{"id":624,"date":"2026-10-02T13:11:11","date_gmt":"2026-10-02T11:11:11","guid":{"rendered":"https:\/\/www.valfonta.com\/pressure-relief-valve\/"},"modified":"2026-10-20T10:17:21","modified_gmt":"2026-10-20T08:17:21","slug":"pressure-relief-valve","status":"publish","type":"page","link":"https:\/\/www.valfonta.com\/en\/pressure-relief-valve\/","title":{"rendered":"Pressure relief valves"},"content":{"rendered":"<div class=\"wp-block-group vf-raiz vf-pl-hub 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-cat vf-c2 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><span aria-current=\"page\">Pressure relief valves<\/span><\/p><\/nav><div class=\"wp-block-group vf-cat-hero vf-c2-hero is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-pdp-eyebrow wp-block-paragraph\">Designed and manufactured in Badalona since 1962<\/p><h1 class=\"wp-block-heading\">Pressure relief valves<\/h1><p class=\"vf-lead wp-block-paragraph\">They hold upstream pressure at the set pressure: when it is exceeded, they open in proportion to the rise and discharge the excess, with no auxiliary power. They are also called <strong>excess pressure valves<\/strong>. Six spring, piston, diaphragm, or bellows models for steam, water, oil, compressed air, and gases.<\/p><ul class=\"vf-pdp-keys wp-block-list\"><li><span>Sizes<\/span><b>DN15 to DN150<\/b><\/li><li><span>Set pressure<\/span><b>0.01 to 20 barg<\/b><\/li><li><span>Pressure rating<\/span><b>PN25 \u2013 PN40<\/b><\/li><li><span>Temperature<\/span><b>up to 220 \u00b0C<\/b><\/li><\/ul><div class=\"wp-block-group vf-pdp-cta is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a class=\"vf-btn vf-btn--pri\" href=\"#solicitar\">Request a quote<\/a><a class=\"vf-btn vf-btn--sec\" href=\"#modelos\" data-vf-view-go=\"table\">Compare models<\/a><\/p><\/div><p class=\"vf-pdp-contact wp-block-paragraph\">Questions about the set pressure or the model? Call <a href=\"tel:+34933720888\">933 720 888<\/a> or email <a href=\"mailto:valfonta@valfonta.com\">valfonta@valfonta.com<\/a>.<\/p><\/div><div class=\"wp-block-group vf-c2-finder vfa-role--group vfa-aria-labelledby--vf-c2-fh is-layout-flow wp-block-group-is-layout-flow\"><p id=\"vf-c2-fh\" class=\"vf-fh wp-block-paragraph\">Find your relief valve<\/p><div class=\"wp-block-group vf-grp is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><span class=\"vf-lab\">Fluid<\/span><\/p><div class=\"wp-block-group vf-chips is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><button type=\"button\" class=\"vf-chip\" data-vf-filter=\"fl\" data-v=\"vapor\" aria-pressed=\"false\">Steam<\/button><button type=\"button\" class=\"vf-chip\" data-vf-filter=\"fl\" data-v=\"liq\" aria-pressed=\"false\">Water and liquids<\/button><button type=\"button\" class=\"vf-chip\" data-vf-filter=\"fl\" data-v=\"gas\" aria-pressed=\"false\">Air and gases<\/button><\/p><\/div><\/div><div class=\"wp-block-group vf-grp is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><span class=\"vf-lab\">Set pressure<\/span><\/p><div class=\"wp-block-group vf-chips is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><button type=\"button\" class=\"vf-chip\" data-vf-filter=\"p\" data-v=\"0-0.5\" data-m=\"s\" aria-pressed=\"false\">Under 0.5 barg<\/button><button type=\"button\" class=\"vf-chip\" data-vf-filter=\"p\" data-v=\"0.5-10\" data-m=\"s\" aria-pressed=\"false\">0.5 to 10 barg<\/button><button type=\"button\" class=\"vf-chip\" data-vf-filter=\"p\" data-v=\"10-20\" data-m=\"s\" aria-pressed=\"false\">Over 10 barg<\/button><\/p><\/div><\/div><div class=\"wp-block-group vf-grp is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><span class=\"vf-lab\">Size<\/span><\/p><div class=\"wp-block-group vf-chips is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><button type=\"button\" class=\"vf-chip\" data-vf-filter=\"dn\" data-v=\"0-25\" aria-pressed=\"false\">Up to DN25<\/button><button type=\"button\" class=\"vf-chip\" data-vf-filter=\"dn\" data-v=\"32-50\" aria-pressed=\"false\">DN32 to DN50<\/button><button type=\"button\" class=\"vf-chip\" data-vf-filter=\"dn\" data-v=\"65-150\" aria-pressed=\"false\">DN65 to DN150<\/button><\/p><\/div><\/div><div class=\"wp-block-group vf-fbar is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a class=\"vf-btn vf-btn--pri\" href=\"#modelos\"><span>View <b data-vf-count=\"\">6<\/b> <span data-vf-count-txt=\"\" data-one=\"model\" data-many=\"models\">models<\/span><\/span><\/a><button type=\"button\" class=\"vf-reset\" data-vf-reset=\"\" hidden>Clear filters<\/button><\/p><\/div><\/div><\/div><ul class=\"vf-pdp-trust wp-block-list\"><li>In-house design and manufacturing in Badalona<\/li><li>Set pressures from 10 mbar to 20 barg<\/li><li>No auxiliary power: they run on the process fluid itself<\/li><li>Genuine spare parts for each model<\/li><\/ul><nav class=\"wp-block-group vf-pdp-nav vfa-aria-label--Datasheet%20contents is-layout-flow wp-block-group-is-layout-flow\"><ul class=\"wp-block-list\"><li><a href=\"#modelos\">Models<\/a><\/li><li><a href=\"#como-funciona\">How it works<\/a><\/li><li><a href=\"#diferencias\">Relief, safety, or reducing<\/a><\/li><li><a href=\"#aplicaciones\">Applications<\/a><\/li><li><a href=\"#preguntas\">FAQ<\/a><\/li><li><a href=\"#solicitar\">Request a quote<\/a><\/li><\/ul><\/nav><section id=\"modelos\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">Pressure relief valve models<\/h2><p class=\"vf-c2-intro wp-block-paragraph\">Filter with the search tool in the header or switch to the comparison table. Each product page includes the complete specifications, the exploded view, installation, and PDFs.<\/p><div class=\"wp-block-group vf-c2-bar is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-count vfa-aria-live--polite wp-block-paragraph\"><b data-vf-count=\"\">6<\/b> <span data-vf-count-txt=\"\" data-one=\"model\" data-many=\"models\" data-fit=\"1\">models<\/span><\/p><p class=\"vf-envolt wp-block-paragraph\"><button type=\"button\" class=\"vf-reset\" data-vf-reset=\"\" hidden>Clear filters<\/button><\/p><div class=\"wp-block-group vf-view vfa-role--tablist vfa-aria-label--View is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><button type=\"button\" role=\"tab\" aria-selected=\"true\" data-vf-view=\"cards\">Cards<\/button><button type=\"button\" role=\"tab\" aria-selected=\"false\" data-vf-view=\"table\">Comparison table<\/button><\/p><\/div><\/div><div class=\"wp-block-group vf-c2-cardsview is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-c2-group vfd-group--pequenas is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-ghead is-layout-flow wp-block-group-is-layout-flow\"><h3 class=\"wp-block-heading\">Small lines: DN15 to DN25<\/h3><p class=\"wp-block-paragraph\">Compact, in 316L stainless steel, threaded or flanged. Set pressures from 10 mbar (PRV55) to 12 barg (PRV54).