Hi! My name is Jeff Jennings. This video will demonstrate computer automation
of high vacuum in the range of 100 to 400 microns (.1 to .5 mbar absolute) using an
Equilibar vacuum regulator. This type of system is useful for chemical
processes such as vacuum distillation for analytical applications. Let’s first look at the system setup. We will start with the vacuum pump, such as
this 10 acfm oil piston pump. A stainless steel Equilibar EVR3 vacuum regulator
controls the vacuum process proportional to the vacuum pilot pressure on its dome. The pilot pressure is supplied by an Equilibar
QPV electronic pressure regulator, which receives a command from the computer and produces a
variable vacuum pressure to steer the Equilibar vacuum regulator to its setpoint. The customer’s process is simulated by this
stainless steel volume. A needle valve with a small rotameter allows
us to vary the mass flow going into the process. This rotameter is ranged zero to 50 standard
milliliters per minute. Both the process and pilot pressures are monitored
by absolute pressure sensors reading in micron. Now we’ve started the pump. We are monitoring and controlling the vacuum
process using LabVIEW with a simple PID loop. The controller watches the process pressure
sensor and adjusts the pilot pressure command as necessary to achieve the desired setpoint. The red line shows the desired setpoint for
the absolute pressure in microns. The white line shows the actual process pressure. The green line shows the pilot pressure applied
to the dome of the Equilibar vacuum regulator. Now we’re controlling at 400 micron with about
10 standard milliliters a minute mass flow. Let’s see the effect of changing the setpoint
from 400 to 600 micron. Note that the PID controller adjusts the green
pilot pressure to bring the white process pressure line back to the setpoint. Now let’s vary the mass flow coming into the
process. By increasing the mass flow from about 10
to about 14, you can see how the closed loop process responds to process variations. The PID adjusts the pilot pressure again to
keep the process under control. Now let’s explore the lower absolute pressures. We’re going to reduce the mass flow so that
our pump has capacity to go down to around 100. We’re going to change the setpoint from 600
to 150 microns. This closed loop control is capable of going
to even lower absolute pressures limited by the capacity of a given pump. For more information or to discuss your vacuum
automation application, contact us at equilibar.com.