APPLICATION
For low pressure or vacuum- to “make” or “break” electrical circuits on
small changes in the differential between two pressures. Examples: to
indicate a change in resistance through a filter; to indicate a change in
differential due to a change in air flow conditions; to indicate interruption
of air flow.
These controls incorporate two pressure chambers separated by a sen-
sitive diaphragm. Each pressure chamber is connected to a separate
pressure source and the control is set to operate as the relationship of
the two pressures change.
The operating difference required to operate the switch is adjustable
within the limits shown in the table. The switch operating range is obtain-
able throughout the control range. The change in pressure difference
required to restore the switch to its original position is not adjustable -
this reset value is the fixed sensitivity. Once the operating pressure dif-
ference has been established, it will remain constant over the control
range.
SINGLE STAGE OPERATION
Differential Pressure Controls Types PPQ, PPQW and PPQE (with suf-
fix -2 or -3) are single contact mercury switch equipped controls provid-
ing single stage operation for single pole, single throw make and break.
TWO-STAGE OPERATION
Types PPQ, PPQW and PPQE with suffixes -4122, -4123, -4129 or -
4132, incorporate two SP-ST mercury switches and provide two-stage
operation, that is, for operating one contact at a value different than that
operating the other contact.
LOCATION
Mercoid
®
Differential pressure controls are extremely sensitive to small
pressure changes and, therefore, require special consideration to avoid
mechanical vibration and pressure pulsations. They must be secured
firmly in a level position on a panel or even wall surface which is free
from vibration.
SPECIFICATIONS
Temperature Limits:
-10°F to 180°F (-23°C to 82°C).
Pressure Connections:
(2)
1
/
8
″ NPT(F).
Electrical Rating:
0.3A @ 115 VAC, 0.15A @ 230 VAC,
0.9A @ 24 VAC, 0.15A @ 115 VDC, 0.07A @ 230 VDC.
Conduit Opening:
7
/
8
″ hole for
1
/
2
″ HUB.
Switch Type:
Mercury.
Wiring Connections:
Screw type.
Setpoint Adjustment:
Screw type, internal.
Housing
: Painted steel STD or W, aluminum E type.
Wetted Parts:
Nylon reinforced Buna-N, steel, brass, aluminum.
Weight:
PPQ 4
1
/
2
lbs. (2 kg); PPQW 5
1
/
2
lbs. (2.5 kg); PPQE 25 lbs. (11
kg)
Installation:
Vertical, in a vibration free area.
Types PPQ
(general purpose) controls. Place the
1
/
8
″ pressure connec-
tion at the bottom so that the conduit connection is to the left. Use the
mounting studs and do not attempt to support the control solely by the
pressure connection. To level sight across the two cover screws to be
sure control is lined up horizontally.
Types PPQW
(weather-resistant) controls. Use the mounting studs and
do not attempt to support control solely by the pressure connection. Be
sure pipe connection is in a vertical position. After cover is securely
attached with name plate on bottom of cover, sight across the lower end
of nameplate to see that control is lined up vertically.
Types PPQE
(explosion proof). Mount controls by means of mounting
lugs attached to control housing. Line up horizontally by sighting across
the left and right conduit hubs.
Series PPQ Differential Pressure Controls
Specifications - Installation and Operating Instructions
Bulletin IN-563
MERCOID DIVISION
Phone: 219/879-8000
www.dwyer-inst.com
DWYER INSTRUMENTS, INC.
Fax: 219/872-9057
e-mail: [email protected]
P.O. BOX 258 • MICHIGAN CITY, INDIANA 46361, U.S.A.
7/8 [22.2] DIA.
CONDUIT
OPENING
13/64 [5.2]
3 PLCS AT
120
°
ON A
6-1/2 [165.1]
DIA. CIRCLE
7
[177.8]
DIA.
5-3/4
[146.1]
DIA.
1/8 NPT
2 PLCS.
3-9/16
[90.5]
13/16
[20.6]
7/16 [11.1]
2-7/16
[61.9]
10-13/16
[274.6]
7/16 [11.1]
DIA. TYP.
CONDUIT
HUB
3/4 NPT
3 PLCS.
5/8 [15.9]
2-13/16
[71.4]
1/4 NPT
7-5/8
[193.7]
SQ.
10-11/16
[271.5]
6-9/16
[166.7]
7/8 [22.2] DIA.
CONDUIT OPENING
13/64 [5.2] DIA.
3 PLCS AT 120
°
ON A 6-1/2 [165.1]
DIA.CIRCLE
7
[177.8]
DIA.
4-1/4
[108]
1/8 NPT
2 PLCS.
2-7/16
[61.9]
13/16 [20.6]
7/16 [11.1]
Weather Resistant
Explosion-proof
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