JOHNSON CONTROLS
13
FORM 160.43-NM4
ISSUE DATE: 11/12/2012
3
TABLE 1 -
PRESSURE CONTROL SETTINGS
YORK PART NO.
CUTOUT SET POINT TO OPEN BETWEEN
DEADBAND SETTING
APPLICATION
025 41881 002
19.20 in. and 18.90 in. Hg. Vacuum
10.80 in. and 11.10 in. Hg. Absolute
4.00 in. Hg. ± 0.50
Use with R-11
025 41881 003
21.30 in. and 21.00 in. Hg. Vacuum
8.70 in. and 9.00 in. Hg. Absolute
4.00 in. Hg. ± 0.50
Use with R-123
SECTION 3 - TESTING AND ADJUSTMENTS
One Atmosphere equals:
ABSOLUTE
GAUGE
14.695 psia
=
0.00 psig
30.00 in. Hg. Absolute =
0.00 in. Hg. Vacuum
CUTOUT on pressure fall: refer to Table 1 for setpoint.
CUTIN on pressure rise: CUTIN equals CUTOUT plus
DEADBAND settings. Refer to Table 1 for settings.
SECURE CHILLER FROM OPERATION
1. Shut off power source feed to the chiller Electron-
ic Control Center (ECC).
2. Lock-Out, Tag-Out the chiller.
3. Pull ECC fuses 1FU, 2FU and 3FU to ensure the
LPCO control wiring is deenergized.
4. Close the evaporator service valve having gauge
piping going to the “Cooler” (evaporator) panel
gauge and LPCO control.
CONNECT LPCO PRESSURE CONNECTION
TO A CALIBRATED VACUUM SOURCE
1.
Disconnect the 1/4 in. flare nut on 90 deg. end
of capillary tube to the 1/4 in. external flare half
union fitting at the LPCO control pressure con
-
nection.
2. Using clean 1/4 in. refrigerant hoses, connect a
controllable vacuum source in series to a digital
vacuum gauge and to the 1/4 in. external flare half
union fitting at the LPCO control pressure con
-
nection. Apply tightening torque to the hose con-
nection only while holding back on fitting. Secure
hose connection to fitting tight enough to ensure
a leak free seal.
TOOLS NEEDED
•
Open-end wrenches; 3/4 in., 5/8 in., 9/16 in., 3/16
in. and 1/4 in.
•
Screwdrivers; Flat Blade and Phillips
•
Vacuum source; Controls Pump J/B P/N 40200
(500 psi 25 in. Hg. vac.) or equivalent.
•
Digital vacuum gauge; min. 2-digit (0.00) display,
capable of reading 1 ATMS to 30 in. Hg vacuum
with 1% accuracy or better.
Using the sensor housing or bracket to
tighten the fitting to the source will result
in damage to the switch.
For all applications, a factory set unit
should be tested before use.
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.
Always recheck settings after any adjust-
ments are made.
