{"id":7888,"date":"2020-07-28T15:51:00","date_gmt":"2020-07-28T13:51:00","guid":{"rendered":"https:\/\/www.idro-elettrica.it\/esperto-risponde\/inlet-filters-2-mandatory-cases-uni-en-12845\/"},"modified":"2026-07-01T09:46:00","modified_gmt":"2026-07-01T07:46:00","slug":"inlet-filters-2-mandatory-cases-uni-en-12845","status":"publish","type":"esperto-risponde","link":"https:\/\/www.idro-elettrica.it\/en\/esperto-risponde\/inlet-filters-2-mandatory-cases-uni-en-12845\/","title":{"rendered":"Inlet filters: 2 mandatory cases (UNI EN 12845)"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><em>Inlet filters<\/em> and main fire pumps: a practical question, but one with direct implications for installation. Let\u2019s see <strong>when<\/strong> they are required and <strong>where<\/strong> they should be installed, as specified in <strong>UNI EN 12845 9.3.6<\/strong>. <\/p>\n\n<div class=\"wp-block-rank-math-toc-block\" id=\"rank-math-toc\"><h2>Table of Contents<\/h2><nav><ul><li class=\"\"><a href=\"#quando-si-parla-di-filtri-in-aspirazione-contesto-della-domanda\">When it comes to inlet filters (context of the question)<\/a><\/li><li class=\"\"><a href=\"#il-riferimento-uni-en-12845-9-3-6\">Reference: UNI EN 12845 9.3.6<\/a><\/li><li class=\"\"><a href=\"#filtri-in-aspirazione-con-aspirazione-soprabattente-quando-sono-obbligatori\">Inlet Filters with Overhead Inlet: When Are They Required?<\/a><\/li><li class=\"\"><a href=\"#filtri-in-aspirazione-con-aspirazione-sottobattente-quando-sono-richiesti\">Intake Filters with Under-Cowl Inlet: When They Are Required<\/a><\/li><li class=\"\"><a href=\"#dove-installare-i-filtri-in-aspirazione-a-monte-e-allesterno\">Where to Install Inlet Filters: \u201cUpstream\u201d and \u201cOutside\u201d<\/a><\/li><li class=\"\"><a href=\"#valvole-e-intercettazione-cosa-va-previsto-insieme-al-filtro\">Valves and Shut-Off Devices: What to Include Along with the Filter<\/a><\/li><li class=\"\"><a href=\"#errori-tipici-da-evitare-in-base-alle-indicazioni-presenti\">Common Mistakes to Avoid (Based on the Guidelines Provided)<\/a><\/li><li class=\"\"><a href=\"#conclusione-in-breve\">Conclusion (in brief)<\/a><\/li><\/ul><\/nav><\/div>\n\n<h2 id=\"quando-si-parla-di-filtri-in-aspirazione-contesto-della-domanda\" class=\"wp-block-heading\">When discussing inlet filters (context of the question)<\/h2>\n\n<p class=\"wp-block-paragraph\">The requirement is clear: <strong>when filters must be installed<\/strong> on the <strong>inlet lines<\/strong> of the <strong>main fire pumps<\/strong>.<\/p>\n\n<p class=\"wp-block-paragraph\">In the context of plumbing practice, a filter is not \u201calways necessary\u201d: it depends on <strong>the<\/strong> pump\u2019s <strong>inlet conditions<\/strong> and, in one specific case, also on the type of tank (open tank).<\/p>\n\n<h2 id=\"il-riferimento-uni-en-12845-9-3-6\" class=\"wp-block-heading\">Reference: UNI EN 12845 9.3.6<\/h2>\n\n<p class=\"wp-block-paragraph\">The referenced standard is <strong>UNI EN 12845 9.3.6<\/strong>.<\/p>\n\n<p class=\"wp-block-paragraph\">According to these guidelines, <strong>inlet filters<\/strong> must be installed in two distinct and mutually exclusive scenarios:<\/p>\n\n<ul class=\"wp-block-list\">\n<li><strong>whenever<\/strong> the pumps are <strong>installed above the sump<\/strong> (with the filter positioned in a specific way relative to the sump valve);<\/li>\n\n\n\n<li><strong>only<\/strong> in the case of <strong>open tanks<\/strong>, when the pumps are <strong>operating below the liquid level<\/strong> (with precise instructions on where to install the filter and with a shut-off valve between the tank and the filter).