Dwyer 1630 User Manual

Series 1630 – Differential Pressure Switch

DIAPHRAGM

1/2

[12.70]

TYP.

ADJUSTMENT

SCREW

2

[50.80]

TYP

3

[76.20]

6-1/2

[165.10]

1/8 NPT(F) LOW

PRESSURE CONNECTION

1/8 NPT(F) HIGH

PRESSURE CONNECTION

1/2

CONDUIT

CONNECTION

SPDT SNAP

SWITCH

SCREW TYPE
ELECTRICAL
TERMINALS
TYP 3 PLACES

8-3/16

[207.96]

Ø7-3/4

[196.85]

CONDUIT

ENCLOSURE

ADJUSTABLE

RANGE SPRING

Ø9/32 [7.14]

MOUNTING HOLE

TYP 4 PLACES

3

[76.20]

TYP

4

[101.60]

8-7/8

[225.43] SQ

9-3/4

[247.65] TYP

10-7/8

[276.23] TYP

1-1/4

[31.75]

7-1/8

[180.98]

3-7/8

[98.43]

1/2 NPT
ELECTRICAL
CONNECTION

1/8 NPT HIGH
PRESSURE
CONNECTION

1/8 NPT LOW
PRESSURE CONNECTION

1-5/16
[33.34]

7

[177.80]

TYP

Specifications – Installation and Operating Instructions

Model 1638 pressure switch ­U.L. and C.S.A. listed F.M. approved

Our highest precision conventional large diaphragm

pressure switch provides maximum dependability. In addi­tion it incorporates a visible set point indicator for maximum
convenience. U.L. and C.S.A. listed, F.M. approved for gen­eral service, these switches are suitable for most applica­tions in air conditioning and industrial service. Electrical
capability of 15 amps handles most small electrical loads.

Environmental (MIL) Construction. Unlisted Model 1635
can be furnished with special snap switch and silicone rub­ber diaphragm for high humidity and/or for government
applications. Similar to standard Model 1638 except dead
band is slightly greater. Specify Model No. 1635 (range No.)
MIL in ordering. Example: 1635-5-MIL.

HOUSINGS FOR USE WITH MODEL 1638 SWITCH

(also suitable for Models 1626, 1627 and 1640 switches)

Weatherproof Housing

16 ga. steel enclosure for
unusually wet or oily con­ditions. Withstands 200
hour salt spray test.
Gasketed cover. Weight,
20 lbs. Switch must be
installed at factory.
Specify “WP” in addition
to switch catalog.

Explosion-proof Housing

Killark cast alum. housing No. 4GRH with dome for No. 1638 switches and No.
GRH with flat cover for No. 1626 and 1627 switches rated for Class I, Group D;
Class II, Groups E, F and G and Class III. Approximate weight, 47 lbs. Specify
“EXPL” in addition to switch catalog number.

13-5/8

[346.08]

12

TYP

[304.80]

TYP

11

[279.4]

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361 U.S.A.

10-3/4

[273.05]

TYP

12

[304.80]

Ø3/8 [9.53]
MOUNTING HOLES TYPE 4 PLACES

1/8 NPT HIGH
PRESSURE
CONNECTION

BREATHER

1/8 NPT LOW
PRESSURE
CONNECTION

3/4

[19.05]

TYP

[88.90]

[298.45]

3-1/2

11-3/4

3/4 NPT

ELECTRICAL

CONNECTION

2-1/8

[53.98]

3/4

[19.05]

TYP

6

[152.40]

Bulletin E-52

PHYSICAL DATA

Temperature Limits: -30°F (-34.4°C) for dry air or gas to 110°F

(43.3°C). (Consult factory for higher temperature applications.)

Maximum Surge Pressure: 25 psig.
Rated Pressure: 10 psig.
Pressure Connections:
Electrical Rating: 15 amps, 120-480 volts, 60 Hz. A.C.

Resistive

1

/8H.P. @ 125 volts, 1/4 H.P. @ 250 volts, 60 Hz. A.C.

1

/8″ NPT(F).

Wiring Connections: 3 screw type, common, normally open
and normally closed.

Set Point Adjustment: Screw type with enclosed scale.
Housing: 16 ga. steel, zinc plated, dichromate dipped for 200

hour salt spray test.

Diaphragm: Silicone rubber.
Calibration Spring: Stainless steel.
Weight: 4 lbs., 14 oz. (2.21 kg).
Installation: Diaphragm vertical.

