{"id":653,"date":"2026-10-02T13:17:41","date_gmt":"2026-10-02T11:17:41","guid":{"rendered":"https:\/\/www.valfonta.com\/producto\/pressure-excess-valve-s1\/"},"modified":"2026-10-22T09:22:50","modified_gmt":"2026-10-22T07:22:50","slug":"pressure-excess-valve-s1","status":"publish","type":"product","link":"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s1\/","title":{"rendered":"S1 excess pressure valve"},"content":{"rendered":"<div class=\"wp-block-group vf-raiz vf-pl-ficha-producto 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\" aria-hidden=\"true\">\u203a<\/span><a href=\"https:\/\/www.valfonta.com\/en\/pressure-relief-valve\/\">Pressure relief valves<\/a><span class=\"vf-sep\" aria-hidden=\"true\">\u203a<\/span><span aria-current=\"page\">S1 excess pressure valve<\/span><\/p><\/nav><article class=\"wp-block-group vf-pdp vfd-model--S1 is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-pdp-hero is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-pdp-title is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-pdp-eyebrow wp-block-paragraph\">Excess pressure valve \u00b7 Diaphragm and bellows<\/p><h1 class=\"wp-block-heading\">S1 excess pressure valve<\/h1><\/div><div class=\"wp-block-group vf-pdp-media is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><span class=\"vf-pdp-badge\">Up to DN150<\/span><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=\"700\" height=\"700\" fetchpriority=\"high\"><\/p><\/div><div class=\"wp-block-group vf-pdp-body is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-lead wp-block-paragraph\">Self-operated, single-seat excess pressure valve with a diaphragm actuator and a stem sealed by a stainless steel bellows. It limits the inlet pressure to the set value, from 0.5 to 15 barg, on steam, compressed air, gases, and liquids, from DN15 to DN150.<\/p><ul class=\"vf-pdp-keys wp-block-list\"><li><span>Sizes<\/span><b>DN15 to DN150<\/b><\/li><li><span>Pressure rating<\/span><b>PN25 \u2013 PN40 <small>Class 150 \u2013 300<\/small><\/b><\/li><li><span>Set pressure range<\/span><b>0.5 to 15 barg<\/b><\/li><li><span>Temperature<\/span><b>up to 220 \u00b0C <small>depending on diaphragm<\/small><\/b><\/li><li><span>Kv<\/span><b>3.5 to 240 m\u00b3\/h<\/b><\/li><li><span>Fluids<\/span><b>Steam, liquids, air, and gases<\/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=\"\/wp-content\/uploads\/2026\/10\/S1-18A-ENG.pdf\" target=\"_blank\" rel=\"noopener\">Download datasheet <small>PDF<\/small><\/a><\/p><\/div><p class=\"vf-pdp-contact wp-block-paragraph\">Questions about set pressure or sizing? Call <a href=\"tel:+34933720888\">933 720 888<\/a> or email <a href=\"mailto:valfonta@valfonta.com\">valfonta@valfonta.com<\/a>.<\/p><\/div><\/div><ul class=\"vf-pdp-trust wp-block-list\"><li>In-house design and manufacturing in Badalona<\/li><li>ATEX II 2 GD marking for zones 1 and 21<\/li><li>Stem sealed by a double-layer stainless steel bellows<\/li><li>Genuine spare parts by serial number<\/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=\"#aplicaciones\">Applications<\/a><\/li><li><a href=\"#especificaciones\">Specifications<\/a><\/li><li><a href=\"#funcionamiento\">Operation<\/a><\/li><li><a href=\"#instalacion\">Installation<\/a><\/li><li><a href=\"#documentacion\">Documentation<\/a><\/li><li><a href=\"#comparar\">Compare<\/a><\/li><li><a href=\"#preguntas\">FAQ<\/a><\/li><li><a href=\"#solicitar\">Request a quote<\/a><\/li><\/ul><\/nav><section id=\"aplicaciones\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-pdp-two 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\">What the S1 is used for<\/h2><p class=\"wp-block-paragraph\">The <strong>S1<\/strong> is a self-operated <a href=\"https:\/\/www.valfonta.com\/en\/pressure-relief-valve\/\">excess pressure valve<\/a> that needs no auxiliary power. It stays closed while the inlet pressure is below the set value and opens proportionally when the pressure exceeds it, so the upstream pressure does not rise above the set value.<\/p><p class=\"wp-block-paragraph\">It goes up to DN150 and a Kv of 240 m\u00b3\/h. The valve stem is sealed by a <strong>double-layer stainless steel bellows<\/strong> with an anti-rotation system, and the diaphragm is fabric-reinforced. Learn more about <a href=\"https:\/\/www.valfonta.com\/en\/blog\/self-regulating-excess-pressure-valves\/\">self-regulating excess pressure valves<\/a>.<\/p><ul class=\"vf-pdp-apps wp-block-list\"><li><b>Steam<\/b><span>Up to 220 \u00b0C with EPDM+PTFE diaphragm and condensate pot.