Flow and Pressure Optimization and Control Depends on Response Time

“Autotuning” or automatic response time optimization, for control devices can quickly establish excellent flow control in a new or recently changed process.

A flow or pressure control device must be able to sense changes within a process and respond quickly enough to mitigate them. A flow device’s “response time” can be defined in various ways. A common definition of the control response time, as the “dead time” (the duration between the setpoint request and when the device begins to respond) plus the “time constant” (the time required for the device to move 63.2% from the initial value to the new value).

A device with a faster response time will correct disturbances more quickly and will track setpoint changes more closely. The figure below illustrates how various control devices might respond to a pressure wave moving through a system. The initial effect of the disturbance is the same for all four control devices; however, the device with a faster response time (blue) minimizes the effect of the disturbance and returns the flow to the setpoint more quickly.

Optimization can improve flow control performance when:

• the device is installed in a new system
• the system properties change (e.g., a significant change in pressure or a different process gas)
• system plumbing is significantly changed
• a control device is moved between systems or experiments
• an exact response is required
• multiple devices need to provide the same response
• the process requires faster or more precise control

Learn how to optimize your control response with Autotune with this knowledge base article on response time optimization.

Control device optimization can provide the best response for a particular process and environment. Automated optimization, such as Alicat’s Autotune function, makes it possible to measure current performance and improve it, without requiring extensive knowledge of control systems and parameters. Advanced functions such as autotuning enable a broader range of process engineers and technicians to achieve excellent flow control, even if the process or environment changes dramatically. As featured in Automation.com’s article.