MODEL 1638:
Operating Ranges, Dead Bands and Ratings.
U.L. and C.S.A. Listed, F.M. Approved.

Approximate

Dead Band

At Min.

Set Point

0.04

0.04

0.06

0.07

0.11

At Max.

Set Point

0.05

0.06

0.08

0.25

0.30

Model

Number

1638-0
1638-1
1638-2
1638-5
1638-10

Operating

Range

Inches,

W.C.

0.05 to 0.25

0.20 to 1.0

1.0 to 3.0

2.0 to 6.0

3.0 to 12

Suggested Specification

Differential pressure switches shall be diaphragm operated
to actuate a single pole double throw snap switch. Motion
of the diaphragm shall be restrained by a calibrated spring
that can be adjusted to set the exact pressure differ ential at
which the electrical switch will be actuated. Motion of the
diaphragm shall be transmitted to the switch button by
means of a direct mechanical linkage. Set point adjustment
shall be screw type with set point indicated on a visual
scale. Switches shall be Dwyer Instruments, Inc. Catalog
No. 1638-_____ for the required operating ranges.

Phone: [phone] www.dwyer-inst.com
Fax: [phone] e-mail: [e-mail]
Lit-by-Fax: [phone]

INSTALLATION

1. Select a location free from excessive vibration where oil
or water will not drip on the switch and where ambient tem­perature will be within a range of -30°F (-34.4°C) (dry air or
gas) to 110°F (43.3°C). See special housing for unusual
requirements and MIL option for high humidity.

Bulletin E-52

Page 2

ment screw, counter-clockwise to increase the pressure
setting or clockwise to decrease the setting. Note that the
indicated calibration is correct only if the switch is mounted
with the diaphragm assembly in a vertical plane. If mounted
in any other position, the switch must be recalibrated as fol­lows:

2. MOUNT THE SWITCH WITH THE DIAPHRAGM IN A
VERTICAL PLANE. The switch is position sensitive so it
must be recalibrated for each change in operating position.

3. Connect switch to source of air pressure differential.
Metal tubing with 1/4″ O.D. is recommended, but any tub­ing system which will not restrict the air flow is satisfactory.

4. Electrical connections for all switches are marked
Common, Normally Open and Normally Closed. Be certain
connections are properly made and that no mechanical load
can be transferred from the wiring to the snap switch.

ADJUSTMENT AND CALIBRATION

1. The calibration or actuation point of the switch is indicat­ed on the scale secured to the transparent range spring
enclosure. Recalibration to another setting within the range
of the switch is readily accomplished by turning the adjust-

a. Using a “T” assembly with three rubber tubing leads, all
as short as possible and offering minimum flow resistance,
run one lead to the pressure switch and the second lead to
a manometer of appropriate range and known accuracy.
Apply pressure through the third tube, preferably by suc­cessively pinching the tube tight with the fingers. Pinch off
the tube and make the final approach to the set point slow­ly. Check the set point by listening for the click of the switch
or by using a volt meter.

b. Note that the manometer and pressure switch will have
different response characteristics due to their different inter­nal volumes, lengths of tubing, fluid drainage, etc. Be cer­tain that the switch is checked in the position it will assume
in use, or preferably, that it is installed in its final location and
then checked. When pressure reading has been estab­lished, replace scale to proper position, relating set point
indicator to markings on scale.

Ø9/32 [7.14]

MOUNTING HOLE

TYP 4 PLACES

ADJUSTMENT

SCREW

4

[101.60]

[12.70]

ADJUSTABLE

RANGE SPRING

3

[76.20]

TYP

1/2

TYP.

1/8 NPT(F) LOW

PRESSURE CONNECTION

2

[50.80]

TYP

3

[76.20]

DIAPHRAGM

CONDUIT

ENCLOSURE

Ø7-3/4

[196.85]

8-3/16

[207.96]

SCREW TYPE
ELECTRICAL
TERMINALS
TYP 3 PLACES

SPDT SNAP

SWITCH

1/2

CONDUIT

CONNECTION

6-1/2

[165.10]

1/8 NPT(F) HIGH

PRESSURE CONNECTION

©Copyright 2001 Dwyer Instruments, Inc. Printed in U.S.A. 1/01 FR# 23-440200-00 Rev.1

DWYER INSTRUMENTS, INC.

P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361 U.S.A.

Phone: [phone] www.dwyer-inst.com
Fax: [phone] e-mail: [e-mail]
Lit-by-Fax: [phone]