Dwyer Instruments Series 1900 Pressure Switch Installation and Operating Instructions
Series 1900 Pressure Switch
POWER INPUT
TERMINALS
+ –
GROUNDING
SCREW
®
Specications - Installation and Operating Instructions
1/8 FEMALE NPT
HIGH PRESSURE
CONNECTION
3
41/64
[16.27]
1-19/32
[40.48]
2-11/32 [59.53]
1-3/4 [44.45]
CLEARANCE
FOR
COVER REMOVAL
[76.20]
ø 7/8 [22.23]
CONDUIT
CONNECTION
ø 3-1/2
[88.90]
1-5/16
[33.32]
TYP
51/64
[20.24]
1-7/8
[47.63]
2-9/32 [57.94]
2-7/16 [61.90]
Bulletin E-56
60° TYP
(2) ø 3/16 [4.76]
MOUNTING
HOLES ON
A 4-3/16
[106.36] B.C.
1/8 FEMALE
NPT LOW
PRESSURE
CONNECTION
Series 1910 pressure switch. All
pressure and electrical connections
and set point adjustments are on one
side for easy installation.
Advanced design and precision construction permit these switches to perform many
of the tasks of larger, costlier units. Designed for air conditioning service, they also
serve many uidics, refrigeration, oven and dryer applications. For use with air and
non-combustible gases. Series 1900 Pressure Switches are available with set points
of 0.07 to 20 inches water column. Set point adjustment can be made easily - before or
after installation. Range screw is inside conduit enclosure to help prevent tampering.
For easy mounting and access, pressure and electrical connections and set point
adjustment are located on one side. This permits installation in corners or spaces too
small for other switches.
SPECIAL MODELS & ACCESSORIES
Special close coupled street elbow for right angle pressure connections. Can be
installed on switch anytime. Zinc plated aluminum.
5-7/16 [138.1]
4-3/4 [120.7]
4 [101.6]
7/8 [22.22]
Ø5/16
[Ø7.938]
3/4 [19.05]
HIGH PRESSURE
CONNECTION 1/8 N.P.T.
Weatherproof Housing
16 ga. steel enclosure with gasketed cover (NEMA 4) for wet or oily conditions.
Withstands 200 hour salt spray test. Wt. 5 Ibs. (2.3 kg). Switch must be factory installed.
Change 1910 base number to 1911 and add -WP sufx. Example: 1911-1-WP.
4X Ø.281
[7.14]
1/8 FEMALE
NPT HIGH PRESSURE
CONNECTION
LOW PRESSURE
CONNECTION 1/8 N.P.T.
2X 6-1/8
[155.58]
2X 4-1/4
[107.95]
1/8 FEMALE NPT
LOW PRESSURE
CONNECTION
Series 1910 switch with conduit
enclosure off. Shows electric switch
and set point adjustment screw.
1/2 NPT WEATHERPROOF
ELECTRICAL CONNECTION
3 [76.20]2 [50.80]
3/4 [19.05]
1-1/4
[31.75]
6-1/2 [165.10]
CLEARANCE FOR
COVER REMOVAL
6-5/8
[168.28]
3 [76.20]
3-1/8
[79.38]
1/2 NPT
PROCESS CONNECTION
1-1/8 [28.58]
3/32
[2.381]
3X 1-1/16
[26.99]
3 [76.20]
The Dwyer-engineered force-motion amplier increases the leverage of
diaphragm movement and results in a switch with excellent sensitivity and
repeatability.
SPECIFICATIONS
Service: Air and non-combustible, compatible gases.
Environment: Standard model intended for indoor use.
Wetted Materials: Consult factory.
Temperature Limits: -30 to 180°F (-34 to 82.2°C) (32°F for non dry air).
Pressure Limits: 45 in w.c. (11.2 kPa) continuous, 10 psig (68.95 kPa) surge.
Humidity Limit: 80% RH (non-condensing).
Altitude Limit: 6560 ft (2000 m) max.
Switch Type: Single-pole double-throw (SPDT).
Repeatability: ±3%.
Electrical Rating: 15 A @ 120-480 VAC (~), 60 Hz. Resistive 1/8 HP @125
VAC(~), 1/4 HP @ 250 VAC(~), 60 Hz. Derate to 10 A for operation at high cycle
rates.
Electrical Connections: 3 screw type, common, normally open and normally
closed.
Installation Category: III (transient over-voltage).
Process Connections: 1/8˝ female NPT.
Mounting Orientation: Diaphragm in vertical position. Consult factory for other
position orientations.