<\/span><\/li><li><b>Compressed air and inert gases<\/b><span>Limits line pressure to the set value.<\/span><\/li><li><b>Water, oil, and other liquids<\/b><span>Proportional relief of excess pressure.<\/span><\/li><li><b>Large-diameter lines<\/b><span>From DN15 to DN150, with Kv up to 240 m\u00b3\/h.<\/span><\/li><li><b>ATEX zones<\/b><span>Category II 2 GD for zones 1, 2, 21, and 22.<\/span><\/li><\/ul><\/div><aside class=\"wp-block-group vf-pdp-fit is-layout-flow wp-block-group-is-layout-flow\"><h3 class=\"wp-block-heading\">Choose the S1 if\u2026<\/h3><ul class=\"vf-si wp-block-list\"><li>You need up to DN150 or a Kv of up to 240 m\u00b3\/h.<\/li><li>You work with steam or hot liquids, up to 220 \u00b0C.<\/li><li>You want the stem sealed by a stainless steel bellows.<\/li><li>Your set pressure is between 0.5 and 15 barg.<\/li><\/ul><h3 class=\"wp-block-heading\">Choose another model if\u2026<\/h3><ul class=\"vf-no wp-block-list\"><li>You need a set pressure below 0.5 barg: the <a href=\"https:\/\/www.valfonta.com\/en\/product\/excess-pressure-valve-model-prv55\/\">PRV55<\/a> adjusts from 0.01 barg (DN15 to DN25).<\/li><li>Your set pressure is above 15 barg: the <a href=\"https:\/\/www.valfonta.com\/en\/product\/pressure-relief-valve-s3\/\">S3<\/a> goes up to 20 barg.<\/li><li>You prefer a valve with no diaphragm or control line: see the spring-loaded <a href=\"https:\/\/www.valfonta.com\/en\/product\/pressure-relief-valve-s3\/\">S3<\/a>.<\/li><li>You only need DN15 to DN25 in stainless steel: see the <a href=\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-prv53\/\">PRV53<\/a> or the <a href=\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-prv54\/\">PRV54<\/a> (steam up to 210 \u00b0C).<\/li><\/ul><\/aside><\/div><\/section><section id=\"especificaciones\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">S1 technical specifications<\/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\"><table><tbody><tr><th scope=\"row\">Type<\/th><td>Self-operated, single-seat globe valve with diaphragm actuator<\/td><\/tr><tr><th scope=\"row\">Sizes<\/th><td>DN15 to DN150<\/td><\/tr><tr><th scope=\"row\">Connections<\/th><td>EN PN16 to PN40 flanges \u00b7 ANSI 150 \/ 300 flanges \u00b7 BSP or NPT thread from \u00bd\u2033 to 2\u2033 \u00b7 Weld ends on request<\/td><\/tr><tr><th scope=\"row\">Pressure rating<\/th><td>PN25 \u2013 PN40 \u00b7 ANSI Class 150 \u2013 Class 300<\/td><\/tr><tr><th scope=\"row\">Set pressure range<\/th><td>0.5 to 15 barg, depending on actuator and springs<\/td><\/tr><tr><th scope=\"row\">Maximum differential pressure<\/th><td>16 bar (DN15\u2013DN50) \u00b7 12 bar (DN65\u2013DN80) \u00b7 10 bar (DN100)<\/td><\/tr><tr><th scope=\"row\">Kv coefficient<\/th><td>From 3.5 m\u00b3\/h (DN15) to 240 m\u00b3\/h (DN150). Reduced Kv or Cv on request<\/td><\/tr><tr><th scope=\"row\">Temperature depending on diaphragm<\/th><td>NBR: \u221220 to 80 \u00b0C \u00b7 EPDM: \u221240 to 125 \u00b0C \u00b7 EPDM + PTFE: 125 to 220 \u00b0C<\/td><\/tr><tr><th scope=\"row\">Temperature depending on seat<\/th><td>NBR: 80 \u00b0C \u00b7 EPDM or FPM: 150 \u00b0C \u00b7 PTFE + graphite: 220 \u00b0C<\/td><\/tr><tr><th scope=\"row\">Body material<\/th><td>A216 WCB carbon steel or A351 CF3M stainless steel. On request: RG10 bronze, duplex, or super duplex<\/td><\/tr><tr><th scope=\"row\">Internals<\/th><td>AISI 316L stainless steel. Double-layer stainless steel bellows<\/td><\/tr><tr><th scope=\"row\">Pressure sensing point<\/th><td>External 10 \u00d7 1 mm control line. On request, direct sensing in the body for set pressures above 1 bar<\/td><\/tr><tr><th scope=\"row\">Condensate tank<\/th><td>Required for steam and for liquids above 125 \u00b0C<\/td><\/tr><tr><th scope=\"row\">ATEX<\/th><td>II 2 GD c IIC Tx \/ c IIIC Tx\u00baC \u00b7 certificate LOM 14.034 U<\/td><\/tr><tr><th scope=\"row\">Pressure Equipment Directive<\/th><td>PED 2014\/68\/EU: the nameplate indicates whether CE marking is required<\/td><\/tr><\/tbody><\/table><\/figure><\/div><h3 class=\"wp-block-heading\">Dimensions and weight<\/h3><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\"><\/th><th scope=\"col\">DN15<\/th><th scope=\"col\">DN20<\/th><th scope=\"col\">DN25<\/th><th scope=\"col\">DN32<\/th><th scope=\"col\">DN40<\/th><th scope=\"col\">DN50<\/th><th scope=\"col\">DN65<\/th><th scope=\"col\">DN80<\/th><th scope=\"col\">DN100<\/th><th scope=\"col\">DN125<\/th><th scope=\"col\">DN150<\/th><\/tr><\/thead><tbody><tr><th scope=\"row\">Kv (m\u00b3\/h)<\/th><td>3,5<\/td><td>5<\/td><td>9<\/td><td>13,5<\/td><td>22<\/td><td>32<\/td><td>57<\/td><td>82<\/td><td>115<\/td><td>190<\/td><td>240<\/td><\/tr><tr><th scope=\"row\">Length A (EN)<\/th><td>130<\/td><td>150<\/td><td>160<\/td><td>180<\/td><td>200<\/td><td>230<\/td><td>290<\/td><td>310<\/td><td>350<\/td><td>400<\/td><td>480<\/td><\/tr><tr><th scope=\"row\">Length A (ANSI 150)<\/th><td>\u2013<\/td><td>\u2013<\/td><td>184<\/td><td>\u2013<\/td><td>222<\/td><td>254<\/td><td>276<\/td><td>298,5<\/td><td>352,5<\/td><td>\u2013<\/td><td>451<\/td><\/tr><tr><th scope=\"row\">Length A (ANSI 300)<\/th><td>\u2013<\/td><td>\u2013<\/td><td>197<\/td><td>\u2013<\/td><td>235<\/td><td>267<\/td><td>292<\/td><td>317,5<\/td><td>\u2013<\/td><td>\u2013<\/td><td>\u2013<\/td><\/tr><tr><th scope=\"row\">Height L<\/th><td>440<\/td><td>445<\/td><td>450<\/td><td>455<\/td><td>463<\/td><td>475<\/td><td>560<\/td><td>560<\/td><td>575<\/td><td>600<\/td><td>640<\/td><\/tr><tr><th scope=\"row\">Weight (kg)<\/th><td>20<\/td><td>22<\/td><td>24<\/td><td>28<\/td><td>32<\/td><td>35<\/td><td>52<\/td><td>57<\/td><td>68<\/td><td>85<\/td><td>105<\/td><\/tr><\/tbody><\/table><\/figure><\/div><p class=\"vf-note wp-block-paragraph\">Dimensions in millimeters. DN150 EN: 450 mm on request. Dimensioned drawings in the datasheet.<\/p><h3 class=\"wp-block-heading\">Set pressure ranges and actuator diameter (mm)<\/h3><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\">Range (barg)<\/th><th scope=\"col\">DN15 to DN50<\/th><th scope=\"col\">DN65 to DN100<\/th><th scope=\"col\">DN125 and DN150<\/th><\/tr><\/thead><tbody><tr><th scope=\"row\">0,5 \u2013 1,5<\/th><td>295<\/td><td>295<\/td><td>350<\/td><\/tr><tr><th scope=\"row\">1 \u2013 3<\/th><td>255<\/td><td>255<\/td><td>295<\/td><\/tr><tr><th scope=\"row\">2 \u2013 5<\/th><td>230<\/td><td>230<\/td><td>255<\/td><\/tr><tr><th scope=\"row\">4 \u2013 8<\/th><td>175<\/td><td>175<\/td><td>230<\/td><\/tr><tr><th scope=\"row\">7 \u2013 12<\/th><td>\u2013<\/td><td>175<\/td><td>175<\/td><\/tr><tr><th scope=\"row\">7 \u2013 15<\/th><td>175<\/td><td>On request<\/td><td>On request<\/td><\/tr><\/tbody><\/table><\/figure><\/div><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Exploded view and materials (22 parts)<\/summary><div class=\"wp-block-group 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\">No.<\/th><th scope=\"col\">Part<\/th><th scope=\"col\">Material<\/th><\/tr><\/thead><tbody><tr><th scope=\"row\">1<\/th><td>Body<\/td><td>A216 WCB (1.0619) \u00b7 A351 CF3M (1.4408) \u00b7 RG10 bronze<\/td><\/tr><tr><th scope=\"row\">3, 39<\/th><td>Seat holders<\/td><td>316L stainless (1.4404)<\/td><\/tr><tr><th scope=\"row\">6, 51<\/th><td>Covers<\/td><td>316L stainless; no. 6 also in steel 1.1191<\/td><\/tr><tr><th scope=\"row\">8<\/th><td>Bellows guide<\/td><td>Steel 1.0570 or 1.1191, or 316L stainless<\/td><\/tr><tr><th scope=\"row\">9, 22<\/th><td>O-rings<\/td><td>Viton<\/td><\/tr><tr><th scope=\"row\">10<\/th><td>Springs<\/td><td>Spring steel 55Si7 (1.0904)<\/td><\/tr><tr><th scope=\"row\">11<\/th><td>Ball bearing<\/td><td>Steel 100Cr6 (1.3505)<\/td><\/tr><tr><th scope=\"row\">12, 34<\/th><td>Spring supports<\/td><td>Steel 1.1191<\/td><\/tr><tr><th scope=\"row\">13<\/th><td>Adjusting nut<\/td><td>Steel 8.8<\/td><\/tr><tr><th scope=\"row\">14, 23, 24, 31, 32<\/th><td>Plate, diaphragm plate and stem, column, and bellows nut<\/td><td>Steel 1.1191<\/td><\/tr><tr><th scope=\"row\">7, 15, 16, 17, 27, 50<\/th><td>Screws and nuts<\/td><td>Steel 8.8 (screws 7 and 50 also in A2 stainless)<\/td><\/tr><tr><th scope=\"row\">18<\/th><td>Fitting<\/td><td>Brass<\/td><\/tr><tr><th scope=\"row\">19<\/th><td>Diaphragm<\/td><td>EPDM or EPDM + PTFE<\/td><\/tr><tr><th scope=\"row\">20, 26<\/th><td>Upper and lower actuator<\/td><td>Steel sheet 1.0335 with epoxy paint or AISI 316 stainless<\/td><\/tr><tr><th scope=\"row\">21, 29<\/th><td>Diaphragm screw and adjusting stem<\/td><td>AISI 304 stainless (1.4301)<\/td><\/tr><tr><th scope=\"row\">25, 25b, 42<\/th><td>Screw and nuts<\/td><td>A2 stainless<\/td><\/tr><tr><th scope=\"row\">28<\/th><td>Anti-rotation system<\/td><td>Steel 1.1191<\/td><\/tr><tr><th scope=\"row\">30<\/th><td>Bearing guide<\/td><td>AISI 304L stainless (1.4307)<\/td><\/tr><tr><th scope=\"row\">33<\/th><td>Bellows<\/td><td>Stainless steel<\/td><\/tr><tr><th scope=\"row\">35, 52<\/th><td>Gaskets<\/td><td>Metal-reinforced graphite<\/td><\/tr><tr><th scope=\"row\">40<\/th><td>Seat<\/td><td>Graphite-filled PTFE (others on request)<\/td><\/tr><tr><th scope=\"row\">45<\/th><td>Seat<\/td><td>316L stainless (1.4404)<\/td><\/tr><\/tbody><\/table><\/figure><\/div><\/div><\/details><\/section><section id=\"funcionamiento\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">How the S1 works<\/h2><p class=\"wp-block-paragraph\">The S1 works on a balance of forces between the adjusting springs and the inlet pressure acting on the diaphragm.