<\/p><\/div><div class=\"wp-block-group vf-c2-cards vf-t-ul is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-c2-card vfd-vf-item--p vfd-fl--liq%20gas vfd-pmin--0.5 vfd-pmax--10 vfd-dnmin--15 vfd-dnmax--25 vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-img is-layout-flow wp-block-group-is-layout-flow\"><figure class=\"wp-block-image vf-img-suelta\"><a href=\"\/en\/product\/pressure-excess-valve-prv53\/\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/ok-PRV30-44-700x700-1.jpg\" alt=\"PRV53 excess pressure valve in 316L stainless steel with threaded connection\" class=\"wp-image-181\" width=\"160\" height=\"160\" loading=\"lazy\"><\/a><\/figure><\/div><div class=\"wp-block-group vf-body is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-tag wp-block-paragraph\">Piston<\/p><h3 class=\"wp-block-heading\"><a href=\"\/en\/product\/pressure-excess-valve-prv53\/\">PRV53<\/a><\/h3><p class=\"vf-sub wp-block-paragraph\">Piston excess pressure valve in 316L stainless steel.<\/p><div class=\"wp-block-group vf-t-dl is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Set pressure<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">0.5 to 10 barg <small>15 on request<\/small><\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Size<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">DN15 to DN25<\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Temperature<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">up to 150 \u00b0C <small>depending on gaskets<\/small><\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Steam<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">No<\/p><\/div><\/div><p class=\"vf-fit wp-block-paragraph\"><b>Choose it if<\/b> you work with water, fuel oil, compressed air, nitrogen, or other inert gases.<\/p><div class=\"wp-block-group vf-act is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a class=\"vf-btn vf-btn--sec\" href=\"\/en\/product\/pressure-excess-valve-prv53\/\">View product<\/a><a class=\"vf-btn vf-btn--pri\" href=\"#solicitar\" data-vf-model=\"PRV53 valve\">Request a quote<\/a><\/p><\/div><\/div><\/div><div class=\"wp-block-group vf-c2-card vfd-vf-item--p vfd-fl--vapor%20liq%20gas vfd-pmin--0.5 vfd-pmax--12 vfd-dnmin--15 vfd-dnmax--25 vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-img is-layout-flow wp-block-group-is-layout-flow\"><figure class=\"wp-block-image vf-img-suelta\"><a href=\"\/en\/product\/pressure-excess-valve-prv54\/\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/ok-PRV30-44-700x700-1.jpg\" alt=\"PRV54 excess pressure valve in 316L stainless steel with bellows, for steam\" class=\"wp-image-181\" width=\"160\" height=\"160\" loading=\"lazy\"><\/a><\/figure><\/div><div class=\"wp-block-group vf-body is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-tag wp-block-paragraph\">Bellows \u00b7 steam<\/p><h3 class=\"wp-block-heading\"><a href=\"\/en\/product\/pressure-excess-valve-prv54\/\">PRV54<\/a><\/h3><p class=\"vf-sub wp-block-paragraph\">Bellows-balanced excess pressure valve in 316L stainless steel.<\/p><div class=\"wp-block-group vf-t-dl is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Set pressure<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">0.5 to 12 barg<\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Size<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">DN15 to DN25<\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Temperature<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">up to 210 \u00b0C <small>depending on gaskets<\/small><\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Steam<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">Yes<\/p><\/div><\/div><p class=\"vf-fit wp-block-paragraph\"><b>Choose it if<\/b> the fluid is steam, or liquids and gases above 150 \u00b0C.<\/p><div class=\"wp-block-group vf-act is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a class=\"vf-btn vf-btn--sec\" href=\"\/en\/product\/pressure-excess-valve-prv54\/\">View product<\/a><a class=\"vf-btn vf-btn--pri\" href=\"#solicitar\" data-vf-model=\"PRV54 valve\">Request a quote<\/a><\/p><\/div><\/div><\/div><div class=\"wp-block-group vf-c2-card vfd-vf-item--p vfd-fl--vapor%20liq%20gas vfd-pmin--0.01 vfd-pmax--8 vfd-dnmin--15 vfd-dnmax--25 vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-img is-layout-flow wp-block-group-is-layout-flow\"><figure class=\"wp-block-image vf-img-suelta\"><a href=\"\/en\/product\/excess-pressure-valve-model-prv55\/\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/ok-PRV45-55-700x700-1.jpg\" alt=\"PRV55 excess pressure valve with diaphragm actuator and 316L stainless steel body\" class=\"wp-image-191\" width=\"160\" height=\"160\" loading=\"lazy\"><\/a><\/figure><\/div><div class=\"wp-block-group vf-body is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-tag wp-block-paragraph\">Diaphragm \u00b7 low pressure<\/p><h3 class=\"wp-block-heading\"><a href=\"\/en\/product\/excess-pressure-valve-model-prv55\/\">PRV55<\/a><\/h3><p class=\"vf-sub wp-block-paragraph\">Diaphragm excess pressure valve in 316L stainless steel.<\/p><div class=\"wp-block-group vf-t-dl is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Set pressure<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">0.01 to 8 barg<\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Size<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">DN15 to DN25<\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Temperature<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">\u221210 to 150 \u00b0C <small>with Viton gaskets<\/small><\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Steam<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">Yes<\/p><\/div><\/div><p class=\"vf-fit wp-block-paragraph\"><b>Choose it if<\/b> you need very low set pressures, from 10 mbar, with gases, liquids, or steam.