Omega Engineering PSW490B, PSW790B, DSW490B, DSW790B User Manual

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TM

®

User’s Guide

DSW490B and DSW790B

Pressure Control Switches

Servicing North America:

USA: One Omega Drive, P.O. Box 4047

ISO 9001 Certified Stamford CT 06907-0047

TEL: [phone] FAX: [phone]
e-mail: [e-mail]

Canada: 976 Bergar

Laval (Quebec) H7L 5A1
TEL: [phone] FAX: [phone]
e-mail: [e-mail]

For immediate technical or application assistance:

USA and Canada: Sales Service: 1-800-826-6342 / 1-800-TC-OMEGA

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Customer Service: 1-800-622-2378 / 1-800-622-BEST

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Engineering Service: 1-800-872-9436 / 1-800-USA-WHEN

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TELEX: 996404 EASYLINK: 62968934 CABLE: OMEGA

Mexico: Tel: [phone] FAX: [phone]

En Espan˜ ol: [phone]-7803 e-mail: [e-mail]

[e-mail]

Servicing Europe:

Benelux: Postbus 8034, 1180 LA Amstelveen, The Netherlands

TEL: [phone] FAX: [phone]
Toll Free in Benelux: 0800 0993344
e-mail: [e-mail]

Czech Republic: Rudé armády 1868, 733 01 Karviná

TEL: [phone] FAX: [phone]
Toll Free in Czech Rep.: 0800-1-66342 e-mail: [e-mail]

France: 9, rue Denis Papin, 78190 Trappes

TEL: [phone] FAX: [phone]
Toll Free in France: 0800-4-06342
e-mail: [e-mail]

Germany/Austria: Daimlerstrasse 26, D-75392 Deckenpfronn, Germany

TEL: [phone] FAX: [phone]
Toll Free in Germany: 0800 TC-OMEGA

SM

e-mail: [e-mail]

United Kingdom: One Omega Drive, River Bend Technology Centre

ISO 9002 Certified Northbank, Irlam, Manchester

M44 5EX, United Kingdom
TEL: [phone] FAX: [phone]
Toll Free in the United Kingdom: 0800 488 488
e-mail: [e-mail]

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OMEGAnet®On-Line Service Internet e-mail

www.omega.com [e-mail]

It is the policy of OMEGA to comply with all worldwide safety and EMC/EMI regulations that
apply. OMEGA is constantly pursuing certification of its products to the European New Approach
Directives. OMEGA will add the CE mark to every appropriate device upon certification.

The information contained in this document is believed to be correct, but OMEGA Engineering, Inc. accepts
no liability for any errors it contains, and reserves the right to alter specifications without notice.
WARNING: These products are not designed for use in, and should not be used for, patient-connected applications.

TM

®

INTRODUCTION

The OMEGA differential pressure switch is a
precision built U.L. approved control device
which features a mechanical snap action switch.
Controllers are available for operation on vari­ous pressure differentials with fixed or variable
switching differentials. The standard electrical
switch is SPDT and is available with various
electrical characteristics.

Two SPDT switch elements mounted together
are available. Various wetted material construc­tions for compatibility with a wide range of
pressure media may be obtained.

The snap action differential pressure switch is
furnished in the standard NEMA 4/4X and explo­sion proof NEMA 7 and 9 enclosure styles. Both
enclosures are epoxy coated aluminum castings.

INSTALLATION

These controls are precision instruments and
should never be left with internal components
exposed. During installation insure that covers
are in place and conduit openings are closed
except when actually working on the control.

MOUNTING DSW490 AND DSW790 SERIES

There are three holes external to the enclosure
for surface mounting. Location of these holes is
shown on the general dimension drawing. They
may also be mounted directly on pressure line
using the pressure connections.

ELECTRICAL CONNECTIONS

Remove cover
DSW490 Series – two screws hold cover to
enclosure
DSW790 Series – cover unscrews

CONDUIT CONNECTIONS

Note – It is recommended that Teflon®tape or
other sealant be used on conduit, bushing or
plug threads to ensure integrity of the enclosure.

INSTALLATION AND MAINTENANCE OF THE

DSW490B AND DSW490B SERIES

OMEGA®SNAP ACTION SWITCHES

FOR DIFFERENTIAL PRESSURE CONTROL

DSW490 series standard – one 3⁄

4 NPT conduit

hole right side.

DSW790 series standard – two

3

⁄

4 NPT conduit

holes with one permanent plug. NEMA 7 & 9
enclosures require proper conduit seals and
breathers as per the National Electrical Code.

DSW490 SERIES
SPDT

– Wire directly to the switch according to

circuit requirements.

2-SPDT – Dual switching elements consist of
two SPDT switches mounted together in a
bracket. Switches are calibrated to have simul­taneous operation within 1% of range either on
increasing or decreasing pressure but not in
both directions. Wire directly to the front and
rear switch according to circuit requirements.
Leads are provided on rear switch color coded
as follows:
Common – White
Normally Closed – Red
Normally Open – Blue

When hermetically sealed switch element(s) are
supplied, the lead color coding is as follows:
Common – White
Normally Closed – Red
Normally Open – Blue

DSW790 SERIES
SPDT

– Wire directly to the switch according to

circuit requirements.

2-SPDT – Wire to front switch terminal block
(left) and rear switch terminal block (right) as
marked. Strip insulation

5

⁄

16,˝ insert in proper

terminal connector and tighten clamping screw
to secure.

ADJUSTMENT OF SETPOINT

DSW490 & DSW790 Series – A single setpoint
adjustment nut (

7

⁄

8˝) is located centrally at the

bottom on the inside of the enclosure.