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class="vector-toc-numb">2</span> <span>Measuring safety performance</span> </div> </a> <ul id="toc-Measuring_safety_performance-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Benefits" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Benefits"> <div class="vector-toc-text"> <span class="vector-toc-numb">3</span> <span>Benefits</span> </div> </a> <button aria-controls="toc-Benefits-sublist" class="cdx-button cdx-button--weight-quiet cdx-button--icon-only vector-toc-toggle"> <span class="vector-icon mw-ui-icon-wikimedia-expand"></span> <span>Toggle Benefits subsection</span> </button> <ul id="toc-Benefits-sublist" class="vector-toc-list"> <li id="toc-Safety_benefits" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Safety_benefits"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.1</span> <span>Safety benefits</span> </div> </a> <ul id="toc-Safety_benefits-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Production_benefits" class="vector-toc-list-item vector-toc-level-2"> <a class="vector-toc-link" href="#Production_benefits"> <div class="vector-toc-text"> <span class="vector-toc-numb">3.2</span> <span>Production benefits</span> </div> </a> <ul id="toc-Production_benefits-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-Drawbacks" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Drawbacks"> <div class="vector-toc-text"> <span class="vector-toc-numb">4</span> <span>Drawbacks</span> </div> </a> <ul id="toc-Drawbacks-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-Techniques" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#Techniques"> <div class="vector-toc-text"> <span class="vector-toc-numb">5</span> <span>Techniques</span> </div> </a> <button 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</a> <ul id="toc-Integrated_solenoid_valve_systems-sublist" class="vector-toc-list"> </ul> </li> </ul> </li> <li id="toc-References" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#References"> <div class="vector-toc-text"> <span class="vector-toc-numb">6</span> <span>References</span> </div> </a> <ul id="toc-References-sublist" class="vector-toc-list"> </ul> </li> <li id="toc-External_links" class="vector-toc-list-item vector-toc-level-1 vector-toc-list-item-expanded"> <a class="vector-toc-link" href="#External_links"> <div class="vector-toc-text"> <span class="vector-toc-numb">7</span> <span>External links</span> </div> </a> <ul id="toc-External_links-sublist" class="vector-toc-list"> </ul> </li> </ul> </div> </div> </nav> </div> </div> <div class="mw-content-container"> <main id="content" class="mw-body"> <header class="mw-body-header vector-page-titlebar"> <nav aria-label="Contents" class="vector-toc-landmark"> <div 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data-event-name="pinnable-header.vector-appearance.pin">move to sidebar</button> <button class="vector-pinnable-header-toggle-button vector-pinnable-header-unpin-button" data-event-name="pinnable-header.vector-appearance.unpin">hide</button> </div> </div> </div> </nav> </div> </div> <div id="bodyContent" class="vector-body" aria-labelledby="firstHeading" data-mw-ve-target-container> <div class="vector-body-before-content"> <div class="mw-indicators"> </div> <div id="siteSub" class="noprint">From Wikipedia, the free encyclopedia</div> </div> <div id="contentSub"><div id="mw-content-subtitle"></div></div> <div id="mw-content-text" class="mw-body-content"><div class="mw-content-ltr mw-parser-output" lang="en" dir="ltr"><p><b><span lang="ko-kp">Partial</span> stroke testing</b> (or PST) is a technique used in a control system to allow the user to test a percentage of the possible failure modes of a <a href="/wiki/Shut_down_valve" class="mw-redirect" title="Shut down valve">shut down valve</a> without the need to physically close the valve. PST is used to assist in determining that the safety function will operate on demand. PST is most often used on high integrity <a href="/wiki/Shutdown_valve" title="Shutdown valve">emergency shutdown valves</a> (ESDVs) in applications where closing the valve will have a high cost burden yet proving the integrity of the valve is essential to maintaining a safe facility. In addition to ESDVs PST is also used on high integrity pressure protection systems or HIPPS. Partial stroke testing is not a replacement for the need to fully stroke valves as proof testing is still a mandatory requirement. </p> <meta property="mw:PageProp/toc" /> <div class="mw-heading mw-heading2"><h2 id="Standards">Standards</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Partial_stroke_testing&action=edit&section=1" title="Edit section: Standards"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Partial stroke testing is an accepted <a href="/wiki/Petroleum_industry" title="Petroleum industry">petroleum industry</a> standard technique and is also quantified in detail by regulatory bodies such as the <a href="/wiki/International_Electrotechnical_Commission" title="International Electrotechnical Commission">International Electrotechnical