{"id":739,"date":"2024-07-15T12:34:39","date_gmt":"2024-07-15T10:34:39","guid":{"rendered":"https:\/\/www.valfonta.com\/blog\/fire-protection-pressure-relief-valves\/"},"modified":"2026-10-15T12:12:39","modified_gmt":"2026-10-15T10:12:39","slug":"fire-protection-pressure-relief-valves","status":"publish","type":"post","link":"https:\/\/www.valfonta.com\/en\/blog\/fire-protection-pressure-relief-valves\/","title":{"rendered":"Valfonta pressure relief valves for fire protection"},"content":{"rendered":"<div class=\"wp-block-group vf-raiz vf-pl-articulo is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-cat-wrap is-layout-flow wp-block-group-is-layout-flow\"><article class=\"wp-block-group vf-pdp vf-post is-layout-flow wp-block-group-is-layout-flow\"><nav class=\"wp-block-group vf-breadcrumbs vfa-aria-label--Breadcrumbs is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a href=\"\/en\/\">Home<\/a><span class=\"vf-sep\">\u203a<\/span><a href=\"\/en\/blog\/\">Blog<\/a><span class=\"vf-sep\">\u203a<\/span><span aria-current=\"page\">Valfonta pressure relief valves for fire protection<\/span><\/p><\/nav><header class=\"wp-block-group vf-post-head is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-pdp-eyebrow wp-block-paragraph\"><a href=\"\/en\/pressure-relief-valve\/\">Pressure relief valves<\/a><\/p><h1 class=\"wp-block-heading\">Valfonta pressure relief valves for fire protection<\/h1><p class=\"vf-post-meta wp-block-paragraph\"><span>By Valfonta<\/span><span><time datetime=\"2026-09-30\">Updated September 30, 2026<\/time><\/span><span>7 min read<\/span><\/p><\/header><figure class=\"wp-block-image size-full vf-post-hero is-resized\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/gas.jpg\" alt=\"Valfonta pressure relief valves for fire protection\" class=\"wp-image-243\" width=\"1200\" height=\"514\"\/><\/figure><div class=\"wp-block-group vf-post-grid is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-post-body is-layout-flow wp-block-group-is-layout-flow\"><aside class=\"wp-block-group vf-post-summary vfa-aria-label--In%20summary is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t wp-block-paragraph\">In summary<\/p><p class=\"wp-block-paragraph\">A fire protection pressure relief valve prevents overpressure in the network when the pump runs at low flow or overspeed, and returns the excess flow to the suction or to the tank. Valfonta recommends the S3 model, direct-acting with spring and guided plug, with set pressure from 0.5 to 20 barg, AISI 316L internals, and specific approval for fire protection. It is installed on a branch line off the pump discharge, with a pressure gauge upstream and a strainer ahead of it, in horizontal piping. It does not replace a safety valve.<\/p><\/aside><details class=\"wp-block-details vf-post-toc-m is-layout-flow wp-block-details-is-layout-flow\"><summary>Article contents<\/summary><ol class=\"wp-block-list\"><li><a href=\"#valvulas-disenadas-para-aliviar-la-presion-y-garantizar-la-s\">Valves designed to relieve pressure and ensure the safety of the system and its users against a possible fire<\/a><\/li><li><a href=\"#donde-se-instala-la-valvula-de-alivio-en-un-grupo-contra-inc\">Where the relief valve is installed in a fire pump set<\/a><\/li><li><a href=\"#caracteristicas-de-la-valvula-s3\">Features of the S3 valve<\/a><\/li><li><a href=\"#tarado-y-comprobaciones\">Set pressure and checks<\/a><\/li><li><a href=\"#preguntas\">Frequently asked questions<\/a><\/li><\/ol><\/details><h2 class=\"wp-block-heading\" id=\"valvulas-disenadas-para-aliviar-la-presion-y-garantizar-la-s\"><strong>Valves designed to relieve pressure and ensure the safety of the system and its users against a possible fire<\/strong><\/h2><p class=\"wp-block-paragraph\">In this post we will try to clarify and explain in detail all the features of <strong>fire protection pressure relief valves, also called Relief Valves. <\/strong><\/p><p class=\"wp-block-paragraph\">These valves are installed to prevent overpressure in a system or installation when the pump reaches 110% of the motor\u2019s operating speed, or in other words, 121% of the pump\u2019s churn or shutoff pressure\u2014the term used for the pressure at zero flow of the valve\u2014. The general criteria for water networks are in our guide to the <a href=\"\/en\/blog\/water-pressure-relief-valve\/\">pressure relief valve for water<\/a>.