{"id":2598,"date":"2026-10-13T20:15:53","date_gmt":"2026-10-13T23:15:53","guid":{"rendered":"https:\/\/thermomac.com\/?p=2598"},"modified":"2026-10-13T20:15:57","modified_gmt":"2026-10-13T23:15:57","slug":"iiar-3-por-que-las-valvulas-tienen-su-propia-norma","status":"publish","type":"post","link":"https:\/\/thermomac.com\/en\/iiar-3-por-que-las-valvulas-tienen-su-propia-norma\/","title":{"rendered":"IIAR 3: Why Valves Have a Standard of Their Own"},"content":{"rendered":"

Refrigeration Insights Series. Season 3: The IIAR Standards, installment 3 of 10.<\/strong><\/p>\n\n\n\n

In an industrial refrigeration system there are hundreds of valves. Each one is a boundary: between high and low pressure, between a section that can be worked on and one that cannot, between normal operation and a leak. That is why the most repeated component in the system has an entire standard of its own: ANSI\/IIAR 3-2022, Ammonia Refrigeration Valves.<\/p>\n\n\n\n

What IIAR 3 is<\/h2>\n\n\n\n

Its purpose, in one line: to specify performance criteria for valves and strainers used in closed-circuit ammonia refrigeration systems.<\/p>\n\n\n\n

It is a product standard, not an installation standard. While IIAR 2 speaks to the engineer who designs the system and IIAR 4 to the contractor who erects it, IIAR 3 speaks above all to the manufacturer: it defines what a valve has to meet in order to be called an ammonia refrigeration valve.<\/p>\n\n\n\n

Which components it covers<\/h2>\n\n\n\n

The scope includes stop valves, control valves, check valves, ball valves, gauge valves, butterfly valves and strainers, designed and manufactured for closed-circuit mechanical ammonia refrigeration systems.<\/p>\n\n\n\n

For each family, the standard sets criteria on materials of construction, the pressure-containing envelope, allowable seat leakage, quality assurance, marking and production testing.<\/p>\n\n\n\n

That last point is key for the buyer: a valve conforming to IIAR 3 arrives marked and factory tested. The marking is the traceability that any mechanical integrity audit will later ask for.<\/p>\n\n\n\n

Two acronyms you need to master<\/h2>\n\n\n\n

The standard precisely defines two concepts that are often confused:<\/p>\n\n\n\n

MAWP (Maximum Allowable Working Pressure).<\/strong> The maximum allowable working pressure for which the equipment, component or device was designed. It is a design limit: it defines the mechanical boundary of the valve.<\/p>\n\n\n\n

MOPD (Maximum Operating Pressure Differential).<\/strong> The maximum operating pressure differential against which the valve can operate. It is a functional limit: a solenoid valve can withstand the system pressure and still be unable to open if the differential exceeds its MOPD.<\/p>\n\n\n\n

Buying a valve looking only at the MAWP and forgetting the MOPD is a classic that ends in valves that do not open when they are needed most.<\/p>\n\n\n\n

A standard that does not work alone<\/h2>\n\n\n\n

IIAR 3 is always read together with its normative references: IIAR 1 for definitions, IIAR 2 for the system design context, and ASME B31.5 for the refrigeration piping and heat transfer components those valves are welded or threaded to.<\/p>\n\n\n\n

In practice, the circuit goes like this: IIAR 2 tells you where a valve goes and what for; IIAR 3 tells you what that valve has to meet as a product; IIAR 4 tells you how to install it; and IIAR 6 will tell you how to maintain it for the next twenty years.<\/p>\n\n\n\n

What changed from 2017<\/h2>\n\n\n\n

The 2022 edition replaces the 2017 edition within the five-year review cycle that ANSI requires for all IIAR standards: each standard is reviewed at least every five years, with a public review period in which any interested party can propose changes. That consensus process is what makes these standards a reference outside the United States as well.<\/p>\n\n\n\n

The practical advice<\/h2>\n\n\n\n

When you put together your next valve order, add one line to the specification: \"conforming to ANSI\/IIAR 3-2022, with marking and production testing per the standard\". Those few words save you arguments with the supplier and leave you the documentary backing that audits will ask for.<\/p>\n\n\n\n

Next week: IIAR 4, the installation standard, where the best design can be ruined or consolidated.<\/p>\n\n\n\n

Source: ANSI\/IIAR 3-2022, Ammonia Refrigeration Valves, International Institute of Ammonia Refrigeration. Thermomac is a corporate member of the IIAR.<\/em><\/p>","protected":false},"excerpt":{"rendered":"

Serie Refrigeration Insights. Temporada 3: Las normas IIAR, entrega 3 de 10. En un sistema de refrigeraci\u00f3n industrial hay cientos de v\u00e1lvulas. Cada una es una frontera: entre alta y baja presi\u00f3n, entre un tramo que se puede intervenir y uno que no, entre una operaci\u00f3n normal y una fuga. Por eso el componente m\u00e1s […]<\/p>\n","protected":false},"author":2,"featured_media":2601,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"_joinchat":[],"footnotes":""},"categories":[16],"tags":[],"class_list":["post-2598","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-refrigeration-insights"],"_links":{"self":[{"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/posts\/2598","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/comments?post=2598"}],"version-history":[{"count":1,"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/posts\/2598\/revisions"}],"predecessor-version":[{"id":2600,"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/posts\/2598\/revisions\/2600"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/media\/2601"}],"wp:attachment":[{"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/media?parent=2598"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/categories?post=2598"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/tags?post=2598"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}