<\/li>\n<\/ul>\n\n<h2 id=\"filtri-in-aspirazione-con-aspirazione-soprabattente-quando-sono-obbligatori\" class=\"wp-block-heading\">Inlet Filters with Overhead Inlet: When Are They Required?<\/h2>\n\n<p class=\"wp-block-paragraph\">In the case of <strong>above-door inlet<\/strong>, the requirement is clear: <strong>inlet filters must always be installed<\/strong>.<\/p>\n\n<p class=\"wp-block-paragraph\">Furthermore, it\u2019s not enough to simply \u201cinstall a filter\u201d; <strong>the installation location<\/strong> is also specified. The filter: <\/p>\n\n<ul class=\"wp-block-list\">\n<li><strong>It must be installed upstream of the bottom valve<\/strong>.<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\">This information is crucial for anyone who needs to inspect an existing system or properly set up an installation plan: the location is not a matter of choice, but is an integral part of the relevant regulatory requirement.<\/p>\n\n<h2 id=\"filtri-in-aspirazione-con-aspirazione-sottobattente-quando-sono-richiesti\" class=\"wp-block-heading\">Intake Filters with Under-Cowl Inlet: When They Are Required<\/h2>\n\n<p class=\"wp-block-paragraph\">In the case of <strong>under-cabinet inlet ventilation<\/strong>, the response is more selective.<\/p>\n\n<p class=\"wp-block-paragraph\"><strong>Inlet filters<\/strong> are installed <strong>only on open tanks<\/strong>. Therefore: <\/p>\n\n<ul class=\"wp-block-list\">\n<li>it is not indicated as \u201calways\u201d for all sub-beats;<\/li>\n\n\n\n<li>It is explicitly linked to<strong>the \u201copen tank\u201d<\/strong>condition.<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\">In addition to \u201cwhen,\u201d \u201chow\u201d and \u201cwhere\u201d are also specified:<\/p>\n\n<ul class=\"wp-block-list\">\n<li>The filter <strong>must be installed on the inlet pipe<\/strong>;<\/li>\n\n\n\n<li>The filter <strong>must be located outside the tank<\/strong>.<\/li>\n<\/ul>\n\n<h2 id=\"dove-installare-i-filtri-in-aspirazione-a-monte-e-allesterno\" class=\"wp-block-heading\">Where to Install Inlet Filters: \u201cUpstream\u201d and \u201cOutside\u201d<\/h2>\n\n<p class=\"wp-block-paragraph\">The two operational guidelines that govern the installation are:<\/p>\n\n<ul class=\"wp-block-list\">\n<li><strong>\u201cupstream of the check valve\u201d<\/strong> (overflow scenario);<\/li>\n\n\n\n<li><strong>\u201coutside the tank\u201d<\/strong> (under-tank scenario with an open tank).<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\">In practice, the answer isn&#8217;t just a simple &#8220;yes or no&#8221; to the filter, but it also clarifies that:<\/p>\n\n<ul class=\"wp-block-list\">\n<li>In the upper chamber, the connection to the <strong>bottom valve<\/strong> is part of the installation;<\/li>\n\n\n\n<li>In the case of a sub-hanger with <strong>an open reservoir<\/strong>, the \u201cexternal\u201d placement is an explicitly required specification.<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\">If you are revising a floor plan or layout, use these two guidelines as a reference for positioning the component in the inlet.<\/p>\n\n<h2 id=\"valvole-e-intercettazione-cosa-va-previsto-insieme-al-filtro\" class=\"wp-block-heading\">Valves and Shut-Off Devices: What to Include Along with the Filter<\/h2>\n\n<p class=\"wp-block-paragraph\">In the specific case of <strong>open tanks<\/strong> that supply <strong>submersible<\/strong> pumps, a dedicated shut-off valve is required in addition to the filter.<\/p>\n\n<p class=\"wp-block-paragraph\">It is stated that:<\/p>\n\n<ul class=\"wp-block-list\">\n<li><strong>A shut-off valve must be installed between the tank and the filter<\/strong>.