White Rodgers 770-1 User Manual
- INSTRUCTIONS TYPE 770-1
AIR SWITCH
WHITE-RODGERS
With SPDT Switch Action
(Responds to Positive, Negative,
or Differential Pressure)
The Type 770-1 has a SPDT switch that can be actuated by a positive pressure,
negative pressure, or a differential of pressure. These two features, plus its
field adjustable "operating range", give this control unmatched versatility on a
wide variety of applications, some of which are shown below.
TYPICAL APPLICATIONS
POWER HUMIDIFIERS
Switch permits unit to operate
whenever there is proper air move
ment.
ELECTRONIC AIR CLEANERS
Switch permits power to cleaner
whenever blower of system is oper
0
ating.
NATURAL DRAFT BOILERS
Switch signals insufficient draft,
provides safety limit to stop firing
on lack of draft, starts again on
sufficient draft.
REFRIGERATION EQUIPMENT
-0
INDUCED DRAFT BOILERS
Proves operation of I.D. fan by
sampling draft or air flow.
Shuts off firing equipment on fan
-
failure.
DUCT STRIP HEATERS
Switch proves air movement across
heaters by positive pressure in front
of heater. Turns off heater to pre
vent burn-out on insufficient air
flow.
PROCESS DRYING
Switch monitors negative pressure
to stop conveyor or process, and
provides alarm signal on fan failure.
Ideal for bulk chemicals, food
processing, grain drying.
Switch responds to pressure drop
across refrigeration coils to signal
alarm condition or automatically ini
tiate or terminate defrost cycle.
GAS-FIRED UNITS
Switch proves sufficient air flow be
fore permitting gas valve to open
and ignition to occur.
FORCED DRAFT BOILERS
Proves operation of blower by
sampling positive or negative pres
sures for firing control and safety.
LEGEND
Negative Pressure
Positive Pressure
Pressure Differential
Pressure Sample Line
ELECTRICAL RATING
15 AMP 125/250/277 VAC NT.
1/4 HP 125 VAC.
1/2 HP 250 VAC.
ELECTRICAL SWITCH
Single pole, double
throw snap action switch
CONTROL SET POINT
Adjustable
WHITE-RODGERS DIVISION
EMERSON ELECTRIC CO.
9797 REAVIS ROAD
IsMIERSaN ®
ST. LOUIS, MISSOURI 63123
-SPECIFICATIONS-
FIELD ADJUSTABLE
On pressure rise at .05
to 12" w.c.
CONDUIT OPENING
7/8" diameter opening
accepts 1/2" conduit
RECOMMENDED OPERATING POSITION
Diaphragm vertical
Printed in U.S.A.
OPERATING TEMPERATURE RANGE
-40 to 180° F.
SAMPLE LINE CONNECTORS
Male externally threaded 7/16"-24
UNS 2 A thread complete with nut
and self aligning ferrule.
SAMPLE LINE CONNECTIONS
Connectors will accept 1/4" O.D.
rigid or semi rigid tubing. Slip
on tubing adaptors optional.
PART No. 37-4898A
Replaces 37-4395
9110
4324
Rev.B
MOUNTING INSTRUCTIONS
_0_
^9=
The Air Switch must be mounted to a vertical surface, as shown in above draw
ings to assure that diaphragm will be in a vertical plane.
H
3
SEE BACK PAGE FOR MOUNTING DIMENSIONS.
WIRING
All wiring should be done according to local and national electrical codes and ordinances.
Fig. 1 - SPOT Switch of Type 770-1.
The SPDT switch can be actuated by a positive or negative pressure, or by a
differential of pressure. This control is ideally suited for residential applica
tions such as Electronic Air Cleaners and Humidifiers, but it is equally well
suited for commercial installations, including applications where alarm circuits
(Without pressure applied to
diaphragm, switch contacts
are In position shown.)
Fig. 2 - Typical Air Cleaner Installation.
are required.
Fig. 3 - Typical Humidifer Installation.
IsJ
AIR SWITCH
SAMPLE LINE CONNECTIONS •
r+
O
L
POSITWE ONLY
LOWER NEGATIVE
HIGHER POSrrrv'L
SEE NEXT PAGE FOR LOCATION OF SAMPLE LINES.
NEGATIVE ONLY
HIGHER NEGATIVE
LOWER POSITIVE
E F
NEUTRAL
HOT
Male externally threaded with nut and
self-aligning ferrule.
POSITIVE PRESSURE ONLY:
Connect sample line to E; F remains open to
atmosphere.
NEGATIVE PRESSURE ONLY;
Connect sample line to F; E remains open to
atmosphere.
TWO NEGATIVE SAMPLES:
Connect highest negative sample to F; lower
sample to E.
TWO POSITIVE SAMPLES:
Connect highest positive sample to E; lower
sample to F.
ONE POSITIVE AND ONE NEGATIVE:
Connect positive sample to E; connect n^a-
tive sample to F.
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