Setting control deadband

Setting control deadband

Control stability in closed volume systems is essential in many applications including cell research and fuel cell testing. Managing oscillation loops in dual valve systems is a critical part of enabling precision control of these systems.  This led us to develop our controller deadband functionality.

Balancing the operation of an inlet valve and an exhaust valve allows the PCD series to perform precise and extremely fast closed system pressure control, while minimizing the waste of potentially expensive gases.  At the core of our ability to do this is a well-balanced PD2I algorithm.  But when changing conditions, like ambient temperature, affect the system, active control can over compensate and cause oscillation loops.

Controller deadband functionality on our dual valve control systems allow users to create a +/- band of change around their chosen setpoint.  So once a system has successfully attained setpoint, if ambient conditions cause slight variances to the held value, the controller will not respond with a valve change, until the user defined “deadband” around the controller is exceeded.  Adding a depth of stable control to an already fast and dynamic control algorithm.

With these improvements our dual valve pressure controllers still provide the same speed you’ve come to know from our mass flow controllers with the added benefit of maintaining stability in fluctuating systems.

The following instructions show how to set control deadband.



Step-by-Step Instructions

1. Press The bottom right hand button on the main screen for the “MENU”.
2. Press the top left hand button for the “CONTROL” selection.
3. Press the bottom middle button for “CONTROL OPTS” selection.
4. Press the bottom middle button for “ADV CONTROL” selection.
5. Press the top middle button for “DEAD BAND” selection.
6. Use the select digit and the up and down buttons to set your desired range of setpoint deadband.
7. Press the bottom right hand button for “SET” Selection.
8. Your control deadband setting has been applied to your controller.


“Hello, my name is Michael Whiteside, I am an applications engineer here at Alicat Scientific. In this video, I am going to show you how to set up a control deadband on your Alicat device. Now let’s get started.  

In order to establish a control deadband on your Alicat device, we will hit menu (bottom right button), control (top left button), advanced control (bottom middle button), control options (bottom middle button), and deadband at the top here (top middle button).  

Now what this deadband functionality does is it tells the device not to change its valve position if the flowrate is within the deadband of the setpoint. If we give a 1 SLPM deadband, that means if the flowrate is within 1 SLPM of the setpoint, the device will not adjust its valve.  

That is how to establish a control deadband.”