<\/p><div class=\"wp-block-group vf-act is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a class=\"vf-btn vf-btn--sec\" href=\"\/en\/product\/excess-pressure-valve-model-prv55\/\">View product<\/a><a class=\"vf-btn vf-btn--pri\" href=\"#solicitar\" data-vf-model=\"PRV55 valve\">Request a quote<\/a><\/p><\/div><\/div><\/div><\/div><\/div><div class=\"wp-block-group vf-c2-group vfd-group--grandes is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-ghead is-layout-flow wp-block-group-is-layout-flow\"><h3 class=\"wp-block-heading\">Medium and large lines: up to DN150<\/h3><p class=\"wp-block-paragraph\">Carbon steel or CF3M stainless body, with EN or ANSI flanges; bronze, duplex, or super duplex on request.<\/p><\/div><div class=\"wp-block-group vf-c2-cards vf-t-ul is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-c2-card vfd-vf-item--p vfd-fl--vapor%20liq%20gas vfd-pmin--0.5 vfd-pmax--20 vfd-dnmin--15 vfd-dnmax--150 vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-img is-layout-flow wp-block-group-is-layout-flow\"><figure class=\"wp-block-image vf-img-suelta\"><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=\"Valfonta S3 pressure relief valve with spring loading and flanged connection\" class=\"wp-image-10230\" width=\"160\" height=\"160\" loading=\"lazy\"><\/a><\/figure><\/div><div class=\"wp-block-group vf-body is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-tag wp-block-paragraph\">Spring \u00b7 direct-acting<\/p><h3 class=\"wp-block-heading\"><a href=\"\/en\/product\/pressure-relief-valve-s3\/\">S3<\/a><\/h3><p class=\"vf-sub wp-block-paragraph\">Direct-acting relief valve with guided plug and Class IV or VI seat leakage. Approved for fire protection.<\/p><div class=\"wp-block-group vf-t-dl is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Set pressure<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">0.5 to 20 barg<\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Size<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">DN15 to DN150 <small>DN125\u2013150 on request<\/small><\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Temperature<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">up to 220 \u00b0C<\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Steam<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">Yes<\/p><\/div><\/div><p class=\"vf-fit wp-block-paragraph\"><b>Choose it if<\/b> you need a direct-acting valve, with no diaphragm or control line, up to 20 barg; for example, in a pump bypass.<\/p><div class=\"wp-block-group vf-act is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a class=\"vf-btn vf-btn--sec\" href=\"\/en\/product\/pressure-relief-valve-s3\/\">View product<\/a><a class=\"vf-btn vf-btn--pri\" href=\"#solicitar\" data-vf-model=\"S3 valve\">Request a quote<\/a><\/p><\/div><\/div><\/div><div class=\"wp-block-group vf-c2-card vfd-vf-item--p vfd-fl--vapor%20liq%20gas vfd-pmin--0.5 vfd-pmax--15 vfd-dnmin--15 vfd-dnmax--150 vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-img is-layout-flow wp-block-group-is-layout-flow\"><figure class=\"wp-block-image vf-img-suelta\"><a href=\"\/en\/product\/pressure-excess-valve-s1\/\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/ok-M1-S1-3D-700x700-1.jpg\" alt=\"Valfonta S1 excess pressure valve with diaphragm actuator and flanged connection\" class=\"wp-image-192\" width=\"160\" height=\"160\" loading=\"lazy\"><\/a><\/figure><\/div><div class=\"wp-block-group vf-body is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-tag wp-block-paragraph\">Diaphragm and bellows<\/p><h3 class=\"wp-block-heading\"><a href=\"\/en\/product\/pressure-excess-valve-s1\/\">S1<\/a><\/h3><p class=\"vf-sub wp-block-paragraph\">Globe-type excess pressure valve with diaphragm, up to DN150 and Kv 240 m\u00b3\/h.<\/p><div class=\"wp-block-group vf-t-dl is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Set pressure<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">0.5 to 15 barg<\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Size<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">DN15 to DN150<\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Temperature<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">up to 220 \u00b0C<\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Steam<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">Yes <small>with condensate pot<\/small><\/p><\/div><\/div><p class=\"vf-fit wp-block-paragraph\"><b>Choose it if<\/b> you need high flow rates, up to DN150, or steam up to 220 \u00b0C.<\/p><div class=\"wp-block-group vf-act is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a class=\"vf-btn vf-btn--sec\" href=\"\/en\/product\/pressure-excess-valve-s1\/\">View product<\/a><a class=\"vf-btn vf-btn--pri\" href=\"#solicitar\" data-vf-model=\"S1 valve\">Request a quote<\/a><\/p><\/div><\/div><\/div><div class=\"wp-block-group vf-c2-card vfd-vf-item--p vfd-fl--vapor%20liq%20gas vfd-pmin--0.02 vfd-pmax--10 vfd-dnmin--15 vfd-dnmax--100 vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-img is-layout-flow wp-block-group-is-layout-flow\"><figure class=\"wp-block-image vf-img-suelta\"><a href=\"\/en\/product\/pressure-excess-valve-s2\/\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/ok-M2-PROVISIONAL-700x700-1.jpg\" alt=\"Valfonta S2 excess pressure valve with diaphragm actuator and flanged connection\" class=\"wp-image-193\" width=\"160\" height=\"160\" loading=\"lazy\"><\/a><\/figure><\/div><div class=\"wp-block-group vf-body is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-tag wp-block-paragraph\">Diaphragm \u00b7 internal sensing<\/p><h3 class=\"wp-block-heading\"><a href=\"\/en\/product\/pressure-excess-valve-s2\/\">S2<\/a><\/h3><p class=\"vf-sub wp-block-paragraph\">Diaphragm excess pressure valve with plunger-balanced seat.