Help. I can't get at my air regulator!

In an earlier article in this e-zine I wrote about "Whyto allow the operator to adjust the downstream air
use a regulator?". In this installment, the questionpressure to the correct level for that application.
posed is what do you do when you can't get at yourAn I/P controlled regulator is another option. This
pressure regulator due to it's location?type of electronic regulator will adjust the
You can control a remote compressed air regulatordownstream pressure depending on the current that
electrically or you can control the remote regulatoris being sent to it by the programmable logic
with an air signal, therefore, wherever the regulator iscontroller on the machine. A 4 milliamp signal might
on the machine or in the building, it can be controlledcorrespond to 0 PSI downstream pressure and 20
from afar by an operator or a programmable logicmilliamps might equal 100 PSI downstream pressure.
device.A current somewhere between would adjust the
With an air piloted regulator a small "pilot" air regulatorpressure accordingly. If the regulator was being sent
is installed in an accessible location. It's output signal is12 milliamps, then the corresponding downstream
plumbed to the air-in signal port usually on the top ofpressure might be 50 PSI, for example.
the remote 'main' air regulator. As the pressure fromAs the application either demanded an increased or
the pilot regulator is adjusted this will increase orreduced pressure, a pressure sensing device at the
reduce the downstream air pressure emanating fromapplication would read the pressure and provide the
the remote main unit by increasing or decreasing thecontroller with the pressure information. If a change
pressure on the internal diaphragm, much as if anin air pressure was necessary the PLC would adjust
operator were turning the adjusting screw.the current to the I/P regulator to effect change,
A 50 PSI air pilot pressure may product auntil the pressure sensor signaled the controller that
corresponding 50 PSI output on the main regulator.the pressure level was now within the programmed
Correlation between the pilot and the main airpressure range.
regulator isn't really necessary, however. If a small airAn electronic E/P regulator works in a similar fashion
line is plumbed from a 'T' in the downstream line ofto the I/P type, but the E/P style works on voltage.
the main regulator and run to a visible remote airA 0 Volt signal might represent 0 PSI downstream
pressure gauge located near the pilot regulator, bypressure, while a 10 Volt signal might represent 100
monitoring that remote gauge, the operator canPSI. As the application demanded greater or less
adjust the pressure to the main regulator as neededpressure a sensing device would send the pressure
to "dial in" the downstream pressure that is requiredlevel to the controller which would increase or
for the application.decrease the voltage to the unit, thereby adjusting
Another benefit of the air piloted regulator it that itdownstream pressure.
can be adjusted remotely and safely for operation inCompressed air regulators usually work best when
explosive for flammable locations since air pilotedthey are installed close to the application for which
regulators - unlike their electrical cousins - do notthey are controlling the pressure. Sometimes that
generate a spark when they function.means that they are located inaccessibly, or even in
Some electric regulators may contain a simple electricanother building from the operator interface or
motor that, when activated by an operator, willcontrol center. Air piloted and electric air regulators
adjust the regulator to increase or decrease theallow the optimal location for the main regulator, and
downstream pressure. A remote air gauge plumbedprovide convenience for the human or computer
from the downstream side of the remote unit, wouldoperator that has to control them from afar.
be useful in providing pressure feedback information