{"id":5710,"date":"2023-08-01T08:39:00","date_gmt":"2023-08-01T06:39:00","guid":{"rendered":"https:\/\/www.idro-elettrica.it\/esperto-risponde\/how-should-installations-involving-multiple-main-fire-pumps-be-constructed\/"},"modified":"2026-07-01T09:47:19","modified_gmt":"2026-07-01T07:47:19","slug":"how-should-installations-involving-multiple-main-fire-pumps-be-constructed","status":"publish","type":"esperto-risponde","link":"https:\/\/www.idro-elettrica.it\/en\/esperto-risponde\/how-should-installations-involving-multiple-main-fire-pumps-be-constructed\/","title":{"rendered":"Multiple Main Fire Pumps: Requirements for 2 and 3 Pumps"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\"><em>Having more main fire pumps<\/em> means, first and foremost, complying with the specific requirements set forth in UNI EN 12845 (Section 10.2) when installing two or three main pumps. In this response, we clarify the rules, typical scenarios, and operational conclusions. <\/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=\"#contesto-cosa-dice-la-uni-en-12845-art-10-2\">Context: What does UNI EN 12845 (Section 10.2) say?<\/a><\/li><li class=\"\"><a href=\"#piu-pompe-principali-antincendio-requisiti-generali-uni-en-12845\">Multiple Main Fire Pumps: General Requirements (UNI EN 12845)<\/a><\/li><li class=\"\"><a href=\"#funzionamento-in-parallelo-perche-la-curva-q-h-deve-coincidere\">Parallel Operation: Why the Q\/H Curve Must Match<\/a><\/li><li class=\"\"><a href=\"#installazione-con-due-pompe-cosa-devono-garantire\">Installation with Two Pumps: What They Must Ensure<\/a><\/li><li class=\"\"><a href=\"#installazione-con-tre-pompe-cosa-devono-garantire\">Installation with Three Pumps: What They Must Ensure<\/a><\/li><li class=\"\"><a href=\"#alimentazione-singola-vs-alimentazione-singola-superiore-cosa-cambia-davvero\">Single-channel vs. superior single-channel: What&#8217;s the Real Difference?<\/a><\/li><li class=\"\"><a href=\"#motore-elettrico-e-motore-diesel-regole-pratiche-senza-ambiguita\">Electric Motors and Diesel Engines: Practical Rules (Without Ambiguity)<\/a><\/li><li class=\"\"><a href=\"#schema-di-verifica-rapida-checklist-operativa\">Quick Verification Checklist (Operational Checklist)<\/a><\/li><li class=\"\"><a href=\"#conclusione\">Conclusion<\/a><\/li><\/ul><\/nav><\/div>\n\n<h2 id=\"contesto-cosa-dice-la-uni-en-12845-art-10-2\" class=\"wp-block-heading\">Context: What does UNI EN 12845 (Section 10.2) say?<\/h2>\n\n<p class=\"wp-block-paragraph\">The applicable standard is <strong>UNI EN 12845<\/strong>, and specifically, Section <strong>10.2<\/strong> addresses <strong>systems with multiple pumps<\/strong>. There are four requirements to consider (in summary): <\/p>\n\n<ol class=\"wp-block-list\">\n<li>The pumps must be capable of <strong>operating in parallel<\/strong> at all possible flow rates.<\/li>\n\n\n\n<li>If <strong>two pumps<\/strong> are installed, each must deliver <strong>100% of the design flow rate<\/strong> at <strong>the design head<\/strong>.<\/li>\n\n\n\n<li>If <strong>three pumps<\/strong> are installed, each must be capable of delivering <strong>50% of the required flow rate<\/strong> at <strong>the design head<\/strong>.<\/li>\n\n\n\n<li>When more than one pump is installed in a <strong>superior or dual-feed system<\/strong>, <strong>no more than one<\/strong> may be driven by an <strong>electric motor<\/strong>.<\/li>\n<\/ol>\n\n<p class=\"wp-block-paragraph\">These four rules should be read together: they define both the required Hydraulic Performance and the constraints on motorization in certain scenarios.<\/p>\n\n<h2 id=\"piu-pompe-principali-antincendio-requisiti-generali-uni-en-12845\" class=\"wp-block-heading\">Multiple Main Fire Pumps: General Requirements (UNI EN 12845)<\/h2>\n\n<p class=\"wp-block-paragraph\">The key point when discussing multiple pumps is their <strong>compatibility for parallel operation<\/strong>. It\u2019s not enough to simply \u201cinstall two (or three) pumps\u201d; they must be able to work together at the flow rates specified for the system. <\/p>\n\n<p class=\"wp-block-paragraph\">This leads to the following operational conclusion: to meet the parallel operation requirement, <strong>all<\/strong> <strong>main pumps<\/strong> must have <strong>the same Q\/H characteristic curve<\/strong>.<\/p>\n\n<p class=\"wp-block-paragraph\">In practice, the design of the pump group must be consistent from the outset: the selection of pumps is not independent, because parallel operation is an explicit requirement.