<\/p><div class=\"wp-block-group vf-t-dl is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Set pressure<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">0.02 to 10 barg<\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Size<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">DN15 to DN100<\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Temperature<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">up to 180 \u00b0C<\/p><\/div><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-t-dt vf-p0 wp-block-paragraph\">Steam<\/p><p class=\"vf-t-dd vf-p0 wp-block-paragraph\">At low temperature <small>with external sensing<\/small><\/p><\/div><\/div><p class=\"vf-fit wp-block-paragraph\"><b>Choose it if<\/b> you need low set pressures, from 0.02 barg, with gases, compressed air, or liquids, without a control line.<\/p><div class=\"wp-block-group vf-act is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a class=\"vf-btn vf-btn--sec\" href=\"\/en\/product\/pressure-excess-valve-s2\/\">View product<\/a><a class=\"vf-btn vf-btn--pri\" href=\"#solicitar\" data-vf-model=\"S2 valve\">Request a quote<\/a><\/p><\/div><\/div><\/div><\/div><\/div><\/div><div class=\"wp-block-group vf-c2-table vfa-hidden-- is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-tbl-wrap is-layout-flow wp-block-group-is-layout-flow\"><figure class=\"wp-block-table vf-tbl vf-tbl--grid\"><table><thead><tr><th scope=\"col\"><button type=\"button\" data-vf-sort=\"0\" data-type=\"t\">Model<\/button><\/th><th scope=\"col\"><button type=\"button\" data-vf-sort=\"1\" data-type=\"t\">Construction<\/button><\/th><th scope=\"col\"><button type=\"button\" data-vf-sort=\"2\" data-type=\"n\">DN<\/button><\/th><th scope=\"col\"><button type=\"button\" data-vf-sort=\"3\" data-type=\"n\">Set pressure (barg)<\/button><\/th><th scope=\"col\"><button type=\"button\" data-vf-sort=\"4\" data-type=\"n\">Max. T (\u00b0C)<\/button><\/th><th scope=\"col\"><button type=\"button\" data-vf-sort=\"5\" data-type=\"n\">Steam<\/button><\/th><\/tr><\/thead><tbody><tr><th scope=\"row\"><span class=\"vf-dato vf-dato-fila\" hidden data-vf-item=\"t\" data-fl=\"liq gas\" data-pmin=\"0.5\" data-pmax=\"10\" data-dnmin=\"15\" data-dnmax=\"25\"><\/span><span class=\"vf-dato\" hidden data-s=\"PRV53\"><\/span><a href=\"\/en\/product\/pressure-excess-valve-prv53\/\">PRV53<\/a><\/th><td><span class=\"vf-dato\" hidden data-s=\"Piston\"><\/span>Piston<\/td><td><span class=\"vf-dato\" hidden data-s=\"15\"><\/span>15 \u2013 25<\/td><td><span class=\"vf-dato\" hidden data-s=\"0.5\"><\/span>0,5 \u2013 10<\/td><td><span class=\"vf-dato\" hidden data-s=\"150\"><\/span>150<\/td><td><span class=\"vf-dato\" hidden data-s=\"0\"><\/span>No<\/td><\/tr><tr><th scope=\"row\"><span class=\"vf-dato vf-dato-fila\" hidden data-vf-item=\"t\" data-fl=\"vapor liq gas\" data-pmin=\"0.5\" data-pmax=\"12\" data-dnmin=\"15\" data-dnmax=\"25\"><\/span><span class=\"vf-dato\" hidden data-s=\"PRV54\"><\/span><a href=\"\/en\/product\/pressure-excess-valve-prv54\/\">PRV54<\/a><\/th><td><span class=\"vf-dato\" hidden data-s=\"Bellows\"><\/span>Bellows<\/td><td><span class=\"vf-dato\" hidden data-s=\"15\"><\/span>15 \u2013 25<\/td><td><span class=\"vf-dato\" hidden data-s=\"0.5\"><\/span>0,5 \u2013 12<\/td><td><span class=\"vf-dato\" hidden data-s=\"210\"><\/span>210<\/td><td><span class=\"vf-dato\" hidden data-s=\"1\"><\/span>Yes<\/td><\/tr><tr><th scope=\"row\"><span class=\"vf-dato vf-dato-fila\" hidden data-vf-item=\"t\" data-fl=\"vapor liq gas\" data-pmin=\"0.01\" data-pmax=\"8\" data-dnmin=\"15\" data-dnmax=\"25\"><\/span><span class=\"vf-dato\" hidden data-s=\"PRV55\"><\/span><a href=\"\/en\/product\/excess-pressure-valve-model-prv55\/\">PRV55<\/a><\/th><td><span class=\"vf-dato\" hidden data-s=\"Diaphragm\"><\/span>Diaphragm<\/td><td><span class=\"vf-dato\" hidden data-s=\"15\"><\/span>15 \u2013 25<\/td><td><span class=\"vf-dato\" hidden data-s=\"0.01\"><\/span>0,01 \u2013 8<\/td><td><span class=\"vf-dato\" hidden data-s=\"150\"><\/span>150<\/td><td><span class=\"vf-dato\" hidden data-s=\"1\"><\/span>Yes<\/td><\/tr><tr><th scope=\"row\"><span class=\"vf-dato vf-dato-fila\" hidden data-vf-item=\"t\" data-fl=\"vapor liq gas\" data-pmin=\"0.5\" data-pmax=\"20\" data-dnmin=\"15\" data-dnmax=\"150\"><\/span><span class=\"vf-dato\" hidden data-s=\"S3\"><\/span><a href=\"\/en\/product\/pressure-relief-valve-s3\/\">S3<\/a><\/th><td><span class=\"vf-dato\" hidden data-s=\"Spring\"><\/span>Spring<\/td><td><span class=\"vf-dato\" hidden data-s=\"15\"><\/span>15 \u2013 150<\/td><td><span class=\"vf-dato\" hidden data-s=\"0.5\"><\/span>0,5 \u2013 20<\/td><td><span class=\"vf-dato\" hidden data-s=\"220\"><\/span>220<\/td><td><span class=\"vf-dato\" hidden data-s=\"1\"><\/span>Yes<\/td><\/tr><tr><th scope=\"row\"><span class=\"vf-dato vf-dato-fila\" hidden data-vf-item=\"t\" data-fl=\"vapor liq gas\" data-pmin=\"0.5\" data-pmax=\"15\" data-dnmin=\"15\" data-dnmax=\"150\"><\/span><span class=\"vf-dato\" hidden data-s=\"S1\"><\/span><a href=\"\/en\/product\/pressure-excess-valve-s1\/\">S1<\/a><\/th><td><span class=\"vf-dato\" hidden data-s=\"Diaphragm and bellows\"><\/span>Diaphragm and bellows<\/td><td><span class=\"vf-dato\" hidden data-s=\"15\"><\/span>15 \u2013 150<\/td><td><span class=\"vf-dato\" hidden data-s=\"0.5\"><\/span>0,5 \u2013 15<\/td><td><span class=\"vf-dato\" hidden data-s=\"220\"><\/span>220<\/td><td><span class=\"vf-dato\" hidden data-s=\"1\"><\/span>Yes<\/td><\/tr><tr><th scope=\"row\"><span class=\"vf-dato vf-dato-fila\" hidden data-vf-item=\"t\" data-fl=\"vapor liq gas\" data-pmin=\"0.02\" data-pmax=\"10\" data-dnmin=\"15\" data-dnmax=\"100\"><\/span><span class=\"vf-dato\" hidden data-s=\"S2\"><\/span><a href=\"\/en\/product\/pressure-excess-valve-s2\/\">S2<\/a><\/th><td><span class=\"vf-dato\" hidden data-s=\"Diaphragm\"><\/span>Diaphragm<\/td><td><span class=\"vf-dato\" hidden data-s=\"15\"><\/span>15 \u2013 100<\/td><td><span class=\"vf-dato\" hidden data-s=\"0.02\"><\/span>0,02 \u2013 10<\/td><td><span class=\"vf-dato\" hidden data-s=\"180\"><\/span>180<\/td><td><span class=\"vf-dato\" hidden data-s=\"1\"><\/span>Yes<\/td><\/tr><tr><th scope=\"row\"><span class=\"vf-dato vf-dato-fila\" hidden data-vf-item=\"t\" data-fl=\"vapor liq gas\" data-pmin=\"0.5\" data-pmax=\"20\" data-dnmin=\"15\" data-dnmax=\"100\"><\/span><span class=\"vf-dato\" hidden data-s=\"S4\"><\/span>S4*<\/th><td><span class=\"vf-dato\" hidden data-s=\"Piston\"><\/span>Piston<\/td><td><span class=\"vf-dato\" hidden data-s=\"15\"><\/span>15 \u2013 100<\/td><td><span class=\"vf-dato\" hidden data-s=\"0.5\"><\/span>0,5 \u2013 20<\/td><td><span class=\"vf-dato\" hidden data-s=\"220\"><\/span>220<\/td><td><span class=\"vf-dato\" hidden data-s=\"1\"><\/span>Yes<\/td><\/tr><\/tbody><\/table><\/figure><\/div><p class=\"vf-note wp-block-paragraph\">Data from the Valfonta excess pressure summary catalog (2025); S2 set pressure from its datasheet. All accept water, oil, air, and non-flammable gases. * The S4 has no datasheet on the website: contact us. S3: DN125 and DN150 on request. PRV53: up to 15 barg on request.