Pentair Pressure Relief Valve Engineering Handbook

1 Pentair Pressure Relief Valve Engineering HandbookAnderson Greenwood, Crosby and Varec ProductsVALVES & CONTROLSP entair Pressure Relief Valve Engineering Handbook ForwardTechnical Publication No. TP-V300 PVCMC-0296-US-1203 rev 12-2012 Copyright 2012 Pentair Valves & Controls. All rights reserved. No part of thispublication may be reproduced or distributed in any form or by any means, or stored in adatabase or retrieval system, without written permission. Pentair Valves & Controls (PVC)provides the information herein in good faith but makes no representation as to itscomprehensiveness or accuracy. Individuals using this information in this publicationmust exercise their independent judgment in evaluating product selection anddetermining product appropriateness for their particular purpose and systemrequirements. PVC makes no representations or warranties, either express or implied,including without limitation any warranties of merchantability or fitness for a particularpurpose with respect to the information set forth herein or the product(s) to which theinformation refers.

2 Accordingly, PVC will not be responsible for damages (of any kind ornature, including incidental, direct, indirect, or consequential damages) resulting from theuse of or reliance upon this information. Pentair reserves the right to change productdesigns and specifications without notice. All registered trademarks are the property oftheir respective owners. Printed in the Pressure Relief Valve Engineering Handbook ContentsTechnical Publication No. TP-V300 PVCMC-0296-US-1203 rev 12-2012-US-1203 rev 12-2012 Copyright 2012 Pentair . All rights reserved. 1 2 Types of Parts of Pressure Relief Dimensional Characteristics Pressure Relief Operational Characteristics Pressure Relief System Characteristics 3 Codes and Standards American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel International Organization for Standardization (ISO) European Union American Petroleum Institute (API) National Fire Protection Agency (NFPA) National Board of Boiler and Pressure Vessel 4 Design Fundamentals Direct Spring Operated Pressure Relief Pilot Operated Pressure Relief Advantages and Limitations of Valve 5 Valve Sizing and Selection (USCS Units) Gas/Vapor Sizing Sonic Gas/Vapor Sizing Subsonic Steam Liquid Fire Two-Phase Flow Noise Level Reaction 6 - Valve Sizing and Selection (Metric Units)

3 Gas/Vapor Sizing Sonic Gas/Vapor Sizing Subsonic Steam Liquid Fire Two-Phase Flow Noise Level Reaction of Contents Pentair Pressure Relief Valve Engineering Handbook ContentsTechnical Publication No. TP-V300 PVCMC-0296-US-1203 rev 12-2012 Copyright 2012 Pentair . All rights reserved. 7 Engineering Support Information (USCS Units) Compressibility Capacity Correction Factor for Back Capacity Correction Factor for High Pressure Capacity Correction Factor for Capacity Correction Factor for Ratio of Specific Heats and Coefficient Typical Fluid Saturated Steam Pressure Orifice Area and Coefficient of Discharge for Anderson Greenwood and Crosby Pressure Relief Valves Equivalents and Conversion Capacity Correction Factor for Rupture Disc/ Pressure Relief Valve 8 Engineering Support Information (Metric Units) Compressibility Capacity Correction Factor for Back Capacity Correction Factor for High Pressure Capacity Correction Factor for Capacity Correction Factor for Ratio of Specific Heats and Coefficient Typical Fluid Saturated Steam Pressure Orifice Area and Coefficient of Discharge for Anderson Greenwood and Crosby Pressure Relief Valves Equivalents and Conversion Capacity Correction Factor for Rupture Disc/ Pressure Relief Valve of Contents (continued) Pentair Pressure Relief Valve Engineering Handbook Chapter 1 - IntroductionTechnical Publication No.

4 TP-V300 PVCMC-0296-US-1203 rev 12-2012 Copyright 2012 Pentair . All rights reserved. primary purpose of a Pressure or vacuum Relief valveis to protect life and property by venting process fluidfrom an overpressurized vessel or adding fluid (such asair) to prevent formation of a vacuum strong enough tocause a storage tank to collapse. Proper sizing, selection, manufacture, assembly, testing,installation, and maintenance of a Pressure Relief Valve areall critical for optimal protection of the vessel or note that the brand names of Pressure reliefdevices covered (Anderson Greenwood, Crosby,Whessoe and Varec) are of Pentair manufacture. Aspecific Valve brand is selected, according to pressurerange, temperature range, Valve size, industry applicationand other applicable manual has been designed to provide a service toPentair customers by presenting reference data andtechnical recommendations based on over 125 years ofpioneering research, development, design, manufactureand application of Pressure Relief valves.

5 Sufficient data issupplied so that an individual will be able to use thismanual as an effective aid to properly size and selectPentair-manufactured Pressure Relief devices for specificapplications. Information covering terminology, standards,codes, basic design, sizing and selection are presentedin an easy to use information contained in this manual is offered as aguide. The actual selection of valves and Valve productsis dependent on numerous factors and should be madeonly after consultation with qualified Pentair who utilize this information are reminded of thelimitations of such publications and that there is nosubstitute for qualified Engineering Pressure Relief devices are manufactured inaccordance with a controlled quality assurance programwhich meets or exceeds ASME Code quality controlrequirements. Capacities of valves with set pressures of15 psig, or higher, are certified by the National Board ofBoiler and Pressure Vessel Inspectors.