<\/p><p class=\"wp-block-paragraph\">Its main function is to prevent overpressure in the fire protection system caused by overspeed.<\/p><figure class=\"wp-block-image size-full is-resized\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/valvula-alivio-presion-s3-s4-perspectiva-400.webp\" alt=\"Fire protection pressure relief valves\" class=\"wp-image-10230\" width=\"400\" height=\"400\" loading=\"lazy\"\/><\/figure><h3 class=\"wp-block-heading\" id=\"nuestras-valvulas-de-alivio-de-presion-contra-incendios-el-m\"><strong>Our fire protection pressure relief valves: the S3 model<\/strong><\/h3><p class=\"wp-block-paragraph\">The<a href=\"\/en\/product\/pressure-relief-valve-s3\/\"><strong> S3 fire protection pressure relief valve<\/strong><\/a> works on the direct-acting principle. That is, when the force resulting from the inlet pressure exceeds the setting force of the spring, the valve opens in proportion to the change in pressure.<\/p><p class=\"wp-block-paragraph\">This spring force is adjusted by means of a special adjusting screw fitted on the valve.<\/p><h4 class=\"wp-block-heading\"><strong>Some of our pressure relief valves<\/strong><\/h4><p class=\"wp-block-paragraph\">It is a model regulated under the ISO 9001 quality system; it must be handled, transported, and stored with care. <\/p><p class=\"wp-block-paragraph\">The most important thing is to protect the valve from adverse external agents such as dirt, moisture, and extreme temperatures.\u00a0<\/p><p class=\"wp-block-paragraph\">It is important to remember that the valves may be too heavy to move by hand; in that case, suitable lifting attachments should be used on the valve body, and it is not at all advisable to attach them to sensitive parts of the valve such as the adjusting screws.<\/p><figure class=\"wp-block-image size-full is-resized\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/Captura-de-pantalla-2021-01-26-a-las-10.09.19-600x380-1.png\" alt=\"Fire protection pressure relief valves\" class=\"wp-image-307\" width=\"600\" height=\"380\" loading=\"lazy\"\/><\/figure><p class=\"wp-block-paragraph\">Other features worth mentioning about this <strong>fire protection pressure relief valve <\/strong>are that the internals are made of AISI 316L stainless steel, it has a guided plug for greater flow stability, a set pressure ranging from 0.5 to 20 barg, and it is suitable for liquids, gases\u2014Group 1 and 2\u2014and steam.<\/p><p class=\"wp-block-paragraph\">To adjust the set pressure, unscrew the cap, carefully remove the O-ring, and turn the adjusting stem clockwise to increase the set pressure, or counterclockwise to decrease it.<\/p><h2 class=\"wp-block-heading\" id=\"donde-se-instala-la-valvula-de-alivio-en-un-grupo-contra-inc\">Where the relief valve is installed in a fire pump set<\/h2><p class=\"wp-block-paragraph\">The relief valve is mounted on a <strong>branch line off the pump discharge<\/strong> that returns to the suction or to the tank, with a pressure gauge upstream. While the pressure is below the set pressure, it remains closed. If the pressure exceeds it, the <a href=\"\/en\/product\/pressure-relief-valve-s3\/\">S3<\/a> opens in proportion to the pressure rise, returns the excess flow, and closes again when the pressure returns to normal.<\/p><ul class=\"wp-block-list\"><li>Pump or equipment that generates the pressure.<\/li><li>Pressure gauge, to check the operating pressure and the opening pressure.<\/li><li>Relief valve, on the branch line.<\/li><li>Discharge to the suction or the tank.<\/li><li>Protected piping network and equipment.<\/li><\/ul><p class=\"wp-block-paragraph\">A strainer should be installed ahead of the valve, and the piping should be cleaned before installation, to protect the seat. The recommended position is in horizontal piping, following the arrow on the body.