<\/p><ol class=\"vf-steps wp-block-list\"><li><b>Set pressure.<\/b> The springs (K) compress the diaphragm (H) with the force set on the adjusting nut (F).<\/li><li><b>Valve closed.<\/b> Below the set value, the springs hold the plug against the seat.<\/li><li><b>Proportional opening.<\/b> The inlet pressure reaches the diaphragm through the control line (L). If it exceeds the set value, the valve opens in proportion to the pressure rise.<\/li><li><b>Closing.<\/b> When the pressure falls back below the set value, the springs close the valve.<\/li><li><b>Stem sealing.<\/b> The double-layer bellows (E) seals the stem; an anti-rotation system protects it.<\/li><\/ol><p class=\"wp-block-paragraph\">An excess pressure valve is not a safety valve: if you need overpressure protection, also install one of our <a href=\"https:\/\/www.valfonta.com\/en\/safety-valves\/\">safety valves<\/a>. See the <a href=\"https:\/\/www.valfonta.com\/en\/blog\/what-difference-between-safety-valve-and-relief-valve\/\">difference between a safety valve and a relief valve<\/a>.<\/p><\/section><section id=\"instalacion\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">S1 installation<\/h2><p class=\"wp-block-paragraph\">The manual recommends installing the S1 with isolation valves on both sides, a strainer, inlet and outlet pressure gauges, and, if needed, a condensate pot. It is best installed on a bypass with its own isolation valves, rejoining the main pipe downstream of the pressure sensing point.<\/p><h3 class=\"wp-block-heading\">Installation and start-up<\/h3><ol class=\"vf-steps wp-block-list\"><li><b>Clean the pipe and install a strainer<\/b> upstream of the valve to protect the seat.<\/li><li><b>Follow the arrow on the body<\/b> and install the valve in a horizontal pipe (with a slight slope if condensate is present).<\/li><li><b>Mounting position:<\/b> the standard position, with the actuator below the body, is suitable for any fluid above 0 \u00b0C; with the actuator above, only for gases and liquids up to 80 \u00b0C. Other positions are not permitted.<\/li><li><b>Support the pipe, not the valve<\/b> or the actuator: place supports close to the flanges.<\/li><li><b>Connect the control port<\/b> to the inlet pipe, at least 1 m away (or 10 \u00d7 DN), using 10 \u00d7 1 mm tubing. If the pressure fluctuates, add a needle valve.<\/li><li><b>Condensate tank<\/b> for steam or liquids above 125 \u00b0C: at the highest point, with a slight slope toward the pipe, and filled until it overflows.<\/li><li><b>Start up slowly:<\/b> with the needle valve open and the system warm, open the isolation valves gradually, inlet first.<\/li><li><b>Adjust the set pressure<\/b> with the adjusting nut (Valfonta supplies the valve preset). Compressing the spring (turning clockwise) raises the set pressure. Check it on the inlet pressure gauge.<\/li><\/ol><p class=\"wp-block-paragraph\">Installation must be carried out by specialized personnel, without exceeding the design pressure and temperature; in ATEX zones, ensure electrical conductivity with the installation. See also our guide on relief valve set pressure.<\/p><\/section><section id=\"documentacion\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">S1 technical documentation<\/h2><div class=\"wp-block-group vf-docs is-layout-flow wp-block-group-is-layout-flow\"><div class=\"wp-block-group vf-doc vf-amb-enllac is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><i>PDF<\/i><\/p><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><b>S1 datasheet (in English)<\/b><span>PDF \u00b7 6 pages \u00b7 features, exploded view, dimensions, and set pressure ranges<\/span><\/p><\/div><p class=\"vf-enllac wp-block-paragraph\"><a class=\"vf-enllac-estirat\" href=\"\/wp-content\/uploads\/2026\/10\/S1-18A-ENG.pdf\" aria-label=\"PDF S1 datasheet (in English) PDF \u00b7 6 pages \u00b7 features, exploded view, dimensions, and set pressure ranges\" target=\"_blank\" rel=\"noopener\"><\/a><\/p><\/div><div class=\"wp-block-group vf-doc vf-amb-enllac is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><i>PDF<\/i><\/p><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"vf-envolt