<\/p><\/div><div class=\"wp-block-group vf-c2-empty vfa-hidden-- is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\"><b>No standard model matches these filters.<\/b> Valfonta adapts models and designs custom valves: tell us about your application in the <a href=\"#solicitar\" data-vf-model=\"I don&#x27;t know \/ I need advice\">form<\/a> or see the <a href=\"\/en\/control-valve-design\/\">custom design service<\/a>.<\/p><\/div><\/section><section id=\"como-funciona\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">How it works and where it is installed<\/h2><div class=\"wp-block-group vf-c2-how is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-txt is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">A pressure relief valve stays closed while the inlet pressure is below the set pressure. When the set pressure is exceeded, the valve opens gradually, in proportion to the pressure rise, discharges the excess flow, and closes again when the pressure returns to normal. This keeps the upstream pressure stable.<\/p><p class=\"wp-block-paragraph\">All of them are <strong>self-operated<\/strong>: an adjusting spring opposes the inlet pressure, with no air, electricity, or control system. The set pressure is fixed by the spring compression; the S1, S2, and S3 are delivered set to the requested value.<\/p><p class=\"wp-block-paragraph\">The typical installation is on a branch line, for example in a pump bypass, returning to the suction or the tank, with a strainer ahead of the valve and a pressure gauge upstream. See how to check the set pressure and <a href=\"\/en\/blog\/chattering-in-pressure-relief-valves\/\">why a relief valve chatters<\/a>.<\/p><\/div><div class=\"wp-block-group vf-diagram vf-t-figure is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-svgw is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><svg viewbox=\"0 0 900 240\" role=\"img\" aria-label=\"Installation diagram of a pressure relief or excess pressure valve on a branch line\"><path d=\"M20 90 H880\" stroke=\"#9aa0a6\" stroke-width=\"6\" fill=\"none\"><\/path><path d=\"M865 90 l14 0 -10 -7 m10 7 -10 7\" stroke=\"#1e2123\" stroke-width=\"3\" fill=\"none\"><\/path><rect x=\"60\" y=\"62\" width=\"90\" height=\"56\" rx=\"4\" fill=\"#fff\" stroke=\"#1e2123\" stroke-width=\"2\"><\/rect><circle cx=\"105\" cy=\"90\" r=\"16\" fill=\"none\" stroke=\"#1e2123\" stroke-width=\"2\"><\/circle><path d=\"M97 90 l18 0\" stroke=\"#1e2123\" stroke-width=\"2\"><\/path><path d=\"M420 90 V150\" stroke=\"#9aa0a6\" stroke-width=\"5\"><\/path><rect x=\"385\" y=\"150\" width=\"70\" height=\"46\" rx=\"4\" fill=\"#fdecf1\" stroke=\"#e6305d\" stroke-width=\"2\"><\/rect><path d=\"M420 160 v24 m-7 -8 7 8 7 -8\" stroke=\"#e6305d\" stroke-width=\"2.5\" fill=\"none\"><\/path><path d=\"M455 173 H640 V215\" stroke=\"#9aa0a6\" stroke-width=\"5\" fill=\"none\"><\/path><path d=\"M632 205 l8 12 8 -12\" stroke=\"#1e2123\" stroke-width=\"2.5\" fill=\"none\"><\/path><g><circle cx=\"300\" cy=\"51\" r=\"13\" fill=\"#fff\" stroke=\"#1e2123\" stroke-width=\"2\"><\/circle><line x1=\"300\" y1=\"64\" x2=\"300\" y2=\"90\" stroke=\"#1e2123\" stroke-width=\"2\"><\/line><line x1=\"300\" y1=\"51\" x2=\"307\" y2=\"44\" stroke=\"#e6305d\" stroke-width=\"2\"><\/line><\/g><rect x=\"720\" y=\"65\" width=\"110\" height=\"50\" rx=\"4\" fill=\"#fff\" stroke=\"#1e2123\" stroke-width=\"2\"><\/rect><circle cx=\"105\" cy=\"138\" r=\"11\" fill=\"#1e2123\"><\/circle><text x=\"105\" y=\"142\" font-size=\"12\" font-weight=\"700\" fill=\"#fff\" text-anchor=\"middle\" font-family=\"Montserrat,Arial\">1<\/text><circle cx=\"324\" cy=\"38\" r=\"11\" fill=\"#1e2123\"><\/circle><text x=\"324\" y=\"42\" font-size=\"12\" font-weight=\"700\" fill=\"#fff\" text-anchor=\"middle\" font-family=\"Montserrat,Arial\">2<\/text><circle cx=\"420\" cy=\"218\" r=\"11\" fill=\"#e6305d\"><\/circle><text x=\"420\" y=\"222\" font-size=\"12\" font-weight=\"700\" fill=\"#fff\" text-anchor=\"middle\" font-family=\"Montserrat,Arial\">3<\/text><circle cx=\"640\" cy=\"232\" r=\"11\" fill=\"#1e2123\"><\/circle><text x=\"640\" y=\"236\" font-size=\"12\" font-weight=\"700\" fill=\"#fff\" text-anchor=\"middle\" font-family=\"Montserrat,Arial\">4<\/text><circle cx=\"775\" cy=\"136\" r=\"11\" fill=\"#1e2123\"><\/circle><text x=\"775\" y=\"140\" font-size=\"12\" font-weight=\"700\" fill=\"#fff\" text-anchor=\"middle\" font-family=\"Montserrat,Arial\">5<\/text><\/svg><\/p><\/div><div class=\"wp-block-group vf-t-figcaption is-layout-flow wp-block-group-is-layout-flow\"><ol class=\"wp-block-list\"><li>Pump or equipment that generates the pressure<\/li><li>Upstream pressure gauge<\/li><li>Pressure relief valve<\/li><li>Return to the suction side or to the tank<\/li><li>Main line to the point of use<\/li><\/ol><\/div><\/div><\/div><\/section><section id=\"diferencias\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">Relief, safety, or reducing: which one you need<\/h2><div class=\"wp-block-group vf-tbl-wrap is-layout-flow wp-block-group-is-layout-flow\"><figure class=\"wp-block-table vf-tbl vf-c2-cmp\"><table><thead><tr><th><\/th><th>Relief or excess pressure valve<\/th><th>Safety valve<\/th><th>Reducing valve<\/th><\/tr><\/thead><tbody><tr><th scope=\"row\">What it does<\/th><td>Holds the <strong>upstream<\/strong> pressure at the set pressure.<\/td><td>Protects tanks, boilers, or pipes against overpressure.<\/td><td>Holds the <strong>downstream<\/strong> pressure at the set value.<\/td><\/tr><tr><th scope=\"row\">How it opens<\/th><td>In proportion to the pressure rise; closes when the pressure returns to normal.<\/td><td>When the popping pressure is reached; ALPER and JAS valves open fully and instantly.