Omega Engineering PSW141 User Manual

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User’s Guide

PSW-141 Series

Low Differential Pressure Switch

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

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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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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.

INSTALLATION OF PSW-141 PRESSURE

SWITCH

NOTE:

Each switch is calibrated in the vertical
position. It is recommended the switch be
mounted in the vertical position, as viewed
in Figure 1. Any adjustments to the
setpoint or deadband should be performed
with the instrument in the mounted position.

The PSW-141 differential pressure switch is suitable for clean air
or inert gas applications. If dust is present, a small in-line filter is
recommended to insure long, trouble-free operation. The normal
operating temperature range is from 0°C to 45°C (32°F to 115°F),
and the normal humidity range from 10% to 90% R.H.

Air connections are by means of 3/16 (4.75mm) barbed fittings
suitable for 1/4 O.D. polyethylene tubing (6mm), 1/8 I.D. Tygon or
polyurethane tubing (3 - 4mm).
The two mounting holes are 0.19 (4.8mm) in diameter and are
suitable for #8 or #10 mounting screws.
Electrical connections are by means of 3/8 terminal strips with #6
screws.
Spacing between mounting holes: 4.75 inches (121 mm).
Care should be taken not to exceed the maximum overpressure.

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Power consumption is .35 W for the DC powered units,

1.70 W for the 24 Vac and 1.90 W for the 120 Vac.

The power supply leads are connected to the two leftmost termi­nals (terminals 1 and 2) on the terminal strip. The relay terminals
are accessed across terminals 3, 4, and 5, refer to Figure 1.

The pressure switch comes with Setpoint and Deadband Adjust­ments. These are adjusted at the factory to activate on either fall­ing or rising pressure. The setpoint is factory set to activate at the
maximum pressure. The deadband is set to 5% of the maximum
pressure.

SETPOINT/DEADBAND ADJUSTMENT PROCEDURE

The set point and deadband are field adjustable so long as an
accurate pressure source is available and a qualified technician
performs the adjustments. The low pressure switches are extremely
sensitive to sudden pressure changes.

To gain access to the Setpoint or Deadband potentiometers re­move the black hole plugs above the Setpoint and Deadband la­bels, located on the top left of the instrument. To access either
potentiometer use a slotted 3/32 screw driver.

Connect the switch to its appropriate power supply.

Figure 1

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Table 2

Setpoint Adjustment

Apply full pressure, (or the pressure at which the setpoint is to
activate). Rotate the 20 turn Setpoint potentiometer, until the ohm­meter changes state. Turn clockwise to increase the set point and
counter-clockwise to decrease the set point

Slowly decrease the pressure until the relay deactivates. The dif­ference between the pressure at which the relay deactivates and
the pressure at which the relay activates is the deadband. If more
deadband is required, turn the deadband potentiometer and re­peat the previous steps. Adjustment of the deadband will have a
slight effect on the set point, therefore it will be necessary to re­peat these steps several times.

RELAY SPECIFICATIONS

The output of the SPDT (1 Form C) relay contact is rated at:

5A @ 30 VDC/120 VAC Resisitive

4A @ 240 VAC Resistive
Gold-plated relay contacts.
Electrical life expectancy: 100 x 10

3

ops. minimum @ 5A
Isolation between coil and contacts: 2000 VAC 1 minute
Maximum switched power: 600 VA (AC) or 120 W (DC)
Operate Time: 8 ms, max (Excluding Bounce)
Release Time: 4 ms, max (Excluding Bounce)

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Connect an ohmmeter to the relay contacts common and nor­mally closed or normally open. If a switch was ordered with a
relay activated on Rising Pressure and the ohmmeter terminals
are connected to the normally closed and common of the relay,
with no pressure applied, the ohmmeter should read 0 or closed,
refer to Table 2.

Deadband Adjustment

To set the deadband to zero, turn the Deadband potentiometer
fully counter-clockwise . Zero deadband will cause the relay to
chatter. It is recommended that some amount of deadband be
used. Turning the deadband potentiometer clockwise increases
the deadband.

PSW-141 Series M-3488 / 0011

WARRANTY/DISCLAIMER

OMEGA ENGINEERING, INC. warrants this unit to be free of defects in materials and workmanship for a
period of 13 months from date of purchase. OMEGA’s Warranty adds an additional one (1) month grace
period to the normal one (1) year product warranty to cover handling and shipping time. This
ensures that OMEGA’s customers receive maximum coverage on each product.