wp-block-paragraph\"><b>Operation, installation, and maintenance manual<\/b><span>PDF \u00b7 17 pages \u00b7 installation, ATEX, troubleshooting, exploded view, and receiving<\/span><\/p><\/div><p class=\"vf-enllac wp-block-paragraph\"><a class=\"vf-enllac-estirat\" href=\"\/wp-content\/uploads\/2026\/10\/Manual-S1-18A-ESP.pdf\" aria-label=\"PDF Operation, installation, and maintenance manual PDF \u00b7 17 pages \u00b7 installation, ATEX, troubleshooting, exploded view, and receiving\" target=\"_blank\" rel=\"noopener\"><\/a><\/p><\/div><\/div><p class=\"wp-block-paragraph\">To order spare parts, give the serial number (S\/N) shown on the nameplate. Order certificates: see our <a href=\"https:\/\/www.valfonta.com\/en\/certificates\/\">quality certificates<\/a>.<\/p><\/section><section id=\"comparar\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">S1 vs. other excess pressure valves<\/h2><p class=\"wp-block-paragraph\">The range covers DN15 to DN150 and set pressures from 0.01 to 20 barg.<\/p><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\">Model<\/th><th scope=\"col\">DN<\/th><th scope=\"col\">PN<\/th><th scope=\"col\">Set pressure (barg)<\/th><th scope=\"col\">Max. T (\u00b0C)<\/th><th scope=\"col\">Steam<\/th><th scope=\"col\">Standard body<\/th><\/tr><\/thead><tbody><tr><th scope=\"row\"><a href=\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-prv53\/\">PRV53<\/a><\/th><td>15 \u2013 25<\/td><td>25<\/td><td>0,5 \u2013 15<\/td><td>150<\/td><td>No<\/td><td>CF3M stainless<\/td><\/tr><tr><th scope=\"row\"><a href=\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-prv54\/\">PRV54<\/a><\/th><td>15 \u2013 25<\/td><td>25<\/td><td>0,5 \u2013 12<\/td><td>210<\/td><td>Yes<\/td><td>CF3M stainless<\/td><\/tr><tr><th scope=\"row\"><a href=\"https:\/\/www.valfonta.com\/en\/product\/excess-pressure-valve-model-prv55\/\">PRV55<\/a><\/th><td>15 \u2013 25<\/td><td>25<\/td><td>0,01 \u2013 8<\/td><td>150<\/td><td>Yes<\/td><td>CF3M stainless<\/td><\/tr><tr><th scope=\"row\"><span class=\"vf-dato vf-dato-fila\" hidden data-vf-class=\"vf-cur\"><\/span>S1<\/th><td>15 \u2013 150<\/td><td>40<\/td><td>0,5 \u2013 15<\/td><td>220<\/td><td>Yes<\/td><td>Carbon steel or CF3M stainless<\/td><\/tr><tr><th scope=\"row\"><a href=\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s2\/\">S2<\/a><\/th><td>15 \u2013 100<\/td><td>40<\/td><td>0,02 \u2013 10<\/td><td>180<\/td><td>Yes<\/td><td>Carbon steel or CF3M stainless<\/td><\/tr><tr><th scope=\"row\"><a href=\"https:\/\/www.valfonta.com\/en\/product\/pressure-relief-valve-s3\/\">S3<\/a><\/th><td>15 \u2013 150<\/td><td>40<\/td><td>0,5 \u2013 20<\/td><td>220<\/td><td>Yes<\/td><td>Carbon steel or CF3M stainless<\/td><\/tr><tr><th scope=\"row\">S4<\/th><td>15 \u2013 100<\/td><td>40<\/td><td>0,5 \u2013 20<\/td><td>220<\/td><td>Yes<\/td><td>Carbon steel or CF3M stainless<\/td><\/tr><\/tbody><\/table><\/figure><\/div><p class=\"vf-note wp-block-paragraph\">Data from the Valfonta summary catalog (2025); S2 set pressure from its datasheet. All accept water, oil, air, and non-flammable gases.<\/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 the S1<\/h2><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Can the S1 be used as a safety valve?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">No. It must be used only as a pressure relief valve. If the installation needs overpressure protection, also install a safety device, such as our <a href=\"https:\/\/www.valfonta.com\/en\/safety-valves\/\">safety valves<\/a>.<\/p><\/div><\/details><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Can it be used with steam?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">Yes, up to 220 \u00b0C with an EPDM + PTFE diaphragm. A condensate pot must be installed to protect the diaphragm, and it must be filled until it overflows before start-up.<\/p><\/div><\/details><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>How do you adjust the set pressure?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">With the adjusting nut and a standard tool: turning clockwise compresses the spring and raises the set pressure. Valfonta supplies the valve preset to the requested value to prevent premature diaphragm failure.<\/p><\/div><\/details><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>Can it be installed in an ATEX zone?