<\/p><h2 class=\"wp-block-heading\" id=\"caracteristicas-de-la-valvula-s3\">Features of the S3 valve<\/h2><div class=\"wp-block-group vf-tbl-wrap is-layout-flow wp-block-group-is-layout-flow\"><figure class=\"wp-block-table vf-post-table\"><table><thead><tr><th>Feature<\/th><th>Value<\/th><\/tr><\/thead><tbody><tr><th>Principle<\/th><td>Direct-acting, spring-loaded, with guided plug<\/td><\/tr><tr><th>Sizes<\/th><td>DN15 to DN100; DN125 and DN150 on request<\/td><\/tr><tr><th>Set pressure<\/th><td>0.5 to 20 barg, with different spring ranges<\/td><\/tr><tr><th>Pressure rating<\/th><td>PN16 \u2013 PN25 \u2013 PN40 \u00b7 ANSI Class 150 \u2013 300<\/td><\/tr><tr><th>Kv<\/th><td>From 3.5 m\u00b3\/h (DN15) to 130 m\u00b3\/h (DN100)<\/td><\/tr><tr><th>Leakage class<\/th><td>IV (metal-to-metal) or VI (PTFE + graphite seat)<\/td><\/tr><tr><th>Body<\/th><td>GP240GH carbon steel or A351 CF3M stainless; on request, RG10 bronze, duplex, or super duplex<\/td><\/tr><tr><th>Internals<\/th><td>Stainless steel AISI 316L<\/td><\/tr><tr><th>Connections<\/th><td>EN and ANSI flanges \u00b7 BSP or NPT thread from \u00bd\u2033 to 2\u2033<\/td><\/tr><tr><th>Options<\/th><td>Handwheel adjustment \u00b7 special plugs and gaskets<\/td><\/tr><\/tbody><\/table><\/figure><\/div><p class=\"vf-anote wp-block-paragraph\">Data from the S3 manual and datasheet.<\/p><h2 class=\"wp-block-heading\" id=\"tarado-y-comprobaciones\">Set pressure and checks<\/h2><p class=\"wp-block-paragraph\">Valfonta supplies the valve adjusted to the set pressure specified in the order. If it needs to be corrected, remove the cap (15) and the O-ring (16) and turn the adjusting stem (13): turning it clockwise compresses the spring and increases the set pressure; counterclockwise, it decreases. With the handwheel option, simply turn the handwheel. Then refit the O-ring and the cap.<\/p><p class=\"wp-block-paragraph\">At start-up, open the isolation valves slowly, the inlet valve first, to avoid water hammer. Periodically check that the valve opens at the intended value: we explain this in why you should audit the set pressure of relief valves. An oversized valve tends to open and close abruptly; see <a href=\"\/en\/blog\/chattering-in-pressure-relief-valves\/\">chattering in relief valves<\/a>.<\/p><p class=\"wp-block-paragraph\">The S3 has specific approval for fire protection installations. If your project requires it, ask us for the certificate with the quote and tell us which regulations the installation must meet. In addition, it is manufactured under an ISO 9001 quality system and, depending on size and pressure, under module D1 of the Pressure Equipment Directive: see <a href=\"\/en\/certificates\/\">certificates<\/a>.<\/p><p class=\"wp-block-paragraph\">If you are comparing models, our <a href=\"\/en\/pressure-relief-valve\/\">pressure relief valves<\/a> page has the table with the seven models in the range.<\/p><h4 class=\"wp-block-heading\"><strong>Feel free to ask us for personalized advice on choosing your fire protection pressure relief valve <\/strong><\/h4><p class=\"wp-block-paragraph\">We have spent many years working as manufacturers of <a href=\"\/en\/pressure-relief-valve\/\"><strong>pressure relief,<\/strong><\/a> <a href=\"\/en\/pressure-reducing-valves\/\"><strong>pressure reducing,<\/strong><\/a> <a href=\"\/en\/control-valve\/\"><strong> control,<\/strong><\/a> and <a href=\"\/en\/safety-valves\/\"><strong>safety<\/strong><\/a> valves. We also have a dedicated line of steam and liquid <a href=\"\/en\/liquid-steam-ejectors\/\"><strong>ejectors <\/strong><\/a>and<a href=\"\/en\/liquids-steam-injector\/\"><strong> injectors<\/strong><\/a>.\u00a0<\/p><p class=\"wp-block-paragraph\">If you are not familiar with aspects such as how they work, their terminology, or their technical applications, components of this type can be somewhat difficult to choose.<\/p><p class=\"wp-block-paragraph\">To receive direct, personalized advice from one of our specialized technicians, simply fill out our <a href=\"\/en\/contact\/\"><strong>contact form<\/strong><\/a>. You can also call us at <a href=\"https:\/\/www.google.com\/search?q=valfonta&amp;rlz=1C5CHFA_enES938ES938&amp;oq=valfonta&amp;aqs=chrome..69i57j0i10i19j0i19j69i60l2j69i61j69i60j69i65.3407j1j4&amp;sourceid=chrome&amp;ie=UTF-8#\" rel=\"noopener\" target=\"_blank\"><strong>933 72 08 88<\/strong><\/a> or email us at <a href=\"mailto:valfonta@valfonta.com\"><strong>valfonta@valfonta.com<\/strong><\/a><strong>. <\/strong><\/p><p class=\"wp-block-paragraph\">We will answer all your questions, provide detailed and valuable information, and guide you throughout the selection process. This is, without a doubt, one of the most important parts of our daily work.