<\/p>\n\n<h2 id=\"funzionamento-in-parallelo-perche-la-curva-q-h-deve-coincidere\" class=\"wp-block-heading\">Parallel Operation: Why the Q\/H Curve Must Match<\/h2>\n\n<p class=\"wp-block-paragraph\">The proposed summary is clear: to meet the requirement for parallel operation \u201cat all possible flow rates,\u201d the pumps must share the <strong>same Q\/H curve<\/strong>.<\/p>\n\n<p class=\"wp-block-paragraph\">This passage links directly to:<\/p>\n\n<ul class=\"wp-block-list\">\n<li>the <strong>regulatory requirement<\/strong> (parallel operation);<\/li>\n\n\n\n<li>the <strong>technical choice<\/strong> (same characteristic curve).<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\">If the curves are not consistent with one another, it becomes difficult (or uncontrollable) to ensure parallel operation within the intended operating range. For this reason, verification of the Q\/H curve is treated as an enabling condition, not as a detail. <\/p>\n\n<h2 id=\"installazione-con-due-pompe-cosa-devono-garantire\" class=\"wp-block-heading\">Installation with Two Pumps: What They Must Ensure<\/h2>\n\n<p class=\"wp-block-paragraph\">When <strong>TWO<\/strong> pumps are installed, the rule to follow is clear: <strong>each<\/strong> must deliver <strong>100% of the design flow rate<\/strong> at <strong>the design head<\/strong>.<\/p>\n\n<p class=\"wp-block-paragraph\">The operational conclusion, in the case of <strong>a single power supply<\/strong>, is as follows:<\/p>\n\n<ul class=\"wp-block-list\">\n<li>Both pumps <strong>must<\/strong> each deliver <strong>100%<\/strong> of the design flow rate;<\/li>\n\n\n\n<li>Both <strong>can<\/strong> be powered by <strong>an electric motor<\/strong>.<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\">The following also remains true: <strong>there is no prohibition<\/strong> against using <strong>diesel-powered<\/strong> main pumps, so the use of diesel is possible in this scenario as well.<\/p>\n\n<h2 id=\"installazione-con-tre-pompe-cosa-devono-garantire\" class=\"wp-block-heading\">Installation with Three Pumps: What They Must Ensure<\/h2>\n\n<p class=\"wp-block-paragraph\">When <strong>THREE<\/strong> pumps are installed, the basic rule changes: <strong>each pump<\/strong> must be capable of delivering <strong>50% of the required flow rate<\/strong> at <strong>the design head<\/strong>.<\/p>\n\n<p class=\"wp-block-paragraph\">The practical conclusion, in the case of <strong>a single power supply<\/strong>, is:<\/p>\n\n<ul class=\"wp-block-list\">\n<li>All three pumps <strong>must<\/strong> each deliver <strong>50%<\/strong> of the design flow rate;<\/li>\n\n\n\n<li>All three <strong>can<\/strong> be powered by <strong>an electric motor<\/strong>.<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\">The same note applies here: it is always possible to use <strong>diesel-powered<\/strong> main pumps, if deemed appropriate.<\/p>\n\n<h2 id=\"alimentazione-singola-vs-alimentazione-singola-superiore-cosa-cambia-davvero\" class=\"wp-block-heading\">Single-channel vs. superior single-channel: What&#8217;s the Real Difference?<\/h2>\n\n<p class=\"wp-block-paragraph\">The most significant difference among the cases described is not in terms of flow rate or head (which remains as noted above for 2 or 3 pumps), but rather in the constraints related to <strong>the electric motor<\/strong> when moving to a higher \u201ctype\u201d of power supply.<\/p>\n\n<p class=\"wp-block-paragraph\">In the case of <strong>a single upper power supply<\/strong>, the following rule applies: <strong>only one<\/strong> pump can be driven by <strong>an electric motor<\/strong>.<\/p>\n\n<p class=\"wp-block-paragraph\">This translates as follows:<\/p>\n\n<ul class=\"wp-block-list\">\n<li>With <strong>two<\/strong> main pumps:\n<ul class=\"wp-block-list\">\n<li>Each one must provide <strong>100%<\/strong> of the design flow rate;<\/li>\n\n\n\n<li><strong>only one<\/strong> can be electric;<\/li>\n\n\n\n<li>The other one <strong>must<\/strong> be powered by <strong>a diesel engine<\/strong>.