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PSW400
Pressure Switches
INSTRUCTION
SHEET
M0534/0902
INSTALLATION INSTRUCTIONS FOR OMEGA
®
SERIES PSW400 PRESSURE SWITCHES
The OMEGA
®
PSW400 Series pressure
control is a precision device which fea-
tures a snap-action switch. Fixed dead-
band is available with dual SPDT indepen-
dently adjustable switches with various
electrical ratings. Adjustable deadband is
available with various electrical rating.
The PSW400 Series snap-action pressure
switch offers a NEMA 7/9 explosion-proof
enclosure, Class I, Div. 1 & 2, Groups B, C
& D and Class II, Div. 1 & 2, Groups E, F
& G. The enclosure is an epoxy-coated
aluminum casting.
INSTALLATION
This control is a precision instrument and
should never be left with internal compo-
nents exposed. During installation, insure
that covers are in place and conduit open-
ings are sealed.
MOUNTING
Four holes in the bracket supplied are used
in surface mounting of the control. Loca-
tion of these holes is shown on the general
dimension drawings. Mount on a vibration-
free surface or pipe. When tightening con-
trol to pressure line, always use the
wrench flats or hex on the pressure connec-
tion. Never tighten by twisting the case.
ELECTRICAL CONNECTION
Remove top cover; the cover unscrews
CCW. Wire directly to the switch according
to circuit requirements.
CONDUIT CONNECTIONS
Two
3
⁄
4˝ NPT holes are provided, one fitted
with a plug., the other with a cap. It is rec-
ommended that Teflon tape or other sealant
be used on conduit bushing or plug threads
to ensure integrity of the enclosure.
SETPOINT ADJUSTMENTS
Dual Setpoint Switch
Remove front cover, which is held in place
by two screws. There are two range adjust-
ing wheels. The adjusting wheel on the left
(labeled A) controls the left switch, the
adjusting wheel on the right (labeled B)
controls the right switch. The switches are
set independently.
Note:The units are calibrated at the factory
such that for proper operation, switch B
setpoint must be set higher than switch A
setpoint.
For setpoint adjustment to within ±1% of
nominal range, mount the switch on a cal-
ibration stand, and use a suitable refer-
ence such as an OMEGA process gauge
(Model PGH or PGJ), or test gauge (Model
PGT). Monitor switch with a suitable pilot
light or meter.
Pressurize the system to the required set-
point and turn the adjusting wheel until
the switch changes mode. When the set-
point has been achieved, raise and lower
the pressure to insure that the setpoint is
correct. This must be done for both set-
point A and setpoint B.
ADJUSTABLE DEADBAND SWITCH
Remove front cover, which is held in place
by two screws. The adjusting wheel
labeled A controls the reset point of the
switch. The adjusting wheel on labeled B
controls the setpoint of the switch.
Note:The units are calibrated at the factory
such that for proper operation, setpoint B
is always higher than reset point A .
For accurate setpoint adjustment, mount
the switch on a calibration stand, and use
a suitable reference such as an OMEGA
process gauge (Model PGH or PGJ), or test
gauge (Model PGT). Monitor switch with a
suitable pilot light or meter. Pressurize the
system to the required setpoint. Move
adjusting wheel on spring B until switch
changes mode. The lower pressure to the
reset point, move adjusting wheel on
spring A until the switch changes mode.
Raise and lower pressure to insure that
setpoint is correct. Repeat as necessary.
STANDARD RANGES
10, 30, 60, 100 & 150 IN.H
2
O
STANDARD RANGES – psi
0/15 0/30 0/100 0/400
0/20 0/60 0/200 0/600
3/4 NPT
TYP
Ø.31 (8)
4 HOLES
D
E
F
H
K
A
G
Clearance
Required for
Cover Removal
I
L
C
B
J
1/4 NPT
L
11
/16 (17)
3/4 NPT
TYP
B
Ø.31 (8)
4 HOLES
D
E
F
C
H
J
A
G
Clearance
Required for
Cover Removal
I
K
1/4 NPT FEMALE
11
/16 (17)
ABCDEFGHIJK
7
7
⁄16 53
7
⁄8 1
1
⁄16 2
5
⁄16 1
5
⁄16
11
⁄16 4
3
⁄4 5
1
⁄2 2
3
⁄4 2
5
⁄16
(189)(127) (98) (27) (59) (33) (17) (121)(140) (70) (59)
ABCDEFGHIJKL
8
1
⁄8 53
7
⁄8 1
1
⁄16 2
5
⁄16 2
11
⁄16 4
3
⁄4 5
1
⁄8 5
1
⁄2 2
3
⁄4 5
5
⁄16
(206) (127) (98) (27) (59) (51) (17) (121) (130) (140) (70) (135)
2
13
/16 (71)
Requires Standard
5
/16 (8) Dia. U-Bolt
Not Furnished
Ø.38 (10)
U-Bolt Holes
2
13
/16 (71)
2
7
/32 (56)
PIPE MOUNTING
BRACKET
PSW400 – H
2
O PSW400 – psi
PSW400 – Pipe Mounting Bracket
M0534 8/99 DPS-5C-1P-10/99 Printed in U.S.A.