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">Yes. It carries ATEX II 2 GD category (certificate LOM 14.034 U) for zones 1 and 2 (flammable gases, vapors, and liquids) and 21 and 22 (combustible dust), according to the temperature class that corresponds to the fluid temperature.<\/p><\/div><\/details><details class=\"wp-block-details is-layout-flow wp-block-details-is-layout-flow\"><summary>What maintenance does it need?<\/summary><div class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><p class=\"wp-block-paragraph\">Periodically check the gaskets and wear parts; the frequency depends on the operating conditions. This can be done with the valve installed, depressurized, and isolated, and only with genuine spare parts.<\/p><\/div><\/details><\/section><section id=\"relacionados\" class=\"wp-block-group is-layout-flow wp-block-group-is-layout-flow\"><h2 class=\"wp-block-heading\">Other excess pressure valve models<\/h2><ul class=\"vf-rel wp-block-list\"><li><a href=\"https:\/\/www.valfonta.com\/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 relief valve\" class=\"wp-image-10230\" width=\"300\" height=\"300\" loading=\"lazy\"><b>S3 relief valve<\/b><span>Spring-loaded, up to DN150 and 20 barg set pressure.<\/span><\/a><\/li><li><a href=\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s2\/\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/ok-M2-PROVISIONAL.jpg\" alt=\"S2 excess pressure valve\" class=\"wp-image-206\" width=\"300\" height=\"300\" loading=\"lazy\"><b>S2 excess pressure valve<\/b><span>Diaphragm with internal sensing, DN15 to DN100.<\/span><\/a><\/li><li><a href=\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-prv53\/\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/ok-PRV30-44.jpg\" alt=\"PRV53 excess pressure valve\" class=\"wp-image-207\" width=\"300\" height=\"300\" loading=\"lazy\"><b>PRV53 excess pressure valve<\/b><span>CF3M stainless, DN15 to DN25, set pressure from 0.5 to 15 barg.<\/span><\/a><\/li><li><a href=\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-prv54\/\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/ok-PRV30-44.jpg\" alt=\"PRV54 excess pressure valve\" class=\"wp-image-207\" width=\"300\" height=\"300\" loading=\"lazy\"><b>PRV54 excess pressure valve<\/b><span>CF3M stainless, DN15 to DN25, steam up to 210 \u00b0C.<\/span><\/a><\/li><li><a href=\"https:\/\/www.valfonta.com\/en\/product\/excess-pressure-valve-model-prv55\/\"><img decoding=\"async\" src=\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/ok-PRV45-55.jpg\" alt=\"PRV55 excess pressure valve\" class=\"wp-image-208\" width=\"300\" height=\"300\" loading=\"lazy\"><b>PRV55 excess pressure valve<\/b><span>Set pressures from 0.01 barg, DN15 to DN25.<\/span><\/a><\/li><\/ul><\/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 the S1<\/h2><p class=\"wp-block-paragraph\">Give us your installation details and we will recommend the right size, Kv, actuator, and diaphragm 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>Size, body material, and connection type<\/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-f553-o1\" lang=\"en-US\" dir=\"ltr\" data-wpcf7-id=\"553\">\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\/product\/653#wpcf7-f553-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=\"553\" \/><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-f553-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=\"1792703057.2878237f99efe5af\" \/>\n<\/fieldset>\n<input class=\"wpcf7-form-control wpcf7-hidden\" value=\"S1\" type=\"hidden\" name=\"modelo\" \/><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><fieldset><legend>Application data (optional)<\/legend><label>Size<span class=\"wpcf7-form-control-wrap\" data-name=\"dn\"><select class=\"wpcf7-form-control wpcf7-select\" aria-invalid=\"false\" name=\"dn\"><option value=\"\">Select<\/option><option value=\"DN15 (\u00bd\u2033)\">DN15 (\u00bd\u2033)<\/option><option value=\"DN20 (\u00be\u2033)\">DN20 (\u00be\u2033)<\/option><option value=\"DN25 (1\u2033)\">DN25 (1\u2033)<\/option><option value=\"DN32 (1\u00bc\u2033)\">DN32 (1\u00bc\u2033)<\/option><option value=\"DN40 (1\u00bd\u2033)\">DN40 (1\u00bd\u2033)<\/option><option value=\"DN50 (2\u2033)\">DN50 (2\u2033)<\/option><option value=\"DN65\">DN65<\/option><option value=\"DN80\">DN80<\/option><option value=\"DN100\">DN100<\/option><option value=\"DN125\">DN125<\/option><option value=\"DN150\">DN150<\/option><option value=\"I don&#039;t know\">I don&#039;t know<\/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, compressed 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>Operating pressure (barg)<span class=\"wpcf7-form-control-wrap\" data-name=\"p_servicio\"><input size=\"40\" maxlength=\"400\" class=\"wpcf7-form-control wpcf7-text\" aria-invalid=\"false\" value=\"\" type=\"text\" name=\"p_servicio\" \/><\/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. 