<\/p><figure class=\"wp-block-image size-full is-resized\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/logo.png\" alt=\"Steam pressure reducing valve\" class=\"wp-image-254\" width=\"332\" height=\"83\" loading=\"lazy\"\/><\/figure><section id=\"preguntas\" class=\"wp-block-group vf-post-faq is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">Frequently asked questions<\/h2><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>What is a relief valve on a fire pump for?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">To prevent the network pressure from exceeding the set value when the pump runs at low flow or overspeed. The valve opens, returns the excess flow to the suction or to the tank, and closes when the pressure returns to its value.<\/p><\/div><\/details><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>What set pressure range does the S3 have?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">From 0.5 to 20 barg, with different springs. In DN15 and DN20, for example, the standard ranges are 1 to 6, 4 to 12, and 8 to 16 barg; the 15 to 25 barg range is available on request.<\/p><\/div><\/details><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Does a relief valve replace a safety valve?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">No. The relief valve opens proportionally to maintain the pressure; it is not a safety accessory. If the installation needs overpressure protection, a <a href=\"\/en\/safety-valves\/\">safety valve<\/a> must also be installed. See <a href=\"\/en\/blog\/what-difference-between-safety-valve-and-relief-valve\/\">the difference between a safety valve and a relief valve<\/a>.<\/p><\/div><\/details><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Is the S3 approved for fire protection installations?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">Yes, it has specific approval for fire protection. Ask us for the certificate along with the quote.<\/p><\/div><\/details><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>What seat do I need if I want full tightness?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">The S3 offers leakage class IV with a metal-to-metal seat and class VI with a PTFE + graphite seat.<\/p><\/div><\/details><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>What information should I send to order the valve?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">The fluid and its temperature, the set pressure and the normal operating pressure, the flow it must relieve, the size, the body material and the connection type, and the regulations the installation must meet. You can send them via <a href=\"\/en\/contact\/\">contact<\/a>.<\/p><\/div><\/details><\/section><\/div><aside class=\"wp-block-group vf-post-aside is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-post-sticky is-layout-flow wp-block-group-is-layout-flow\"><nav class=\"wp-block-group vf-post-toc vfa-aria-label--Article%20contents is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">In this article<\/p><ol class=\"wp-block-list\"><li><a href=\"#valvulas-disenadas-para-aliviar-la-presion-y-garantizar-la-s\">Valves designed to relieve pressure and ensure the safety of the system and its users against a possible fire<\/a><\/li><li><a href=\"#donde-se-instala-la-valvula-de-alivio-en-un-grupo-contra-inc\">Where the relief valve is installed in a fire pump set<\/a><\/li><li><a href=\"#caracteristicas-de-la-valvula-s3\">Features of the S3 valve<\/a><\/li><li><a href=\"#tarado-y-comprobaciones\">Set pressure and checks<\/a><\/li><li><a href=\"#preguntas\">Frequently asked questions<\/a><\/li><\/ol><\/nav><div class=\"wp-block-group vf-post-cta is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t wp-block-paragraph\">Do you need a pressure relief or excess pressure valve?