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.
