Dwyer 1996 - Manual

Series 1996 Gas Pressure Switches are
reliable and convenient switches for gas-fired furnaces
and equipment using natural, manufactured or LP gas.
Both models (Model 1996-5, with a pressure range of 1.4
to 5.5
″ w.c.; Model 1996-20, with a pressure range of 4
to 20 ″ w.c.) feature visible set point and on-off
indicators.
OPERATION
Pressure acting on the power diaphragm rotates the
amplifying lever, which in turn extends the range spring
and rotates the snap switch input lever. When the set
point is reached, the snap switch is actuated and the
electrical contacts make or break. Decreasing pressure
after the switch has been actuated reverses the action,
de-actuating the switch and returning the contacts to
their normal position.
INSTALLATION
1. Select a location free from excessive vibration and
corrosive atmosphere. These switches may be used in
ambient temperatures as low as - 30°F ( - 34°C) and as
high as 110°F (43°C).
2. Mount switch with diaphragm in a horizontal position
and gas pressure connection at bottom. Connect the
switch to the source of gas pressure using either the
NPT (F)8
″ or NPT (M) 4″ thread. Gas pressure connec-
tion should always be to bottom connection of switch—
see diagram above—which is equipped with a restrictor
orifice. Be sure to hold or turn switch with a wrench on
the hex portion of the bottom connection. This will pre-
vent applying excessive torque to the bottom fitting,
which could damage the switch.
The port identified with the letters LO-PR is used as a
vent in fuel gas switches and should be vented to
outside atmosphere or the combustion chamber in
accordance with the furnace manufacturer’s
instructions. The port identified by the letters HI-PR is
not used in fuel gas switches and is neither tapped nor
connected to the diaphragm chamber.
Series 1996 – Natural and L.P. Gas Pressure Switches
Specifications - Installation and Operating Instructions
Bulletin E-58
DWYER INSTRUMENTS, INC.
Phone: 219/879-8000 www.dwyer-inst.com
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: 219/872-9057 e-mail: [email protected]
Lit-By Fax: 888/891-4963
Series 1996 Gas Pressure Switches
are designed for use with natural, man-
ufactured or LP gas or air. Note set point adjustment indicator win-
dow. For quick adjustment of set point
before/after installation, turn adjustment
screw until red bar is at desired set point.
To adjust for low gas pressure interlock
service, refer to chart (other side). Connections, dimensions and visible
on-off indicator: Model 1996-20 and
Model 1996-5 Gas Pressure Switches.
PHYSICAL DATA
Temperature limits: 32°F/0°C (- 30°F/- 34.4°C for dry gas or
air) to 110°F/ 43.3°C
Pressure connection:
8″
NPT (F) or
4″
NPT (M)
Vent connection:
8″
NPT
Electrical rating: 15 amps, 120-480 volts, 60 Hz. A.C.
Resistive
8″
H. P. @ 125 volts,
4″
H. P. @ 250 volts, 60 Hz.
A.C.
Wiring connections: 3-screw type, Common, Normally Open
and Normally Closed
Set point adjustment: Screw type with visible indicator,
inside cabinet enclosure
On-off indicator: In window, on exterior of conduit enclosure.
Shows at a glance whether pressure is above or below set
and reset points.
Housing: Aluminum die casting and steel stamping,
zinc-plated for 200 hour salt spray resistance
Diaphragm: Molded Buna-N
Calibration spring: Stainless Steel
Weight: 1 lb, 2 oz
U.L. and C.S.A. listed, F.M. approved
3-1/8
[79.38]
3-1/2
[88.90]
1/8 (F) GAS
PRESSURE CONNECTION
1/4 NPT EXTERNAL THREAD
(ALTERNATE GAS CONNECTION)
VENT CONNECTION
ON OPPOSITE SIDE
WINDOW AND VISIBLE
ON-OFF INDICATOR
7/8 [22.23] OPENING FOR
1/2 [12.7] CONDUIT CONNECTION
REMOVABLE CONDUIT
ENCLOSURE COVER
WARNING:
Do not connect fuel gas to LO-PR port.
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