If the unit malfunctions, it must be returned to the factory for evaluation. OMEGA’s Customer Service
Department will issue an Authorized Return (AR) number immediately upon phone or written request.
Upon examination by OMEGA, if the unit is found to be defective, it will be repaired or replaced at no
charge. OMEGA’s WARRANTY does not apply to defects resulting from any action of the purchaser,
including but not limited to mishandling, improper interfacing, operation outside of design limits,
improper repair, or unauthorized modification. This WARRANTY is VOID if the unit shows evidence of
having been tampered with or shows evidence of having been damaged as a result of excessive corrosion;
or current, heat, moisture or vibration; improper specification; misapplication; misuse or other operating
conditions outside of OMEGA’s control. Components which wear are not warranted, including but not
limited to contact points, fuses, and triacs.

OMEGA is pleased to offer suggestions on the use of its various products. However,
OMEGA neither assumes responsibility for any omissions or errors nor assumes liability for any
damages that result from the use of its products in accordance with information provided by
OMEGA, either verbal or written. OMEGA warrants only that the parts manufactured by it will be
as specified and free of defects. OMEGA MAKES NO OTHER WARRANTIES OR
REPRESENTATIONS OF ANY KIND WHATSOEVER, EXPRESS OR IMPLIED, EXCEPT THAT OF TITLE,
AND ALL IMPLIED WARRANTIES INCLUDING ANY WARRANTY OF MERCHANTABILITY AND FIT­NESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED. LIMITATION OF
LIABILITY: The remedies of purchaser set forth herein are exclusive, and the total liability of
OMEGA with respect to this order, whether based on contract, warranty, negligence,
indemnification, strict liability or otherwise, shall not exceed the purchase price of the
component upon which liability is based. In no event shall OMEGA be liable for
consequential, incidental or special damages.

CONDITIONS: Equipment sold by OMEGA is not intended to be used, nor shall it be used: (1) as a “Basic
Component” under 10 CFR 21 (NRC), used in or with any nuclear installation or activity; or (2) in medical
applications or used on humans. Should any Product(s) be used in or with any nuclear installation or
activity, medical application, used on humans, or misused in any way, OMEGA assumes no responsibility
as set forth in our basic WARRANTY/DISCLAIMER language, and, additionally, purchaser will indemnify
OMEGA and hold OMEGA harmless from any liability or damage whatsoever arising out of the use of the
Product(s) in such a manner.

RETURN REQUESTS / INQUIRIES

Direct all warranty and repair requests/inquiries to the OMEGA Customer Service Department. BEFORE
RETURNING ANY PRODUCT(S) TO OMEGA, PURCHASER MUST OBTAIN AN AUTHORIZED RETURN
(AR) NUMBER FROM OMEGA’S CUSTOMER SERVICE DEPARTMENT (IN ORDER TO AVOID
PROCESSING DELAYS). The assigned AR number should then be marked on the outside of the return
package and on any correspondence.

The purchaser is responsible for shipping charges, freight, insurance and proper packaging to prevent
breakage in transit.

FOR W

ARRANTY RETURNS, please have the
following information available BEFORE
contacting OMEGA:

1. Purchase Order number under which the product

was PURCHASED,

2. Model and serial number of the product under

warranty, and

3. Repair instructions and/or specific problems

relative to the product.

FOR NON-WARRANTY REPAIRS,

consult OMEGA
for current repair charges. Have the following
information available BEFORE contacting OMEGA:

1. Purchase Order number to cover the COST

of the repair,

2. Model and serial number of the product, and

3. Repair instructions and/or specific problems

relative to the product.

OMEGA’s policy is to make running changes, not model changes, whenever an improvement is possible. This affords
our customers the latest in technology and engineering.

OMEGA is a registered trademark of OMEGA ENGINEERING, INC.
© Copyright 1999 OMEGA ENGINEERING, INC. All rights reserved. This document may not be copied, photocopied,

reproduced, translated, or reduced to any electronic medium or machine-readable form, in whole or in part, without the
prior written consent of OMEGA ENGINEERING, INC.

MADE IN

PSW-141 Series M-3488 / 0011

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