Set Point Adjustment: Screw type inside conduit enclosure.
Pollution Degree: 2.
Weight: 1lb. 4.5 oz. (581 g).
Agency Approvals: CE, UL, CSA, FM.
EXPLANATION OF SYMBOLS
Symbol Publication Description
IEC 60417 - 5032
~
IEC 60417 - 5019
SERIES 1910 SWITCHES - MODELS OPERATING RANGES, DEADBANDS
Operating Range,
Model
in w.c.
1910-00
0.07 to 0.15
1910-0
0.15 to 0.5
1910-1
0.40 to 1.6
1910-5
1.40 to 5.5
1910-10
3.0 to 11.75
1910-20
4.0 to 20.0
Alternating current
Protective conductor terminal
Approximate Dead Band
At Min. Set Point At Max. Set Point
0.04
0.10
0.15
0.30
0.40
0.40
0.04
0.10
0.16
0.30
0.40
0.50
Explosion-Proof Housing
NEMA 7, 9 NEMA 3. (7 lbs). Switch must be factory installed. Change model to 1911
and add -EXPL sufx. Example: 1911-1-EXPL. Aluminum base and cover rated Class
I, Groups C & D, Div. 1. Class II, Groups E, F, & G, Div. 1.
DWYER INSTRUMENTS, INC.
INSTALLATION
1. Select a location that is free from excessive vibration, corrosive atmosphere and
where the ambient temperature is within the limits for these switches.
2. Mount standard switches with the diaphragm in a vertical plane and with switch
lettering and nameplate in an upright position. Some switches are position
sensitive and may not reset properly unless they are mounted with the diaphragm
vertical. (Special units can be furnished for other than vertical mounting
arrangements if required.)
3. Connect switch to source of pressure, vacuum or differential pressure. Metal tubing
with 1/4˝ O.D. is recommended, but any tubing which will not restrict the air ow
can be used. Connect to the two 1/8˝ female NPT pressure ports as noted below:
• Differential pressures - connect pipes or tubes from source of greater pressure
to high pressure port marked HI-PR and from source of lower pressure to low
pressure port marked LO-PR.
• Pressure only (above atmospheric) - connect tube from source of pressure to
high pressure port. The low pressure port is left open to atmosphere.
• Vacuum only (below atmospheric pressure) - connect tube from source of
vacuum to low pressure port. The high pressure port is left open to atmosphere.
CAUTION
4. Electrical connections to the standard single pole, double throw snap switch are
provided by means of screw terminals marked “common”, “norm open”, and “norm
closed”. The normally open contacts close and the normally closed contacts open
when pressure increases beyond the set point.
Power must be off while wiring connections are being made.
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 switcch is actuated and the electrical contacts make or break.
ADJUSTMENT
To change the set point, proceed as follows:
A. Remove the snap-on cover from the conduit enclosure by loosening its retaining
screw and pulling rmly at its bottom end. Turn the slotted adjustment screw at
the top of range spring housing clockwise to raise the set point pressure and
counter-clockwise to lower the set point.
B. The recommended procedure for calibrating or checking calibration is to use a
“T” assembly with three rubber tubing leads, all as short as possible and the
entire assembly offering minimum ow restriction. Run one lead to the pressure
switch, another to the manometer of known accuracy and appropriate range, and
apply pressure through the third tube. Make nal approach to the set point very
slowly. Note that manometer and pressure switch will have different response
times due to different internal volumes, lengths of tubing, uid drainage etc. Be
certain the switch is checked in the position it will assume in use, i.e. with
diaphragm in a vertical plane and switch lettering and nameplate in an upright
position.
C. For highly critical applications it is a good idea to check the set point adjustment
and reset it as necessary once or twice in the rst few months of operation. This
will compensate for any change in initial tension which may occur in the spring
and diaphragm. For most applications this change will not be signicant and no
resetting will be required.
CAUTION
5. Switch loads should not exceed the maximum specied current rating of 15 amps
resistive. Switch capabilities decrease with high load inductance or rapid cycle
rates. Whenever an application involves either of these factors, the user may nd
it desirable to limit the switched current to 10 amps or less in the interest of
prolonging switch life.
Do not exceed the specied voltage rating. Permanent damage
not covered by warranty may result.
MAINTENANCE
Moving parts of these switches are sealed in and are permanently tamper proof. The
single adjustment is that of the set point. Care should be taken to keep the switch
reasonably dry and free from dust or dirt. No lubrication or unusual precautions are
required for normal use.
DWYER INSTRUMENTS, INC.
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