Commission</a> (IEC) and the <a href="/w/index.php?title=Instrument_Society_of_Automation&action=edit&redlink=1" class="new" title="Instrument Society of Automation (page does not exist)">Instrument Society of Automation</a> (ISA). The following are the standards appropriate to these bodies. </p> <dl><dd><ul><li><b><a href="/wiki/IEC61508" class="mw-redirect" title="IEC61508">IEC61508</a></b> – Functional safety of electrical/electronic/programmable electronic safety-related systems</li> <li><b><a href="/wiki/IEC61511" class="mw-redirect" title="IEC61511">IEC61511</a></b> – Functional safety – Safety instrumented systems for the process industry sector</li> <li><b>ANSI/ISA-84.00.01</b> – Functional safety: Safety instrumented systems for the process industry sector (an <a href="/wiki/American_National_Standards_Institute" title="American National Standards Institute">ANSI</a> standard)</li></ul></dd></dl> <p>These standards define the requirements for safety related systems and describe how to quantify the performance of PST systems </p> <div class="mw-heading mw-heading2"><h2 id="Measuring_safety_performance">Measuring safety performance</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Partial_stroke_testing&action=edit&section=2" title="Edit section: Measuring safety performance"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>IEC61508 adapts a <a href="/wiki/Safety_life_cycle" title="Safety life cycle">safety life cycle</a> approach to the management of plant safety. During the design phase of this life cycle of a safety system the required safety performance level is determined using techniques such as <a href="/wiki/Markov_analysis" class="mw-redirect" title="Markov analysis">Markov analysis</a>, <a href="/wiki/Failure_mode_and_effects_analysis" title="Failure mode and effects analysis">FMEA</a>, <a href="/wiki/Fault_tree_analysis" title="Fault tree analysis">fault tree analysis</a> and <a href="/wiki/Hazard_and_operability_study" title="Hazard and operability study">Hazop</a>. These techniques allow the user to determine the potential frequency and consequence of hazardous activities and to quantify the level of risk. A common method for this quantification is the <a href="/wiki/Safety_integrity_level" title="Safety integrity level">safety integrity level</a>. This is quantified from one to four with level four being the most hazardous. </p><p>Once the SIL level is determined this specifies the required performance level of the safety systems during the operational phase of the plant. The metric for measuring the performance of a safety function is called the average probability of failure on demand (or PFD<sub>avg</sub>) and this correlates to the SIL level as follows </p> <table class="wikitable"> <tbody><tr> <th>SIL</th> <th>PFD<sub>avg</sub> </th></tr> <tr> <td>4</td> <td>≥10<sup>−5</sup> to <10<sup>−4</sup> </td></tr> <tr> <td>3</td> <td>≥10<sup>−4</sup> to <10<sup>−3</sup> </td></tr> <tr> <td>2</td> <td>≥10<sup>−3</sup> to <10<sup>−2</sup> </td></tr> <tr> <td>1</td> <td>≥10<sup>−2</sup> to <10<sup>−1</sup> </td></tr></tbody></table> <p>One method of calculating the PFD<sub>avg</sub> for a basic safety function with no <a href="/wiki/Redundancy_(engineering)" title="Redundancy (engineering)">redundancy</a> is using the formula </p> <dl><dd><b>PFD<sub>avg</sub> = [(1-PTC)×λ<sub>D</sub>×(TI<sub>FC</sub>/2)] + [PTC×λ<sub>D</sub>×(TI<sub>PST</sub>/2)]</b></dd></dl> <p>Where: </p> <dl><dd>PTC = Proof test coverage of the partial stroke test.</dd></dl> <dl><dd>λ<sub>D</sub> = The dangerous failure rate of the safety function.</dd></dl> <dl><dd>TI<sub>FC</sub> = The full closure interval, i.e. how often the valve must be full closed for testing.</dd></dl> <dl><dd>TI<sub>PST</sub> = The partial stroke test interval.</dd></dl> <p>The proof test coverage is a measure of how effective the partial stroke test is and the higher the PTC the greater the effect of the test. </p> <div class="mw-heading mw-heading2"><h2 id="Benefits">Benefits</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Partial_stroke_testing&action=edit&section=3" title="Edit section: Benefits"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The benefits of using PST are not limited to simply the safety performance but gains can also be made in the production performance of a plant and the capital cost of a plant.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup><sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> These are summarised as follows </p> <div class="mw-heading mw-heading3"><h3 id="Safety_benefits">Safety benefits</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Partial_stroke_testing&action=edit&section=4" title="Edit section: Safety benefits"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Gains can be made in the following areas by the use of PST. </p> <dl><dd><ul><li>Reducing the probability of failure on demand.