<\/td><td>Closes when the outlet pressure rises and opens when it drops.<\/td><\/tr><tr><th scope=\"row\">Accessory type<\/th><td>Pressure accessory<\/td><td>Safety accessory<\/td><td>Pressure accessory<\/td><\/tr><tr><th scope=\"row\">Where it goes<\/th><td>On a branch line, for example in a pump bypass.<\/td><td>On the equipment or line it protects.<\/td><td>In the line, upstream of the point of use.<\/td><\/tr><tr><th scope=\"row\">Models<\/th><td>S3, S1, S2, PRV53, PRV54, and PRV55<\/td><td><a href=\"\/en\/safety-valves\/\">Safety valves<\/a><\/td><td><a href=\"\/en\/pressure-reducing-valves\/\">Pressure reducing valves<\/a><\/td><\/tr><\/tbody><\/table><\/figure><\/div><p class=\"wp-block-paragraph\"><strong>A relief valve does not replace a safety valve.<\/strong> If the installation needs overpressure protection, both must be installed. We explain it in <a href=\"\/en\/blog\/what-difference-between-safety-valve-and-relief-valve\/\">the difference between a safety valve and a relief valve<\/a>.<\/p><\/section><section id=\"aplicaciones\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">Applications<\/h2><ul class=\"vf-pdp-apps wp-block-list\"><li><b>Pump bypass<\/b><span>Return the excess flow to the suction or the tank with the <a href=\"\/en\/product\/pressure-relief-valve-s3\/\">S3<\/a> or the <a href=\"\/en\/product\/pressure-excess-valve-prv53\/\">PRV53<\/a>.<\/span><\/li><li><b>Fire protection<\/b><span>The <a href=\"\/en\/product\/pressure-relief-valve-s3\/\">S3<\/a> has a specific approval for these installations; ask us for the certificate with your quote.<\/span><\/li><li><b>Steam networks<\/b><span>Steam networks and heat exchangers, with the <a href=\"\/en\/product\/pressure-excess-valve-s1\/\">S1<\/a>, the <a href=\"\/en\/product\/pressure-excess-valve-prv54\/\">PRV54<\/a>, or the <a href=\"\/en\/product\/excess-pressure-valve-model-prv55\/\">PRV55<\/a>.<\/span><\/li><li><b>Gases and compressed air<\/b><span>Set pressures from 10 mbar with the <a href=\"\/en\/product\/excess-pressure-valve-model-prv55\/\">PRV55<\/a> or from 0.02 barg with the <a href=\"\/en\/product\/pressure-excess-valve-s2\/\">S2<\/a>.<\/span><\/li><li><b>Supply between zones<\/b><span>With the <a href=\"\/en\/product\/pressure-excess-valve-s2\/\">S2<\/a>, a zone with excess pressure feeds another lower-pressure zone without starving the main line.<\/span><\/li><li><b>Laboratories and sanitary plants<\/b><span>Small 316L stainless steel circuits with the <a href=\"\/en\/product\/pressure-excess-valve-prv53\/\">PRV53<\/a>, the <a href=\"\/en\/product\/pressure-excess-valve-prv54\/\">PRV54<\/a>, or the <a href=\"\/en\/product\/excess-pressure-valve-model-prv55\/\">PRV55<\/a>.<\/span><\/li><\/ul><\/section><section id=\"normativa\" class=\"wp-block-group vf-c2-norm is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">Standards and certificates<\/h2><div class=\"wp-block-group vf-norm 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\"><p class=\"vf-envolt wp-block-paragraph\"><b>PED 2014\/68\/EU<\/b><\/p><p class=\"wp-block-paragraph\">PRV53, PRV54, and PRV55: Article 4.3, no CE marking. S1, S2, and S3: the nameplate indicates whether the valve requires CE marking.<\/p><\/div><div class=\"wp-block-group vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><b>ATEX II 2 GD<\/b><\/p><p class=\"wp-block-paragraph\">S1, S2, PRV53, PRV54, and PRV55 (certificate LOM 14.034 U), for zones 1, 2, 21, and 22. For the S3, contact us.<\/p><\/div><div class=\"wp-block-group vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><b>ISO 9001:2015<\/b><\/p><p class=\"wp-block-paragraph\">Design, manufacture, and sale of globe control valves for process control.<\/p><\/div><\/div><p class=\"wp-block-paragraph\">Download <a href=\"\/en\/certificates\/\">Valfonta\u2019s certificates<\/a>.<\/p><\/section><section id=\"preguntas\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">Frequently asked questions about pressure relief valves<\/h2><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>What is the difference between a relief valve and a safety valve?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">A relief valve opens in proportion to the pressure rise and modulates to hold the pressure at the set pressure: it is a pressure accessory, not a safety accessory. A safety valve protects tanks, boilers, or pipes against overpressure. If you need protection, also install one of our <a href=\"\/en\/safety-valves\/\">safety valves<\/a>.<\/p><\/div><\/details><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Are a relief valve and an excess pressure valve the same thing?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">Yes, they perform the same function. The Valfonta catalog groups them as excess pressure valves; in our range, the S3 is the one called a relief valve.<\/p><\/div><\/details><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Which relief valve do I need for steam?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">The S3 and S1 operate up to 220 \u00b0C, the PRV54 up to 210 \u00b0C, and the PRV55 up to 150 \u00b0C; the S2 accepts low-temperature steam with external sensing and a condensate pot. The PRV53 is not suitable for steam.<\/p><\/div><\/details><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>What set pressure can be adjusted?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">From 0.01 barg (10 mbar) with the PRV55 and 0.02 barg with the S2, up to 20 barg with the S3. The S1, S2, and S3 are delivered preset to the requested value.<\/p><\/div><\/details><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Where is a relief valve installed?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">Normally on a branch of the main line, for example in a pump bypass, returning to the suction or the tank, with a strainer ahead of the valve and a pressure gauge upstream to check the set pressure.