Level Controllers

SOR Liquid Level Controllers monitor liquid levels in vessels and send a pneumatic signal to a local control system or directly to a Control Valve. Liquid Level Controllers are ideal for interface measurements, making them an excellent choice for measuring the level on gas separators and scrubbers. The reliability of the SOR design makes it well suited for liquid level applications in natural gas production, compression, and processing.

SOR recognizes that there is no industry convention with respect to terminology and definitions pertinent to Liquid Level Controllers. This glossary applies to SOR Liquid Level Controllers.

Controller Action – The Controller Action is determined by the orientation of the flapper bar. When the flapper bar pivot point is on the same side as the spring, the controller action is “Direct Acting”.  When the flapper bar pivot point is on the opposite side as the spring, it is a “Reverse Acting” controller. A “Direct Acting” controller will increase the output signal as the liquid rises.  For a “Reverse Acting” controller, the output signal will decrease as the pressure rises.  

Displacer Arm – The displacer arm connects the displacer to the torque arm.  A longer arm may be required to ensure the displacer is not obstructed by the wall of the tank, however a longer displacer will require a higher counteracting spring force.

Horizontal Displacer – For small tank applications, the displacer can be inserted horizontally to insure no obstruction by the tank wall.  This will limit the allowable proportional band however.

Mounting – The mounting of the Liquid Level Controller is determined by the orientation of the body and displacer arm.  While facing the front of the controller case, the side that body and displacer arm are oriented determines the mounting style.  If the displacer is on the right side of the controller case while facing the front of the controller, then it is considered “right-hand”.  If the displacer is on the left side of the controller case while facing the front of the controller, then it is considered “lefthand”.  The mounting configuration can be easily changed out in the field.  

Pilot – The valve that controls the flow of pneumatic air based on the position of the displacer.

Proportional Band – The Proportional Band is referred to as the percentage of the displacer that is used to actuate the level controller.  For example, if 9 inches of change in level will actuate the level controller and a 12” long displacer is used, then the level controller will have a 75% proportional band.  To adjust the proportional band, slide the fulcrum on the flapper bar along the sensitivity scale.  To decrease the proportional band, increase the sensitivity.  To increase the proportional band, decrease the sensitivity.

Sealed/Standard Case – The sealed case offers a weather tight housing as well as a manifold pilot assembly. The standard case does not include a cover gasket.

Sensitivity Fulcrum – The sensitivity fulcrum directly transfers the torque force applied by the displacer towards the pilot. 

Spring – The spring in the level controller applies a counter balance force to the weight of the displacer.  The more compressed the spring, essentially the lighter the displacer becomes.

Supply/Output Gauges – These gauges will show the pressure for the supply and output.  This will display when the valve is open and when the valve is closed.  If no pressure is showing on the output gauge, then the valve is closed.