</li></ul></dd></dl> <div class="mw-heading mw-heading3"><h3 id="Production_benefits">Production benefits</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Partial_stroke_testing&action=edit&section=5" title="Edit section: Production benefits"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>There are a number of areas where production efficiency can be improved by the successful implementation of a PST system: </p> <ul><li>Extension of the time between compulsory plant shutdowns.</li> <li>Predicting potential valve failures facilitating the pre-ordering of spare parts.</li> <li>Prioritisation of maintenance tasks.</li></ul> <div class="mw-heading mw-heading2"><h2 id="Drawbacks">Drawbacks</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Partial_stroke_testing&action=edit&section=6" title="Edit section: Drawbacks"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The main drawback of all PST systems is the increased probability of causing an accidental activation of the safety system thus causing a plant <a href="/wiki/Plant_process_and_emergency_shutdown_systems#Emergency_shutdown_(ESD)" class="mw-redirect" title="Plant process and emergency shutdown systems">shutdown</a>, this is the primary concern of PST systems by operators and for this reason many PST system remain dormant after installation. Different techniques mitigate for this issue in different manners but all systems have an inherent risk </p><p>In addition in some cases, a PST cannot be performed due to the limitations inherent in the process or the valve being used. Further, as the PST introduces a disturbance into the process or system, it may not be appropriate for some processes or systems that are sensitive to disturbances. </p><p>Finally, a PST cannot always differentiate between different faults or failures within the valve and actuator assembly thus limiting the diagnostic capability. </p> <div class="mw-heading mw-heading2"><h2 id="Techniques">Techniques</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Partial_stroke_testing&action=edit&section=7" title="Edit section: Techniques"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>There are a number of different techniques available for partial stroke testing and the selection of the most appropriate technique depends on the main benefits the operator is trying to gain. </p> <div class="mw-heading mw-heading3"><h3 id="Mechanical_Jammers">Mechanical Jammers</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Partial_stroke_testing&action=edit&section=8" title="Edit section: Mechanical Jammers"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Mechanical jammers are devices where a device is inserted into the valve and actuator assembly that physically prevents the valve from moving past a certain point. These are used in cases where accidentally shutting the valve would have severe consequences, or any application where the end user prefers a mechanical device. </p><p>Typical benefits of this type of device are as follows:<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> </p> <ul><li>The devices assure metal-to-metal prevention of stroke past the specified set point.</li> <li>Unlike some electronic systems, there is no need to commission and calibrate controls or continually train personnel, resulting in additional significant cost savings.</li> <li>The devices are vibration resistant, making them highly reliable.</li> <li>The risk associated with having an ESD event occur at time of manual mechanical PST may be considered statistically insignificant and allows a rational consideration of the advantages mechanical devices offer.</li> <li>Modular design allows for addition of limit switches, potentiometers, remote control operation, etc.</li> <li>The test is a comprehensive test of the logic solver and all final elements, only the sensing elements of the safety function are not tested.</li> <li>The valve is tested at the designed operating speed as it simulates an ESD event</li> <li>Jammers have a very low probability of causing a spurious trip.</li></ul> <p>However, opinions differ whether these devices are suitable for functional safety systems as the safety function is offline for the duration of the test. </p><p>Modern mechanical PST devices may be <a rel="nofollow" class="external text" href="http://www.netherlocks.com/partial-stroke-testing/netherlocks-develops-remote-operation-for-faith-pst-system/">automated</a>. </p><p>Examples of this kind of device include direct interface products that mount between the valve and the actuator and may use cams fitted to the valve stem. An example of such a mechanical PST system:<sup id="cite_ref-4" class="reference"><a href="#cite_note-4"><span class="cite-bracket">[</span>4<span class="cite-bracket">]</span></a></sup> </p><p>Other methods include adjustable actuator end stops. </p> <div class="mw-heading mw-heading3"><h3 id="Pneumatic_valve_positioners">Pneumatic valve positioners</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Partial_stroke_testing&action=edit&section=9" title="Edit section: Pneumatic valve positioners"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>The basic principle behind partial stroke testing is that the valve is moved to a predetermined position in order to determine the performance of the shut down valve. This led to the adaptation of pneumatic positioners used on <a href="/wiki/Flow_control_valve" title="Flow control valve">flow control valve</a> for use in partial stroke testing. These systems are often suitable for use on shutdown valves up to and including SIL3. The main benefits are : </p> <ul><li>Elimination of the cost of manual testing</li> <li>Tracking and records of the PST tests for an optimum Safety monitoring. When the positioner is connected to the Safety System, the date and result of the test are registered in the Sequence of Events, for Insurance purposes.