How to use setpoint ramping

Using setpoint ramping

Alicat controllers come equipped with a setpoint ramping feature that allows you to ramp up and/or down to changes in setpoint.

Setpoint ramping is one of Alicat’s latest mainline functions. With setpoint ramping you can set a maximum speed at which a mass flow or pressure controller flows until the setpoint is achieved. Typically, ramps have been programmed through PLCs (programmable logic controllers), but Alicat has simplified this process by allowing you to perform this functionality through the front display or via serial command. And the setpoint is updated every millisecond so you never lose the speed you’ve come to associate with Alicat.

Setpoint ramping is a utility that can be used in many fashions. One of our customer’s more common usages for this feature is for safety or precautionary. Rather than allowing a volume to be instantaneously pressurized or a high flow rate to be immediately seen by a process, ramping allows for a more controlled, observable behavior. Setpoint ramping can also be configured to only be applied to a single direction which is useful in situations in which you may need to quickly zero pressure or flow during an emergency.

To enable and edit the setpoint ramp functionality on your device, follow the instructions below.

Video

 

Step-by-Step Instructions

  1. Press the bottom right button for “MENU” selection.
  2. Press the top left button for “CONTROL” selection.
  3. Press the top left button for “SETPT RAMP” selection.
  4. Press the top left button for “DELTA” selection.
  5. Use the up, down, and select digit buttons to set your desired delta.
  6. Press the bottom right button for “SET” selection.
  7. Press the top right button for “TIME” selection.
  8. Use the up, down, and select digit buttons to set your desired time.
  9. Press the bottom right button for “SET” selection.
  10. Press the top middle button for “TIME UNITS” selection.
  11. Use the up and down buttons to select your desired time units.
    1. Note:  This will NOT change the rate, and it will automatically update the current rate to the newly selected units.
  12. Press the bottom right button for “SET” selection.

“My name is Marina Palese, and I’m an App Engineer at Alicat Scientific.  Today I’m going to show you how to set up setpoint ramping.  Let’s get started.”

To give a setpoint ramp to your device, we’re going to to MENU (bottom right button), CONTROL (top left button), SETPT Ramp (top left button), and from here we can set our DELTA (top left button).  This is how much we want the flow to change in this ramp, and we can set that to whatever value we like (ex. 100 SLPM).

At this point the display will read “Current Max Ramp Rate -None- SLPM/s”.

The TIME (top right button) will be the amount of delta over time.  Let’s say we want to change 100 SLPM per one second.

At this point the display will read “Current Max Ramp Rate 99.99999 SLPM/s”.

And then we can set out units (top middle button).  Let’s say we change these to hours.  Then, the current ramp rate will automatically adjust to whatever the time unit is.

Finally, the display will read “Current Max Ramp Rate 360000 SLPM/hour”.