JOHNSON CONTROLS
7
FORM 160.43-NM4
ISSUE DATE: 11/12/2012
1
SECTION 1 - GENERAL
APPLICATION
Low Pressure Cutout (LPCO) controls 025 45742 set
point and deadband settings are factory set for R-11 or
R-123 duty application as:
P/N
DESCRIPTION
025 45742 002 CONTROL VACUUM SWITCH R-11 LPCO
Use with R-11 refrigerant
025 45742 003 CONTROL VACUUM SWITCH R-123 LPCO
Use with R-123 refrigerant
LPCO controls
025 45742
are available as retrofit
kits, inclusive of installation hardware, for converting
from the obsolete
225 15443 002
LPCO control used
in Model OT/HT Style “B” and “C” chillers having
Electronic Control Centers 366 70488, 366 70487, 366
73582, as:
P/N
DESCRIPTION
325 45742 602 KIT, CONTROL LPCO R-11
VACUUM SWITCH Use with
R-11 refrigerant
325 45742 603 KIT, CONTROL LPCO R-123
VACUUM SWITCH Use with
R-123 refrigerant
OPERATION
The Low Pressure cutout (LPCO) controls 025 45742
are actuated by evaporator pressure. The LPCO control
operates to stop the chiller compressor operation on the
decrease of the evaporator pressure equivalent to a re-
frigerant temperature of 28° F and permits re-starting,
(via the start button) when the evaporator pressure in-
creases equivalent to a refrigerant temperature greater
than 40° F.
LPCO controls 025 45742 set point and deadband set-
tings are factory set for R-11 or R-123 duty applica-
tion. The cutout set point and deadband settings are
field adjustable as described in section III Testing and
Adjustments.
LPCO controls 025 45742 are vacuum switches which
are negative gauge pressure controls that operate at a
predetermined constant pressure below atmospheric.
This means that the absolute pressure of the cutout set-
ting will vary with local atmospheric pressure changes.
LPCO controls 025 45742 require cutout setpoint and
Before installing, the installation and
maintenance instructions provided with
unit must be read and understood.
Before installing, verify the control part
no. matches the refrigerant duty applica-
tion.
For all applications, a factory set safety
control should be tested before use.
To avoid damaging control, proof pressure
and maximum temperature limits stated in
literature and on nameplates must never
be exceeded, even by surges in the system.
Operation of the unit up to maximum
pressure or temperature is acceptable on
a limited basis (e.g., start-up, testing) but
continuous operation must be restricted to
the designated adjustable range. Excessive
cycling at maximum pressure or tempera-
ture limits could reduce sensor life.
Vacuum switches are negative gauge
pressure controls that operate at a pre-
determined constant pressure below at-
mospheric. This means that the absolute
pressure of the cutout setting will vary
with local atmospheric pressure changes.
Vacuum switches require settings verifica
-
tion at installation and require recalibra-
tion if installed elevation is 300 feet or
more above or below sea level.
Preventative maintenance and periodic
testing is necessary for critical applica-
tions where damage could endanger
property or personnel.
These products do not have any field re
-
placeable parts.