<\/p><p class=\"wp-block-paragraph\">We help you choose the right model and size for your installation.<\/p><p class=\"vf-envolt wp-block-paragraph\"><a class=\"vf-btn vf-btn--pri\" href=\"#contactar\">Request a quote<\/a><\/p><p class=\"vf-envolt wp-block-paragraph\"><a class=\"vf-btn vf-btn--sec\" href=\"\/en\/pressure-relief-valve\/\">View pressure relief valves<\/a><\/p><p class=\"vf-tel wp-block-paragraph\">Or call <a href=\"tel:+34933720888\">933 720 888<\/a><\/p><\/div><\/div><\/aside><\/div><section id=\"valvulas\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">Related valves<\/h2><ul class=\"vf-rel wp-block-list\"><li><a href=\"\/en\/product\/pressure-relief-valve-s3\/\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/valvula-alivio-presion-s3-s4-perspectiva-400.webp\" alt=\"S3 pressure relief valve\" class=\"wp-image-10230\" width=\"300\" height=\"300\" loading=\"lazy\"><b>S3 pressure relief valve<\/b><span>From DN15 to DN150, PN40, set pressure up to 20 barg and 220 \u00b0C.<\/span><\/a><\/li><li><a href=\"\/en\/pressure-reducing-valves\/\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/Valvula-reductora-plateada.webp\" alt=\"Pressure reducing valves\" class=\"wp-image-228\" width=\"300\" height=\"300\" loading=\"lazy\"><b>Pressure reducing valves<\/b><span>Valfonta pressure reducing valves: 8 models from DN8 to DN150 and up to 40 bar for steam, water, air, and gases.<\/span><\/a><\/li><li><a href=\"\/en\/control-valve\/\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/valvula-de-control-scaled-1.jpg\" alt=\"Control valves\" class=\"wp-image-161\" width=\"300\" height=\"300\" loading=\"lazy\"><b>Control valves<\/b><span>Valfonta C1 control valve: globe valve with pneumatic actuator, DN15 to DN100, PN40, and Kv up to 130 m\u00b3\/h.<\/span><\/a><\/li><\/ul><p class=\"vf-post-more wp-block-paragraph\"><a href=\"\/en\/pressure-relief-valve\/\">View all pressure relief valves \u2192<\/a><\/p><\/section><section id=\"articulos\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">Related articles<\/h2><div class=\"wp-block-group vf-post-cards vf-t-ul is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-amb-enllac is-layout-flow wp-block-group-is-layout-flow\"><figure class=\"wp-block-image vf-img-suelta\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/valvula-alivio-presion.png\" alt=\"\" class=\"wp-image-233\" width=\"400\" height=\"225\" loading=\"lazy\"><\/figure><div class=\"wp-block-group vf-in is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><small>Pressure relief valves<\/small><b>Discover the Valfonta Model S3 hydraulic pressure relief valve<\/b><span>5 min read<\/span><\/p><\/div><p class=\"vf-enllac wp-block-paragraph\"><a class=\"vf-enllac-estirat\" href=\"\/en\/blog\/hydraulic-pressure-relief-valve\/\" aria-label=\"Pressure relief valves Discover the Valfonta Model S3 hydraulic pressure relief valve 5 min read\"><\/a><\/p><\/div><\/div><div class=\"wp-block-group vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-amb-enllac is-layout-flow wp-block-group-is-layout-flow\"><figure class=\"wp-block-image vf-img-suelta\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/chattering-valvulas-alivio.webp\" alt=\"\" class=\"wp-image-222\" width=\"400\" height=\"225\" loading=\"lazy\"><\/figure><div class=\"wp-block-group vf-in is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><small>Pressure relief valves<\/small><b>How to prevent \u201cchattering\u201d (vibration) in pressure relief valves<\/b><span>13 min read<\/span><\/p><\/div><p class=\"vf-enllac wp-block-paragraph\"><a class=\"vf-enllac-estirat\" href=\"\/en\/blog\/chattering-in-pressure-relief-valves\/\" aria-label=\"Pressure relief valves How to prevent \u201cchattering\u201d (vibration) in pressure relief valves 13 min read\"><\/a><\/p><\/div><\/div><div class=\"wp-block-group vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-amb-enllac is-layout-flow wp-block-group-is-layout-flow\"><figure class=\"wp-block-image vf-img-suelta\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/valvula-alivio-presion.png\" alt=\"\" class=\"wp-image-233\" width=\"400\" height=\"225\" loading=\"lazy\"><\/figure><div class=\"wp-block-group vf-in is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><small>Pressure relief valves<\/small><b>What are the main features of a pneumatic pressure relief valve?