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>With <strong>three<\/strong> main pumps:\n<ul class=\"wp-block-list\">\n<li>Each one must provide <strong>50%<\/strong> of the design flow rate;<\/li>\n\n\n\n<li><strong>only one<\/strong> can be electric;<\/li>\n\n\n\n<li>The other two <strong>must<\/strong> be powered by <strong>diesel engines<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\">Furthermore, it is reiterated that <strong>there is nothing<\/strong> to <strong>prevent<\/strong> the use of <strong>only<\/strong> diesel-powered main pumps.<\/p>\n\n<h2 id=\"motore-elettrico-e-motore-diesel-regole-pratiche-senza-ambiguita\" class=\"wp-block-heading\">Electric Motors and Diesel Engines: Practical Rules (Without Ambiguity)<\/h2>\n\n<p class=\"wp-block-paragraph\">To summarize the above, the restrictions on engines depend on the type of fuel:<\/p>\n\n<ul class=\"wp-block-list\">\n<li><strong>Single power supply<\/strong>:\n<ul class=\"wp-block-list\">\n<li>with 2 pumps: both can be <strong>electric<\/strong>;<\/li>\n\n\n\n<li>with 3 pumps: all of them can be <strong>electric<\/strong>;<\/li>\n\n\n\n<li>However, the <strong>diesel fuel<\/strong> can still be used.<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Single top feed<\/strong>:\n<ul class=\"wp-block-list\">\n<li>In presence of multiple main pumps, <strong>only one<\/strong> can be <strong>electric<\/strong>;<\/li>\n\n\n\n<li>the rest must be <strong>diesel<\/strong>;<\/li>\n\n\n\n<li>You can also select the \u201call diesel\u201d option.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\">This approach avoids the most common mistake: applying the constraint to the electric motor even when it is not required, or ignoring it when it is actually mandatory.<\/p>\n\n<h2 id=\"schema-di-verifica-rapida-checklist-operativa\" class=\"wp-block-heading\">Quick Verification Checklist (Operational Checklist)<\/h2>\n\n<p class=\"wp-block-paragraph\">Before considering the issue \u201cresolved,\u201d verify that the installation consistently complies with the following points:<\/p>\n\n<ul class=\"wp-block-list\">\n<li>The pumps are designed to <strong>operate in parallel<\/strong> at the expected flow rates.<\/li>\n\n\n\n<li>The main pumps have the <strong>same Q\/H characteristic curve<\/strong>.<\/li>\n\n\n\n<li>With <strong>2 pumps<\/strong>: each delivers <strong>100% of the design flow rate<\/strong> at <strong>the design head<\/strong>.<\/li>\n\n\n\n<li>With <strong>3 pumps<\/strong>: each provides <strong>50% of the required flow rate<\/strong> at <strong>the design head<\/strong>.<\/li>\n\n\n\n<li>If the power supply is <strong>single-phase<\/strong>: <strong>only one<\/strong> pump can be powered by <strong>an electric motor<\/strong>.<\/li>\n\n\n\n<li>The use of <strong>a diesel engine<\/strong> is permitted and, in certain cases, is <strong>required<\/strong> for one or more pumps.<\/li>\n<\/ul>\n\n<h2 id=\"conclusione\" class=\"wp-block-heading\">Conclusion<\/h2>\n\n<p class=\"wp-block-paragraph\">Systems with <em>multiple main fire pumps<\/em> can only be configured correctly if the following factors are considered together: parallel operation (and thus consistency of the Q\/H curve), the required performance for 2 or 3 pumps (100% or 50% at design head), and motor constraints in cases of a single, higher-rated power supply.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Multiple main fire pumps: Here\u2019s how to properly configure systems in accordance with UNI EN 12845. Let\u2019s take a look at what changes when there are 2 or 3 pumps and what restrictions apply to electric and diesel engines. <\/p>\n","protected":false},"featured_media":5711,"parent":0,"template":"","meta":{"_acf_changed":false,"_angie_page":false,"footnotes":"","_members_access_role":[],"_members_access_error":""},"tags":[695,634,552,1204,1203,1202,736,607,549],"class_list":["post-5710","esperto-risponde","type-esperto-risponde","status-publish","has-post-thumbnail","hentry","tag-design-flow-rate","tag-diesel-engine","tag-fire-pumps","tag-parallel-operation","tag-project-scope","tag-pumping-units","tag-q-h-curve","tag-sprinkler-systems","tag-uni-en-12845"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.idro-elettrica.it\/en\/wp-json\/wp\/v2\/esperto-risponde\/5710","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\/5710\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.idro-elettrica.it\/en\/wp-json\/wp\/v2\/media\/5711"}],"wp:attachment":[{"href":"https:\/\/www.idro-elettrica.it\/en\/wp-json\/wp\/v2\/media?parent=5710"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.idro-elettrica.it\/en\/wp-json\/wp\/v2\/tags?post=5710"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}