pg 1 12/10/03 6:01 PM Page 1 introduction Index Helpful Information Glossary of Terms Products from Dwyer New Products Dwyer Instruments, Inc. Engineering and Applications Handbook 1–4 4 5–7 8 Pressure Measurement Control To help engineers solve design, manufacturing and physical plant problems, Dwyer Instruments, Inc. has developed this Engineering and Product Applications handbook. When such problems involve the measurement or control of gage or differential pressure, temperature, level or flow, chances are there is a Dwyer Instruments product that can provide the solution. Reviewing the applications illustrated in this handbook may trigger an idea for a new approach to solving your engineering problems. For design engineers, these applications may also suggest ways to solve a customer problem and become the basis for a new product development. The information contained in this handbook may also suggest a more reliable, convenient and lower cost approach when reworking an existing product or system design. In many cases the application suggestions may cut costs by increasing efficiency through continuous control of systems and processes. The Engineering and Applications handbook also illustrates how engineers and technicians find applications for Dwyer controls and gages on a wide range of products serving a broad spectrum of industries and markets. The Dwyer Instruments, Inc. full-line catalog and its websites deliver the convenience and assistance you want from an instrumentation company. Our catalogs are available to you free of charge via telephone, fax or websites. In addition, our websites contain installation and operating manuals on our products that are easily downloadable to your computer or printer. Total customer service is our goal. 9 – 12 12 – 24 Flow/Air Velocity Air/Gas Liquid 24 – 33 34 – 40 Level Liquid Process Control 40 – 43, 45 41 43 – 45 Temperature Control 45 – 49 Valves Control Process 48 – 49 50 Miscellaneous Process 50 Analyze/Measure/Control 51 Reference Important Note: 52 Instruments, Inc., nor the Mercoid, Proximity, Love Controls or W.E. Anderson Divisions, shall be liable for loss, damage, or expense directly or indirectly arising from the use of any product described herein. In no event shall any of these Companies be liable for direct, indirect, special, or consequential damages. © Copyright 2003 Dwyer Instruments, Inc. No part of this handbook may be reproduced in any form without the express written consent of Dwyer Instruments, Inc. The gage and control hook-ups and sketches, and other application information shown in this Handbook are generalized and abbreviated to present the basic application idea only and no proprietary information has been revealed. We believe this application information to be reliable, but is intended for use by persons, at their own discretion, having technical skill and knowledge of the business. Neither Dwyer 1

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pg 2 12/10/03 6:03 PM Page 1 helpful information However, AC arcing associated with resistive loads is self-extinguishing, as the voltage goes to zero at a rate equal to the line frequency. Inductive AC loads also require significant derating of the switch. This is due to the high voltage surge created when the circuit is broken, resulting in heavy momentary arcing which can destroy the switch contacts. The best solution to control DC or inductive AC loads with Dwyer differential pressure switches is the use of an appropriate interface device, such as a mechanical relay or solid-state switching...

pg 3 12/10/03 6:05 PM Page 1 helpful information Magnehelic® gage as an air-flow monitor in a ventilation system, favor measuring total differential pressure across the blower versus sensing only static, velocity, or even total pressure on just one side or the other. When it is necessary to repeatedly pressurize and depressurize a system, you can minimize or eliminate unwanted switch closures or annoying full-scale gage pointer deflection by placing suitable restrictors in the line on both sides or in some cases, only the low-volume side of the switch or gage. When using Dwyer Magnehelic® differential...

pg 4 12/10/03 6:09 PM Page 1 helpful information Additional Design Precautions for Mercoid Products, continued For steam service of 35 psig or higher, or high temperature media, a siphon or remote connection is recommended to ensure that the ambient temperature rating of the switch is not exceeded. When applying a Mercoid Bourdon tube pressure switch with flammable, hazardous or toxic gases or liquids, a stainless steel Bourdon tube control should be specified as the welded Bourdon tube will reduce chances of leakage in case of fire. For applications with any chloride media, the use of a 316SS...

pg 5 12/10/03 6:19 PM Page 1 products from Dwyer Series 1223 Flex-Tube® U-tube ® Magnehelic differential pressure gage Model 424 Durablock® Inclined-Vertical ® Capsuhelic differential pressure gage Mark II Series 475 Mark III handheld digital manometer Series 490 wet/wet handheld digital manometer Photohelic® pressure switch/gage Manometers Dwyer manufactures a wide variety of virtually unbreakable plastic manometers. Both portable and stationary manometers of the U-tube, well-type, inclined and inclined-vertical types provide for the measurement of low range air pressures, pressure differentials...

pg 6 12/16/03 5:46 PM Page 1 products from Dwyer Model 1638 Model H3 Model H-2 Duotect® pressure switch Model 1950 explosion-proof Series A1PS/A1VS Mercoid® pressure 1000 Series switch pressure switch Pressure Switches Series MDA Pressure Series MDS Switch Pressure Switch Model 1910 Model 1823 pressure/flow/level products Dwyer offers a wide range of differential pressure switches, including explosion-proof models, which are precision diaphragm operated and which can be actuated by positive, negative or differential pressures. Designed for low and very low pressure differential, ranges from .03˝...