10 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><\/fieldset><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>","protected":false},"excerpt":{"rendered":"<p>Home\u203aPressure relief valves\u203aS1 excess pressure valve Excess pressure valve \u00b7 Diaphragm and bellows S1 excess pressure valve Up to DN150 Self-operated, single-seat excess pressure valve with a diaphragm actuator and a stem sealed by a stainless steel bellows. It limits the inlet pressure to the set value, from 0.5 to 15 barg, on steam, compressed ... <a title=\"S1 excess pressure valve\" class=\"read-more\" href=\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s1\/\" aria-label=\"Read more about S1 excess pressure valve\">Read more<\/a><\/p>\n","protected":false},"featured_media":0,"template":"","meta":{"_acf_changed":false,"_generate-full-width-content":"true","_generate-disable-headline":"true","rank_math_title":"S1 excess pressure valve up to DN150 | Valfonta","rank_math_description":"Self-operated S1 excess pressure valve with diaphragm and sealing bellows. DN15 to DN150, PN25\u2013PN40, set pressure 0.5 to 15 barg, steam up to 220 \u00b0C.","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\":\"ItemPage\",\"@id\":\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s1\/#webpage\",\"url\":\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s1\/\",\"name\":\"S1 excess pressure valve up to DN150 | Valfonta\",\"description\":\"Self-operated S1 excess pressure valve with diaphragm and sealing bellows. DN15 to DN150, PN25\u2013PN40, set pressure 0.5 to 15 barg, steam up to 220 \u00b0C.\",\"isPartOf\":{\"@id\":\"https:\/\/www.valfonta.com\/#website\"},\"about\":{\"@id\":\"https:\/\/www.valfonta.com\/#organization\"},\"inLanguage\":\"en\",\"datePublished\":\"2020-02-05T12:20:02+02:00\",\"dateModified\":\"2026-03-19T14:15:33+02:00\",\"primaryImageOfPage\":{\"@id\":\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/ok-M1-S1-3D-700x700-1.jpg\"},\"breadcrumb\":{\"@id\":\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s1\/#breadcrumb\"},\"mainEntity\":{\"@id\":\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s1\/#product\"}},{\"@type\":\"ImageObject\",\"@id\":\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/ok-M1-S1-3D-700x700-1.jpg\",\"url\":\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/ok-M1-S1-3D-700x700-1.jpg\",\"width\":\"1000\",\"height\":\"1000\",\"caption\":\"Pressure reducing valve\",\"inLanguage\":\"en\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s1\/#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\":\"ListItem\",\"position\":3,\"name\":\"S1 excess pressure valve\",\"item\":\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s1\/\"}]},{\"@type\":\"Product\",\"@id\":\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s1\/#product\",\"name\":\"S1 excess pressure valve\",\"url\":\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s1\/\",\"description\":\"Self-operated, single-seat excess pressure valve with a diaphragm actuator and a stem sealed by a stainless steel bellows. It limits the inlet pressure to the set value, from 0.5 to 15 barg, on steam, compressed air, gases, and liquids, from DN15 to DN150.\",\"brand\":{\"@type\":\"Brand\",\"name\":\"Valfonta\"},\"manufacturer\":{\"@id\":\"https:\/\/www.valfonta.com\/#organization\"},\"model\":\"S1\",\"image\":\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/ok-M1-S1-3D-700x700-1.jpg\",\"material\":\"Carbon steel A216 WCB or stainless steel A351 CF3M\",\"additionalProperty\":[{\"@type\":\"PropertyValue\",\"name\":\"Type\",\"value\":\"Self-operated, single-seat globe valve with diaphragm actuator\"},{\"@type\":\"PropertyValue\",\"name\":\"Sizes\",\"value\":\"DN15 to DN150\"},{\"@type\":\"PropertyValue\",\"name\":\"Connections\",\"value\":\"EN PN16 to PN40 flanges \u00b7 ANSI 150 \/ 300 flanges \u00b7 BSP or NPT thread from \u00bd\u2033 to 2\u2033 \u00b7 Weld ends on request\"},{\"@type\":\"PropertyValue\",\"name\":\"Pressure rating\",\"value\":\"PN25 \u2013 PN40 \u00b7 ANSI Class 150 \u2013 Class 300\"},{\"@type\":\"PropertyValue\",\"name\":\"Set pressure range\",\"value\":\"0.5 to 15 barg, depending on actuator and springs\"},{\"@type\":\"PropertyValue\",\"name\":\"Maximum