<\/p><\/div><\/details><\/section><section id=\"guias\" class=\"wp-block-group vf-c2-more 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\">Technical guides on relief valves<\/h2><div class=\"wp-block-group vf-arts 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\"><p class=\"vf-envolt wp-block-paragraph\"><a href=\"\/en\/blog\/pressure-relief-valve-how-to-choose-it\/\">Relief valve: how to choose the right one<\/a><\/p><\/div><div class=\"wp-block-group vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a href=\"\/en\/blog\/what-difference-between-safety-valve-and-relief-valve\/\">Difference between a safety valve and a relief valve<\/a><\/p><\/div><div class=\"wp-block-group vf-sin-idioma vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a data-vf-href=\"\/blog\/tarado-de-valvulas-de-alivio\/\">Relief valve set pressure safety audit<\/a><\/p><\/div><div class=\"wp-block-group vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a href=\"\/en\/blog\/chattering-in-pressure-relief-valves\/\">Relief valve chattering: what is it?<\/a><\/p><\/div><div class=\"wp-block-group vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a href=\"\/en\/blog\/water-pressure-relief-valve\/\">Relief valve for water, steam, and gases<\/a><\/p><\/div><div class=\"wp-block-group vf-t-li is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><a href=\"\/en\/blog\/fire-protection-pressure-relief-valves\/\">Pressure relief valves for fire protection<\/a><\/p><\/div><\/div><\/div><p class=\"vf-fams wp-block-paragraph\"><b>Other families:<\/b> <a href=\"\/en\/safety-valves\/\">Safety valves<\/a> \u00b7 <a href=\"\/en\/pressure-reducing-valves\/\">Pressure reducing valves<\/a> \u00b7 <a href=\"\/en\/control-valve\/\">Control valves<\/a> \u00b7 <a href=\"\/en\/control-valve-design\/\">Custom design<\/a><\/p><\/section><section id=\"solicitar\" 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\">Request a quote for a pressure relief valve<\/h2><p class=\"wp-block-paragraph\">Give us your installation details and we will recommend the right model, size, spring range, and gaskets for your set pressure.<\/p><ul class=\"wp-block-list\"><li>Fluid and operating temperature<\/li><li>Set pressure and normal operating pressure<\/li><li>Flow rate the valve must discharge<\/li><li>Connection type (threaded or flanged) and body material<\/li><\/ul><p class=\"vf-pdp-contact wp-block-paragraph\">You can also call <a href=\"tel:+34933720888\">933 720 888<\/a>.<\/p><\/div>\n<div class=\"wpcf7 no-js\" id=\"wpcf7-f541-o1\" lang=\"en-US\" dir=\"ltr\" data-wpcf7-id=\"541\">\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\/pages\/624#wpcf7-f541-o1\" method=\"post\" class=\"wpcf7-form init vf-form wpcf7-acceptance-as-validation\" aria-label=\"Contact form\" novalidate=\"novalidate\" data-status=\"init\" toolname=\"solicitar_oferta\" tooldescription=\"Request a quote from Valfonta for the models on this page (model, size, fluid and pressures); a member of the team will reply.\">\n<fieldset class=\"hidden-fields-container\"><input type=\"hidden\" name=\"_wpcf7\" value=\"541\" \/><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-f541-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=\"1792698947.3248fbd6be5c7d77\" \/>\n<\/fieldset>\n<input class=\"wpcf7-form-control wpcf7-hidden\" value=\"V\u00e1lvulas de alivio de presi\u00f3n\" type=\"hidden\" name=\"familia\" \/><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\" \/><\/span><\/label><label>Email *<span class=\"wpcf7-form-control-wrap\" data-name=\"email\"><input size=\"40\" maxlength=\"400\" class=\"wpcf7-form-control wpcf7-email wpcf7-validates-as-required wpcf7-text wpcf7-validates-as-email\" autocomplete=\"email\" aria-required=\"true\" aria-invalid=\"false\" value=\"\" type=\"email\" name=\"email\" \/><\/span><\/label><label>Phone<span class=\"wpcf7-form-control-wrap\" data-name=\"telefono\"><input size=\"40\" maxlength=\"400\" class=\"wpcf7-form-control wpcf7-tel wpcf7-text wpcf7-validates-as-tel\" autocomplete=\"tel\" aria-invalid=\"false\" value=\"\" type=\"tel\" name=\"telefono\" \/><\/span><\/label><label class=\"vf-full\">Model<span class=\"wpcf7-form-control-wrap\" data-name=\"modelo\"><select class=\"wpcf7-form-control wpcf7-select\" aria-invalid=\"false\" name=\"modelo\"><option value=\"\">Select<\/option><option value=\"PRV53 valve\">PRV53 valve<\/option><option value=\"PRV54 valve\">PRV54 valve<\/option><option value=\"PRV55 valve\">PRV55 valve<\/option><option value=\"S3 valve\">S3 valve<\/option><option value=\"S1 valve\">S1 valve<\/option><option value=\"S2 valve\">S2 valve<\/option><option value=\"I don&#039;t know \/ I need advice\">I don&#039;t know \/ I need advice<\/option><\/select><\/span><\/label><label>Fluid<span class=\"wpcf7-form-control-wrap\" data-name=\"fluido\"><input size=\"40\" maxlength=\"400\" class=\"wpcf7-form-control wpcf7-text\" aria-invalid=\"false\" placeholder=\"steam, water, air\u2026\" value=\"\" type=\"text\" name=\"fluido\" \/><\/span><\/label><label>Set pressure (barg)<span class=\"wpcf7-form-control-wrap\" data-name=\"tarado\"><input size=\"40\" maxlength=\"400\" class=\"wpcf7-form-control wpcf7-text\" aria-invalid=\"false\" value=\"\" type=\"text\" name=\"tarado\" \/><\/span><\/label><label>Flow rate to discharge<span class=\"wpcf7-form-control-wrap\" data-name=\"caudal\"><input size=\"40\" maxlength=\"400\" class=\"wpcf7-form-control wpcf7-text\" aria-invalid=\"false\" placeholder=\"e.g. 5 m\u00b3\/h, or kg\/h of steam\" value=\"\" type=\"text\" name=\"caudal\" \/><\/span><\/label><label>Temperature (\u00b0C)<span class=\"wpcf7-form-control-wrap\" data-name=\"temperatura\"><input size=\"40\" maxlength=\"400\" class=\"wpcf7-form-control wpcf7-text\" aria-invalid=\"false\" value=\"\" type=\"text\" name=\"temperatura\" \/><\/span><\/label><label class=\"vf-full\">Message<span class=\"wpcf7-form-control-wrap\" data-name=\"mensaje\"><textarea cols=\"40\" rows=\"4\" maxlength=\"2000\" class=\"wpcf7-form-control wpcf7-textarea\" aria-invalid=\"false\" 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 request\" \/><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=\"#solicitar\">Request a quote<\/a><\/p><\/div><\/article><\/div><\/div>","protected":false},"excerpt":{"rendered":"<p>Home\u203aPressure relief valves Designed and manufactured in Badalona since 1962 Pressure relief valves They hold upstream pressure at the set pressure: when it is exceeded, they open in proportion to the rise and discharge the excess, with no auxiliary power. They are also called excess pressure valves. Six spring, piston, diaphragm, or bellows models for ... <a title=\"Pressure relief valves\" class=\"read-more\" href=\"https:\/\/www.valfonta.com\/en\/pressure-relief-valve\/\" aria-label=\"Read more about Pressure relief valves\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"_generate-full-width-content":"true","_generate-disable-headline":"true","rank_math_title":"Pressure relief valves: 6 models | Valfonta","rank_math_description":"Valfonta pressure relief (excess pressure) valves: 6 models, DN15 to DN150, set pressures 0.01 to 20 barg, up to 220 \u00b0C. Choose and request a quote.","rank_math_focus_keyword":"","vf_jsonld":"[{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Organization\",\"@id\":\"https:\/\/www.valfonta.com\/#organization\",\"name\":\"Valfonta\",\"legalName\":\"Val Fonta, S.L.