<\/b><span>5 min read<\/span><\/p><\/div><p class=\"vf-enllac wp-block-paragraph\"><a class=\"vf-enllac-estirat\" href=\"\/en\/blog\/pneumatic-pressure-relief-valve\/\" aria-label=\"Pressure relief valves What are the main features of a pneumatic pressure relief valve? 5 min read\"><\/a><\/p><\/div><\/div><\/div><\/section><section id=\"contactar\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-quote is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">Can we help with your installation?<\/h2><p class=\"wp-block-paragraph\">Tell us the fluid, the inlet and outlet pressures, the temperature, and the flow rate, and we will recommend the right valve.<\/p><p class=\"vf-pdp-contact wp-block-paragraph\">You can also call <a href=\"tel:+34933720888\">933 720 888<\/a> or email <a href=\"mailto:valfonta@valfonta.com\">valfonta@valfonta.com<\/a>.<\/p><\/div>\n<div class=\"wpcf7 no-js\" id=\"wpcf7-f535-o1\" lang=\"en-US\" dir=\"ltr\" data-wpcf7-id=\"535\">\n<div class=\"screen-reader-response\"><p role=\"status\" aria-live=\"polite\" aria-atomic=\"true\"><\/p> <ul><\/ul><\/div>\n<form action=\"\/en\/wp-json\/wp\/v2\/posts\/739#wpcf7-f535-o1\" method=\"post\" class=\"wpcf7-form init vf-form wpcf7-acceptance-as-validation\" aria-label=\"Contact form\" novalidate=\"novalidate\" data-status=\"init\" toolname=\"consulta_contacto\" tooldescription=\"Send an enquiry to Valfonta, industrial valve manufacturer; a member of the team will reply.\">\n<fieldset class=\"hidden-fields-container\"><input type=\"hidden\" name=\"_wpcf7\" value=\"535\" \/><input type=\"hidden\" name=\"_wpcf7_version\" value=\"6.2.3\" \/><input type=\"hidden\" name=\"_wpcf7_locale\" value=\"en_US\" \/><input type=\"hidden\" name=\"_wpcf7_unit_tag\" value=\"wpcf7-f535-o1\" \/><input type=\"hidden\" name=\"_wpcf7_container_post\" value=\"0\" \/><input type=\"hidden\" name=\"_wpcf7_posted_data_hash\" value=\"\" \/><input type=\"hidden\" name=\"_vf_t\" value=\"1792702976.846fb148dc2ba259\" \/>\n<\/fieldset>\n<label>Name *<span class=\"wpcf7-form-control-wrap\" data-name=\"nombre\"><input size=\"40\" maxlength=\"400\" class=\"wpcf7-form-control wpcf7-text wpcf7-validates-as-required\" autocomplete=\"name\" aria-required=\"true\" aria-invalid=\"false\" value=\"\" type=\"text\" name=\"nombre\" \/><\/span><\/label><label>Company<span class=\"wpcf7-form-control-wrap\" data-name=\"empresa\"><input size=\"40\" maxlength=\"400\" class=\"wpcf7-form-control wpcf7-text\" autocomplete=\"organization\" aria-invalid=\"false\" value=\"\" type=\"text\" name=\"empresa\" 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valve\">Technical advice on choosing a valve<\/option><option value=\"Spare parts or repair\">Spare parts or repair<\/option><option value=\"Documentation or certificates\">Documentation or certificates<\/option><option value=\"Other\">Other<\/option><\/select><\/span><\/label><label class=\"vf-full\">Message *<span class=\"wpcf7-form-control-wrap\" data-name=\"mensaje\"><textarea cols=\"40\" rows=\"5\" maxlength=\"2000\" class=\"wpcf7-form-control wpcf7-textarea wpcf7-validates-as-required\" aria-required=\"true\" aria-invalid=\"false\" placeholder=\"Tell us what you need: fluid, pressures, flow rate, model, or serial number\u2026\" name=\"mensaje\"><\/textarea><\/span><\/label><label class=\"vf-chk vf-full\"><span class=\"wpcf7-form-control-wrap\" data-name=\"privacidad\"><span class=\"wpcf7-form-control wpcf7-acceptance\"><span class=\"wpcf7-list-item\"><input type=\"checkbox\" name=\"privacidad\" value=\"1\" aria-invalid=\"false\" \/><\/span><\/span><\/span> <span>I have read and accept the <a href=\"\/en\/privacy-policy\/\">privacy policy<\/a> *<\/span><\/label><input class=\"wpcf7-form-control wpcf7-submit has-spinner vf-btn vf-btn--pri\" type=\"submit\" value=\"Send message\" \/><span class=\"vf-hp\" aria-hidden=\"true\"><label>Web <input type=\"text\" name=\"vf_web\" value=\"\" tabindex=\"-1\" autocomplete=\"off\" toolparamdescription=\"Campo de control: d\u00e9jalo vac\u00edo\"><\/label><\/span><div class=\"wpcf7-response-output\" aria-hidden=\"true\"><\/div>\n<\/form>\n<\/div>\n\n<\/div><\/section><div class=\"wp-block-group vf-pdp-bar is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a class=\"vf-btn vf-btn--sec\" href=\"tel:+34933720888\">Call<\/a><a class=\"vf-btn vf-btn--pri\" href=\"#contactar\">Request a quote<\/a><\/p><\/div><\/article><\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>A fire protection pressure relief valve prevents overpressure in the network when the pump runs at low flow or overspeeds, and returns the excess flow to the suction side or the tank.