differential pressure\",\"value\":\"16 bar (DN15\u2013DN50) \u00b7 12 bar (DN65\u2013DN80) \u00b7 10 bar (DN100)\"},{\"@type\":\"PropertyValue\",\"name\":\"Kv coefficient\",\"value\":\"From 3.5 m\u00b3\/h (DN15) to 240 m\u00b3\/h (DN150). Reduced Kv or Cv on request\"},{\"@type\":\"PropertyValue\",\"name\":\"Temperature depending on diaphragm\",\"value\":\"NBR: \u221220 to 80 \u00b0C \u00b7 EPDM: \u221240 to 125 \u00b0C \u00b7 EPDM + PTFE: 125 to 220 \u00b0C\"},{\"@type\":\"PropertyValue\",\"name\":\"Temperature depending on seat\",\"value\":\"NBR: 80 \u00b0C \u00b7 EPDM or FPM: 150 \u00b0C \u00b7 PTFE + graphite: 220 \u00b0C\"},{\"@type\":\"PropertyValue\",\"name\":\"Body material\",\"value\":\"A216 WCB carbon steel or A351 CF3M stainless steel. On request: RG10 bronze, duplex, or super duplex\"},{\"@type\":\"PropertyValue\",\"name\":\"Internals\",\"value\":\"AISI 316L stainless steel. Double-layer stainless steel bellows\"},{\"@type\":\"PropertyValue\",\"name\":\"Pressure sensing point\",\"value\":\"External 10 \u00d7 1 mm control line. On request, direct sensing in the body for set pressures above 1 bar\"},{\"@type\":\"PropertyValue\",\"name\":\"Condensate tank\",\"value\":\"Required for steam and for liquids above 125 \u00b0C\"},{\"@type\":\"PropertyValue\",\"name\":\"ATEX\",\"value\":\"II 2 GD c IIC Tx \/ c IIIC Tx\u00baC \u00b7 certificate LOM 14.034 U\"},{\"@type\":\"PropertyValue\",\"name\":\"Pressure Equipment Directive\",\"value\":\"PED 2014\/68\/EU: the nameplate indicates whether CE marking is required\"}],\"category\":\"Pressure relief valves\",\"subjectOf\":[{\"@type\":\"DigitalDocument\",\"name\":\"S1 datasheet (in English)\",\"url\":\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/S1-18A-ENG.pdf\",\"encodingFormat\":\"application\/pdf\"},{\"@type\":\"DigitalDocument\",\"name\":\"Operation, installation, and maintenance manual\",\"url\":\"https:\/\/www.valfonta.com\/wp-content\/uploads\/2026\/10\/Manual-S1-18A-ESP.pdf\",\"encodingFormat\":\"application\/pdf\"}]},{\"@type\":\"FAQPage\",\"@id\":\"https:\/\/www.valfonta.com\/en\/product\/pressure-excess-valve-s1\/#faq\",\"mainEntity\":[{\"@type\":\"Question\",\"name\":\"Can the S1 be used as a safety valve?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"No. It must be used only as a pressure relief valve. If the installation needs overpressure protection, also install a safety device, such as our safety valves.\"}},{\"@type\":\"Question\",\"name\":\"Can it be used with steam?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes, up to 220 \u00b0C with an EPDM + PTFE diaphragm. A condensate pot must be installed to protect the diaphragm, and it must be filled until it overflows before start-up.\"}},{\"@type\":\"Question\",\"name\":\"How do you adjust the set pressure?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"With the adjusting nut and a standard tool: turning clockwise compresses the spring and raises the set pressure. Valfonta supplies the valve preset to the requested value to prevent premature diaphragm failure.\"}},{\"@type\":\"Question\",\"name\":\"Can it be installed in an ATEX zone?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Yes. It carries ATEX II 2 GD category (certificate LOM 14.034 U) for zones 1 and 2 (flammable gases, vapors, and liquids) and 21 and 22 (combustible dust), according to the temperature class that corresponds to the fluid temperature.\"}},{\"@type\":\"Question\",\"name\":\"What maintenance does it need?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Periodically check the gaskets and wear parts; the frequency depends on the operating conditions. This can be done with the valve installed, depressurized, and isolated, and only with genuine spare parts.\"}}]}]}]"},"product_brand":[],"product_cat":[79],"product_tag":[],"class_list":["post-653","product","type-product","status-publish","product_cat-sin-categorizar","first","instock","shipping-taxable","product-type-simple"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/product\/653","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/types\/product"}],"wp:attachment":[{"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/media?parent=653"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/product_brand?post=653"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/product_cat?post=653"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/www.valfonta.com\/en\/wp-json\/wp\/v2\/product_tag?post=653"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}