6 These attributesare assured by the presence of an ASME Code SymbolStamp and the letters NB on each Pressure Relief valvenameplate. Lower set pressures are not addressed byeither the National Board or ASME; however, capacities atlower set pressures have been verified by actual testing atPentair s extensive flow lab facilities. Pentair s range ofpressure Relief valves are designed, manufactured, andtested in strict accordance with a quality managementsystem approved to the International StandardOrganization s ISO 9000 quality standard proper sizing and selection, the user can thus beassured that Pentair s products are of the highest qualityand technical standards in the world of Pressure in doubt as to the proper application of anyparticular data, the user is advised to contact thenearest Pentair sales office or sales has a large staff of highly trained personnelstrategically located throughout the world, who areavailable for your has designed and has available to customers acomputer sizing program for Pressure Relief valves,PRV2 SIZE( Pressure Relief Valve and Vent SizingSoftware).

7 The use of this comprehensive program allowsan accurate and documented determination of suchparameters as Pressure Relief Valve orifice area andmaximum available sizing program is a powerful tool, yet easy to use. Itsmany features include quick and accurate calculations,user-selected units of measurement, selection of pressurerelief Valve size and style, Valve data storage, printedreports, Valve specification sheets and outline control via pop-up windows, function keys,extensive on-line help facilities, easy-to-read formattedscreens, flagging of errors, and easy editing of displayedinputs make the program easy to understand and operate. It is assumed that the program user has a generalunderstanding of Pressure Relief Valve sizing program user must remember they are responsiblefor the correct determination of service conditions and thevarious data necessary for input to the sizing program. For download instructions for the latest PRV2 SIZE pleasecontact your sales representative or information in this manual is not to be used forASME Section III nuclear applications.

8 If you needassistance with Pressure Relief valves for ASMES ection III service, please contact our nuclearindustry experts at Pressure Relief Valve Engineering Handbook Chapter 2 TerminologyTechnical Publication No. TP-V300 PVCMC-0296-US-1203 rev 12-2012 Copyright 2012 Pentair . All rights reserved. GeneralBench TestingTesting of a Pressure Relief device on a test stand usingan external Pressure source with or without an auxiliarylift device to determine some or all of its Capacity TestingTesting of a Pressure Relief device to determine itsoperating characteristics including measured TestingTesting of a Pressure Relief device installed on but notprotecting a system, using an external Pressure source,with or without an auxiliary lift device to determine someor all of its operating TestingTesting of a Pressure Relief device installed on andprotecting a system using system Pressure or an externalpressure source, with or without an auxiliary lift device todetermine some or all of its operating Relief DeviceA device designed to prevent Pressure or vacuum fromexceeding a predetermined value in a Pressure vessel bythe transfer of fluid during emergency or abnormalconditions.

9 II. Types of DevicesPressure Relief Valve (PRV)A Pressure Relief device designed to actuate on inlet staticpressure and to reclose after normal conditions havebeen restored. It may be one of the following types andhave one or more of the following design Restricted lift PRV: a Pressure Relief Valve in whichthe actual discharge area is determined by theposition of the Full lift PRV: a Pressure Relief Valve in which theactual discharge area is not determined by theposition of the Reduced bore PRV: a Pressure Relief Valve in whichthe flow path area below the seat is less than theflow area at the inlet to the Full bore PRV: a Pressure Relief Valve in which thebore area is equal to the flow area at the inlet to thevalve and there are no protrusions in the Direct spring loaded PRV: a Pressure Relief Valve inwhich the disc is held closed by a Pilot operated PRV: a Pressure Relief Valve in which apiston or diaphragm is held closed by systempressure and the holding Pressure is controlled by apilot Valve actuated by system Pressure .

10 G. Conventional direct spring loaded PRV: a directspring loaded Pressure Relief Valve whose operationalcharacteristics are directly affected by changes inthe back Balanced direct spring loaded PRV: a direct springloaded Pressure Relief Valve which incorporatesmeans of minimizing the effect of back Pressure onthe operational characteristics (opening Pressure ,closing Pressure , and relieving capacity).I. Internal spring PRV: a direct spring loaded pressurerelief Valve whose spring and all or part of theoperating mechanism is exposed to the systempressure when the Valve is in the closed position. J. Temperature and Pressure Relief Valve : a pressurerelief Valve that may be actuated by Pressure at thevalve inlet or by temperature at the Valve Power actuated PRV: a Pressure Relief Valve actuatedby an externally powered control ValveA Pressure Relief Valve characterized by rapid opening orclosing and normally used to relieve compressible Valve A Pressure Relief Valve characterized by gradual opening orclosing generally proportional to the increase or decreasein Pressure .