<\/p>\n","protected":false},"author":1,"featured_media":243,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_generate-full-width-content":"true","_generate-disable-headline":"true","rank_math_title":"Fire protection pressure relief valves | Valfonta","rank_math_description":"How to install and set a relief valve in a fire pump system, and features of the Valfonta S3 pressure relief valve.","rank_math_focus_keyword":"","vf_jsonld":"[{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Organization\",\"@id\":\"https:\/\/www.valfonta.com\/#organization\",\"name\":\"Valfonta\",\"legalName\":\"Val Fonta, 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Les Guixeres\",\"postalCode\":\"08915\",\"addressLocality\":\"Badalona\",\"addressRegion\":\"Barcelona\",\"addressCountry\":\"ES\"},\"description\":\"Design, manufacture, and sale of pressure reducing valves, pressure relief valves, and control valves.\"},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.valfonta.com\/#website\",\"url\":\"https:\/\/www.valfonta.com\/en\/\",\"name\":\"Valfonta\",\"publisher\":{\"@id\":\"https:\/\/www.valfonta.com\/#organization\"},\"inLanguage\":\"en\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.valfonta.com\/en\/blog\/fire-protection-pressure-relief-valves\/#webpage\",\"url\":\"https:\/\/www.valfonta.com\/en\/blog\/fire-protection-pressure-relief-valves\/\",\"name\":\"Fire protection pressure relief valves | Valfonta\",\"description\":\"How to install and set a relief valve in a fire pump system, and features of the Valfonta S3 pressure relief valve.\",\"isPartOf\":{\"@id\":\"https:\/\/www.valfonta.com\/#website\"},\"about\":{\"@id\":\"https:\/\/www.valfonta.com\/#organization\"},\"inLanguage\":\"en\",\"datePublished\":\"2024-07-15T12:34:39+02:00\",\"dateModified\":\"2026-09-30T12:00:00+02:00\",\"primaryImageOfPage\":{\"@id\":\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/gas.jpg\"},\"breadcrumb\":{\"@id\":\"https:\/\/www.valfonta.com\/en\/blog\/fire-protection-pressure-relief-valves\/#breadcrumb\"}},{\"@type\":\"ImageObject\",\"@id\":\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/gas.jpg\",\"url\":\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/gas.jpg\",\"caption\":\"Valfonta pressure relief valves for fire protection\",\"inLanguage\":\"en\"},{\"@type\":\"ImageObject\",\"@id\":\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/gas.jpg\",\"url\":\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/gas.jpg\",\"width\":\"1000\",\"height\":\"1000\",\"caption\":\"Pressure relief valves in fire protection systems\",\"inLanguage\":\"en\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.valfonta.com\/en\/blog\/fire-protection-pressure-relief-valves\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.valfonta.com\/en\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Blog\",\"item\":\"https:\/\/www.valfonta.com\/en\/blog\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Valfonta pressure relief valves for fire protection\",\"item\":\"https:\/\/www.valfonta.com\/en\/blog\/fire-protection-pressure-relief-valves\/\"}]},{\"@type\":\"BlogPosting\",\"keywords\":\"fire protection pressure relief valves\",\"datePublished\":\"2024-07-15T12:34:39+02:00\",\"dateModified\":\"2026-09-30T12:00:00+02:00\",\"articleSection\":\"Pressure relief valves\",\"publisher\":{\"@id\":\"https:\/\/www.valfonta.com\/#organization\"},\"@id\":\"https:\/\/www.valfonta.com\/en\/blog\/fire-protection-pressure-relief-valves\/#richSnippet\",\"isPartOf\":{\"@id\":\"https:\/\/www.valfonta.com\/en\/blog\/fire-protection-pressure-relief-valves\/#webpage\"},\"image\":{\"@id\":\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/gas.jpg\"},\"inLanguage\":\"en\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.valfonta.com\/en\/blog\/fire-protection-pressure-relief-valves\/#webpage\"},\"headline\":\"Valfonta pressure relief valves for fire protection\",\"name\":\"Fire protection pressure relief valves | Valfonta\",\"description\":\"How to install and set a relief valve in a fire pump system, and features of the Valfonta S3 pressure relief valve.