</li> <li>Remote access to valve diagnostics from the control room, with action oriented reports for <a href="/wiki/Predictive_maintenance" title="Predictive maintenance">predictive maintenance</a>.</li></ul> <p>The main benefit of these systems is that positioners are common equipment on plants and thus operators are familiar with the operation of these systems, however the primary drawback is the increased risk of spurious trip caused by the introduction of additional control components that are not normally used on on/off valves. These systems are however limited to use on pneumatically actuated valves. </p> <div class="mw-heading mw-heading3"><h3 id="Electrical_relay_systems">Electrical relay systems</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Partial_stroke_testing&action=edit&section=10" title="Edit section: Electrical relay systems"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>These systems use an electrical switch to de-energise the solenoid valve and use an electrical relay attached to the actuator to re-energise the solenoid coil when the desired PST point is reached. </p> <div class="mw-heading mw-heading3"><h3 id="Electronic_control_systems">Electronic control systems</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Partial_stroke_testing&action=edit&section=11" title="Edit section: Electronic control systems"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Electronic control systems use a configurable electronic module that connects between the supply from the ESD system and the <a href="/wiki/Solenoid_valve" title="Solenoid valve">solenoid valve</a>. In order to perform a test the timer de-energises the solenoid valve to simulate a shutdown and re-energises the solenoid when the required degree of partial stroke is reached. These systems are fundamentally a miniature <a href="/wiki/Programmable_logic_controller" title="Programmable logic controller">PLC</a> dedicated to the testing of the valve. </p><p>Due to their nature these devices do not actually form part of the safety function and are therefore 100% fail safe. With the addition of a pressure sensor and/or a position sensor for feedback timer systems are also capable of providing intelligent diagnostics in order to diagnose the performance of all components including the valve, actuator and solenoid valves. </p><p>In addition timers are capable of operating with any type of fluid power actuator and can also be used with subsea valves where the solenoid valve is located top-side. </p> <div class="mw-heading mw-heading3"><h3 id="Integrated_solenoid_valve_systems">Integrated solenoid valve systems</h3><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Partial_stroke_testing&action=edit&section=12" title="Edit section: Integrated solenoid valve systems"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <p>Another technique is to embed the control electronics into a solenoid valve enclosure removing the need for additional control boxes. In addition there is no need to change the control schematic as no dedicated components are required. </p> <div class="mw-heading mw-heading2"><h2 id="References">References</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Partial_stroke_testing&action=edit&section=13" title="Edit section: References"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <style data-mw-deduplicate="TemplateStyles:r1239543626">.mw-parser-output .reflist{margin-bottom:0.5em;list-style-type:decimal}@media screen{.mw-parser-output .reflist{font-size:90%}}.mw-parser-output .reflist .references{font-size:100%;margin-bottom:0;list-style-type:inherit}.mw-parser-output .reflist-columns-2{column-width:30em}.mw-parser-output .reflist-columns-3{column-width:25em}.mw-parser-output .reflist-columns{margin-top:0.3em}.mw-parser-output .reflist-columns ol{margin-top:0}.mw-parser-output .reflist-columns li{page-break-inside:avoid;break-inside:avoid-column}.mw-parser-output .reflist-upper-alpha{list-style-type:upper-alpha}.mw-parser-output .reflist-upper-roman{list-style-type:upper-roman}.mw-parser-output .reflist-lower-alpha{list-style-type:lower-alpha}.mw-parser-output .reflist-lower-greek{list-style-type:lower-greek}.mw-parser-output .reflist-lower-roman{list-style-type:lower-roman}</style><div class="reflist"> <div class="mw-references-wrap"><ol class="references"> <li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.isa.org/InTechTemplate.cfm?Section=Article_Index1&template=/ContentManagement/ContentDisplay.cfm&ContentID=73686">Web Exclusive: Valve failure not an option</a> <a rel="nofollow" class="external text" href="https://web.archive.org/web/20110718092829/http://www.isa.org/InTechTemplate.cfm?Section=Article_Index1&template=%2FContentManagement%2FContentDisplay.cfm&ContentID=73686">Archived</a> 2011-07-18 at the <a href="/wiki/Wayback_Machine" title="Wayback Machine">Wayback Machine</a>. ISA (2009-01-01). Retrieved on 2011-05-30.