\",\"taxID\":\"B59935718\",\"url\":\"https:\/\/www.valfonta.com\/en\/\",\"logo\":{\"@type\":\"ImageObject\",\"url\":\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/valfonta-logo.webp\"},\"foundingDate\":\"1962\",\"email\":\"valfonta@valfonta.com\",\"telephone\":\"+34 933 720 888\",\"address\":{\"@type\":\"PostalAddress\",\"streetAddress\":\"C\/ Bronze 26, Pol. Ind. 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\":\"CollectionPage\",\"@id\":\"https:\/\/www.valfonta.com\/en\/pressure-relief-valve\/#webpage\",\"url\":\"https:\/\/www.valfonta.com\/en\/pressure-relief-valve\/\",\"name\":\"Pressure relief valves: 6 models | Valfonta\",\"description\":\"Valfonta pressure relief (excess pressure) valves: 6 models, DN15 to DN150, set pressures 0.01 to 20 barg, up to 220 \u00b0C. Choose and request a quote.\",\"isPartOf\":{\"@id\":\"https:\/\/www.valfonta.com\/#website\"},\"about\":{\"@id\":\"https:\/\/www.valfonta.com\/#organization\"},\"inLanguage\":\"en\",\"datePublished\":\"2020-03-11T10:17:12+02:00\",\"dateModified\":\"2026-01-14T01:27:36+02:00\",\"breadcrumb\":{\"@id\":\"https:\/\/www.valfonta.com\/en\/pressure-relief-valve\/#breadcrumb\"},\"mainEntity\":{\"@id\":\"https:\/\/www.valfonta.com\/en\/pressure-relief-valve\/#modelos\"},\"primaryImageOfPage\":{\"@type\":\"ImageObject\",\"url\":\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/ok-S3-2017.jpg\"}},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.valfonta.com\/en\/pressure-relief-valve\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.valfonta.com\/en\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Pressure relief valves\",\"item\":\"https:\/\/www.valfonta.com\/en\/pressure-relief-valve\/\"}]},{\"@type\":\"ItemList\",\"@id\":\"https:\/\/www.valfonta.com\/en\/pressure-relief-valve\/#modelos\",\"name\":\"Pressure relief valves\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"url\":\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-prv53\/\",\"name\":\"PRV53 excess pressure valve\"},{\"@type\":\"ListItem\",\"position\":2,\"url\":\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-prv54\/\",\"name\":\"PRV54 excess pressure valve\"},{\"@type\":\"ListItem\",\"position\":3,\"url\":\"https:\/\/www.valfonta.com\/en\/product\/excess-pressure-valve-model-prv55\/\",\"name\":\"PRV55 excess pressure valve\"},{\"@type\":\"ListItem\",\"position\":4,\"url\":\"https:\/\/www.valfonta.com\/en\/product\/pressure-relief-valve-s3\/\",\"name\":\"S3 pressure relief valve\"},{\"@type\":\"ListItem\",\"position\":5,\"url\":\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s1\/\",\"name\":\"S1 excess pressure valve\"},{\"@type\":\"ListItem\",\"position\":6,\"url\":\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s2\/\",\"name\":\"S2 excess pressure valve\"}]},{\"@type\":\"FAQPage\",\"@id\":\"https:\/\/www.valfonta.com\/en\/pressure-relief-valve\/#faq\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"What is the difference between a relief valve and a safety valve?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"A relief valve opens in proportion to the pressure rise and modulates to hold the pressure at the set pressure: it is a pressure accessory, not a safety accessory. A safety valve protects tanks, boilers, or pipes against overpressure. If you need protection, also install one of our safety valves.\"}},{\"@type\":\"Question\",\"name\":\"Are a relief valve and an excess pressure valve the same thing?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes, they perform the same function. The Valfonta catalog groups them as excess pressure valves; in our range, the S3 is the one called a relief valve.\"}},{\"@type\":\"Question\",\"name\":\"Which relief valve do I need for steam?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"The S3 and S1 operate up to 220 \u00b0C, the PRV54 up to 210 \u00b0C, and the PRV55 up to 150 \u00b0C; the S2 accepts low-temperature steam with external sensing and a condensate pot. The PRV53 is not suitable for steam.\"}},{\"@type\":\"Question\",\"name\":\"What set pressure can be adjusted?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"From 0.01 barg (10 mbar) with the PRV55 and 0.02 barg with the S2, up to 20 barg with the S3. The S1, S2, and S3 are delivered preset to the requested value.\"}},{\"@type\":\"Question\",\"name\":\"Where is a relief valve installed?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Normally on a branch of the main line, for example in a pump bypass, returning to the suction or the tank, with a strainer ahead of the valve and a pressure gauge upstream to check the set pressure.\"}}]}]}]","footnotes":"","_vg_translation_of":"43","_vg_lang":"en","_vg_wpml_state":"{\"lang\":\"en\",\"trid\":\"43\",\"src\":\"es\"}"},"class_list":["post-624","page","type-page","status-publish"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/pages\/624","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/types\/page"}],"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=624"}],"version-history":[{"count":7,"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/pages\/624\/revisions"}],"predecessor-version":[{"id":10315,"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/pages\/624\/revisions\/10315"}],"wp:attachment":[{"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/media?parent=624"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}