APPENDIX G
TYPICAL LEVEL CONTROL APPLICATION
FOR PMC-1 ELECTRO-PNEUMATIC CONTROLLER
The Leslie PMC-1 electro-pneumatic controller provides an
accurate, economical alternative to conventional pneumatic
or electronic controllers. A standard differential pressure
transmitter is connected to the PMC-1 at the transmitter is
connected to the PMC-1 at the transmitter input terminals.
The PMC-1 provides 24VDC power to the dp transmitter,
compares the 4-20mA signal returned to the set point and,
using a series of short pneumatic pulses, modulates the
control valve as required to maintain the desired level. The
PMC-1’s slow loop control mode can be selected for
enhanced control in systems that respond slowly to control
valve changes.
In a closed system, the differential pressure transmitter is
piped as shown above. The upper sensing line measures the
static pressure in the system and acts as a reference point.
the difference between the upper and lower sensing lines is
the head pressure of the liquid. In an open system, the
reference line is vented to atmosphere. A three-valve
manifold is recommended for use with the dp transmitter to
facilitate isolation of the transmitter for replacement or in-
line calibration.
During installation, the PMC-1 is calibrated by dialing in the
upper and lower limits of the differential pressure
transmitter. The set point and process status can then be
read directly from the backlit LCD display in the units of
measurement preferred by the user.
When ordering a dp transmitter for use in a liquid level
application, it is important to specify the range (high/low
level limits) and the suppression (“WC” in reference line).
PMC-1
Up to 100 psi
Plant air
Airset
4-20mA
24VDC
DP transmitter with
3-valve manifold
26/2.5.1Rev.3-0103
12501 Telecom Drive, Tampa, FL 33637
Ph: (813) 978-1000 • Fax: (813) 978-0984
w w w . l e s l i e c o n t r o l s . c o m