</span> </li> <li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.focus-nuclear.com/actuation/ShowPage.aspx?pageID=564">Partial stroking</a>. Focus-nuclear.com. Retrieved on 2011-05-30.</span> </li> <li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0B5PSPJfG9S5kYTRhMDVhYjAtNTViMy00ZGQ5LWE2ZmItYzY3MjU4NDM3Nzk1&hl=en_US&authkey=CM77sJIP">D-Stop Partial Stroke Test Device. Manual/Local and Remote Operated Mechanical Partial Stroke Valve Testing</a>. Cameron. Docs.google.com. Retrieved on 2011-05-30.</span> </li> <li id="cite_note-4"><span class="mw-cite-backlink"><b><a href="#cite_ref-4">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://www.netherlocks.com/products/partial-stroke-testing/faith-overview/">Netherlocks mechanical PST system FAITH - known as the industry standard.</a> Retrieved on 2013-07-14.</span> </li> </ol></div></div> <div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2><span class="mw-editsection"><span class="mw-editsection-bracket">[</span><a href="/w/index.php?title=Partial_stroke_testing&action=edit&section=14" title="Edit section: External links"><span>edit</span></a><span class="mw-editsection-bracket">]</span></span></div> <ul><li><a rel="nofollow" class="external text" href="http://www.iec.ch/">International Electrotechnical Commission</a></li> <li><a rel="nofollow" class="external text" href="http://www.isa.org/">Instrument Society of America</a></li> <li><a rel="nofollow" class="external text" href="http://www.ascendant-technologies.com/">products/automation-systems/partial-stroke-test-pst-of-actuators</a></li> <li><a rel="nofollow" class="external text" href="https://web.archive.org/web/20121229082755/http://www.paladonsystems.com/index.php/products/pst-controller">Paladon Systems PST Controller</a></li> <li><a rel="nofollow" class="external text" href="http://www.rotork.com/en/product/index/svm">Rotork Smart Valve Monitor</a></li> <li><a rel="nofollow" class="external text" href="http://www.dynatorque.com/dstop/">Dynatorque D-Stop Mechanical Partial Stroke Test Device</a></li> <li><a rel="nofollow" class="external text" href="http://www.foxboro-eckardt.com/en-gb/products/control-valve-positioners/srd991/">Foxboro PST positioner</a></li> <li><a rel="nofollow" class="external text" href="http://www.imi-precision.com/ico4-pst">IMI Precision Engineering - Maxseal ICO4-PST</a></li> <li><a rel="nofollow" class="external text" href="http://www.valcontrols.com/">Val Controls A/S</a></li> <li><a rel="nofollow" class="external text" href="https://www.neles.com/products/valve-controllers/neles-valvguard-vg9000--intelligent-safety-solenoid/">Neles ValvGuard Intelligent Solenoid for ESD Valves and critical ON-OFF valves</a></li></ul>    </div><noscript><img src="https://login.wikimedia.org/wiki/Special:CentralAutoLogin/start?type=1x1&useformat=desktop" alt="" width="1" height="1" style="border: none; position: absolute;"></noscript> <div class="printfooter" data-nosnippet="">Retrieved from "<a dir="ltr" href="https://en.wikipedia.org/w/index.php?title=Partial_stroke_testing&oldid=1199868302">https://en.wikipedia.org/w/index.php?title=Partial_stroke_testing&oldid=1199868302</a>"</div></div> <div id="catlinks" class="catlinks" data-mw="interface"><div id="mw-normal-catlinks" class="mw-normal-catlinks"><a href="/wiki/Help:Category" title="Help:Category">Categories</a>: <ul><li><a href="/wiki/Category:Safety_engineering" title="Category:Safety engineering">Safety engineering</a></li><li><a href="/wiki/Category:Safety_equipment" title="Category:Safety equipment">Safety equipment</a></li><li><a href="/wiki/Category:Valves" title="Category:Valves">Valves</a></li></ul></div><div id="mw-hidden-catlinks" class="mw-hidden-catlinks mw-hidden-cats-hidden">Hidden category: <ul><li><a href="/wiki/Category:Webarchive_template_wayback_links" title="Category:Webarchive template wayback links">Webarchive template wayback links</a></li></ul></div></div> </div> </main> </div> <div class="mw-footer-container"> <footer id="footer" class="mw-footer" > <ul id="footer-info"> <li id="footer-info-lastmod"> This page was last edited on 28 January 2024, at 04:50<span class="anonymous-show"> (UTC)</span>.</li> <li id="footer-info-copyright">Text is available under the <a href="/wiki/Wikipedia:Text_of_the_Creative_Commons_Attribution-ShareAlike_4.0_International_License" title="Wikipedia:Text of the Creative Commons Attribution-ShareAlike 4.0 International License">Creative Commons Attribution-ShareAlike 4.0 License</a>; additional terms may apply. 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