compromise
between vessel size and operational robustness. If weight and space limitations are governing, e.g. in the
case of offshore applications, preference may be given to smaller holdups at the cost of shorter control
times.
3. The fail-safe direction is different for the high and low level trip, which is usually a reason to split up the
high and low level trip range and use two transmitters. If there is only one trip range it is preferred to make
this identical to the control range. This makes it easier to compare measurements, and allows dual use in
the event of instrument failure.