<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\">Therefore, in the basic configuration described, the components are not \u201cjust filters\u201d: the <strong>shut-off valve<\/strong> is part of the configuration required in that case.<\/p>\n\n<p class=\"wp-block-paragraph\">For the inlet <strong>above the sump<\/strong>, on the other hand, the <strong>bottom valve<\/strong> is used as a positioning reference (with the filter located \u201cupstream\u201d of it).<\/p>\n\n<h2 id=\"errori-tipici-da-evitare-in-base-alle-indicazioni-presenti\" class=\"wp-block-heading\">Common Mistakes to Avoid (Based on the Guidelines Provided)<\/h2>\n\n<p class=\"wp-block-paragraph\">Without adding any requirements not mentioned here, there are some \u201clogical\u201d errors that this answer helps prevent:<\/p>\n\n<ul class=\"wp-block-list\">\n<li><strong>Confusing the two cases<\/strong>: treating the lower and upper beams as if they followed the same rules.<\/li>\n\n\n\n<li>In <strong>the upper chamber<\/strong>, install the filter without following the instruction to install it<strong>\u201cupstream of the bottom valve<\/strong>.\u201d<\/li>\n\n\n\n<li>In <strong>the sub-tank with an open reservoir<\/strong>, place the filter <strong>inside<\/strong> the reservoir, even though it is supposed to be placed <strong>outside<\/strong>.<\/li>\n\n\n\n<li>In <strong>the open-tank sub-valve<\/strong>, install the filter but <strong>omit<\/strong> the <strong>shut-off valve<\/strong> between the tank and the filter.<\/li>\n<\/ul>\n\n<h2 id=\"conclusione-in-breve\" class=\"wp-block-heading\">Conclusion (in brief)<\/h2>\n\n<p class=\"wp-block-paragraph\"><strong>Inlet filters<\/strong> on main fire pumps are required in the following cases: <strong>always<\/strong> for <strong>above-head<\/strong> pumps (with a filter <strong>upstream of the foot valve<\/strong>) and <strong>only<\/strong> for <strong>below-head<\/strong> pumps in the case of <strong>open tanks<\/strong> (with an <strong>external<\/strong> filter and <strong>a shut-off valve<\/strong> between the tank and the filter), in accordance with <strong>UNI EN 12845 9.3.6<\/strong>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Inlet filters: When are they really necessary on the inlet lines of main fire pumps? In this answer, we summarize the cases specified in UNI EN 12845 9.3.6 and explain where to install filters and shut-off valves. <\/p>\n","protected":false},"featured_media":7892,"parent":0,"template":"","meta":{"_acf_changed":false,"_angie_page":false,"footnotes":"","_members_access_role":[],"_members_access_error":""},"tags":[558,620,552,612,617,615,614,613,549],"class_list":["post-7888","esperto-risponde","type-esperto-risponde","status-publish","has-post-thumbnail","hentry","tag-bottom-valve","tag-engineering-insight","tag-fire-pumps","tag-inlet-filters","tag-ministerial-decree-37-2008","tag-open-tanks","tag-overhead-inlet","tag-under-the-bed-vacuuming","tag-uni-en-12845"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.idro-elettrica.it\/en\/wp-json\/wp\/v2\/esperto-risponde\/7888","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.idro-elettrica.it\/en\/wp-json\/wp\/v2\/esperto-risponde"}],"about":[{"href":"https:\/\/www.idro-elettrica.it\/en\/wp-json\/wp\/v2\/types\/esperto-risponde"}],"version-history":[{"count":0,"href":"https:\/\/www.idro-elettrica.it\/en\/wp-json\/wp\/v2\/esperto-risponde\/7888\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.idro-elettrica.it\/en\/wp-json\/wp\/v2\/media\/7892"}],"wp:attachment":[{"href":"https:\/\/www.idro-elettrica.it\/en\/wp-json\/wp\/v2\/media?parent=7888"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.idro-elettrica.it\/en\/wp-json\/wp\/v2\/tags?post=7888"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}