\",\"author\":{\"@id\":\"https:\/\/www.valfonta.com\/#organization\"},\"abstract\":\"A fire protection pressure relief valve prevents overpressure in the network when the pump runs at low flow or overspeed, and returns the excess flow to the suction or to the tank. Valfonta recommends the S3 model, direct-acting with spring and guided plug, with set pressure from 0.5 to 20 barg, AISI 316L internals, and specific approval for fire protection. It is installed on a branch line off the pump discharge, with a pressure gauge upstream and a strainer ahead of it, in horizontal piping. It does not replace a safety valve.\"},{\"@type\":\"FAQPage\",\"@id\":\"https:\/\/www.valfonta.com\/en\/blog\/fire-protection-pressure-relief-valves\/#faq\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"What is a relief valve on a fire pump for?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"To prevent the network pressure from exceeding the set value when the pump runs at low flow or overspeed. The valve opens, returns the excess flow to the suction or to the tank, and closes when the pressure returns to its value.\"}},{\"@type\":\"Question\",\"name\":\"What set pressure range does the S3 have?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"From 0.5 to 20 barg, with different springs. In DN15 and DN20, for example, the standard ranges are 1 to 6, 4 to 12, and 8 to 16 barg; the 15 to 25 barg range is available on request.\"}},{\"@type\":\"Question\",\"name\":\"Does a relief valve replace a safety valve?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No. The relief valve opens proportionally to maintain the pressure; it is not a safety accessory. If the installation needs overpressure protection, a safety valve must also be installed. See the difference between a safety valve and a relief valve.\"}},{\"@type\":\"Question\",\"name\":\"Is the S3 approved for fire protection installations?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes, it has specific approval for fire protection. Ask us for the certificate along with the quote.\"}},{\"@type\":\"Question\",\"name\":\"What seat do I need if I want full tightness?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"The S3 offers leakage class IV with a metal-to-metal seat and class VI with a PTFE + graphite seat.\"}},{\"@type\":\"Question\",\"name\":\"What information should I send to order the valve?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"The fluid and its temperature, the set pressure and the normal operating pressure, the flow it must relieve, the size, the body material and the connection type, and the regulations the installation must meet. You can send them via contact.\"}}]}]}]","footnotes":"","_vg_translation_of":"504","_vg_lang":"en","_vg_wpml_state":"{\"lang\":\"en\",\"trid\":\"704\",\"src\":\"es\"}"},"categories":[37],"tags":[],"class_list":["post-739","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-relief-and-safety"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/posts\/739","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/comments?post=739"}],"version-history":[{"count":3,"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/posts\/739\/revisions"}],"predecessor-version":[{"id":10293,"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/posts\/739\/revisions\/10293"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/media\/243"}],"wp:attachment":[{"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/media?parent=739"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/categories?post=739"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/tags?post=739"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}