{"id":2593,"date":"2026-10-06T08:41:35","date_gmt":"2026-10-06T11:41:35","guid":{"rendered":"https:\/\/thermomac.com\/?p=2593"},"modified":"2026-10-06T08:41:37","modified_gmt":"2026-10-06T11:41:37","slug":"iiar-2-la-norma-madre-del-amoniaco-industrial","status":"publish","type":"post","link":"https:\/\/thermomac.com\/en\/iiar-2-la-norma-madre-del-amoniaco-industrial\/","title":{"rendered":"IIAR 2: the foundational standard of industrial ammonia"},"content":{"rendered":"

Refrigeration Insights Series. Season 3: The IIAR Standards, installment 2 of 10.<\/strong><\/p>\n\n\n\n

If you had to keep just one industrial refrigeration standard, this would be it. ANSI\/IIAR 2-2021 specifies the minimum requirements for the safe design of closed-circuit ammonia refrigeration systems. Everything else, installation, commissioning, maintenance, operation, rests on decisions made here, at the design stage.<\/p>\n\n\n\n

What it covers (and what it does not)<\/h2>\n\n\n\n

IIAR 2 applies to stationary closed-circuit vapor-compression and absorption refrigeration systems that use anhydrous ammonia as the refrigerant. Two important exclusions that the 2021 edition made explicit:<\/p>\n\n\n\n

1) It does not apply to equivalent replacements: swapping one piece of equipment for an identical one does not trigger a redesign under the new standard.<\/p>\n\n\n\n

2) It does not apply to existing installations: those remain under the codes in force at the time of their construction and under IIAR 9, which we will cover later in this series.<\/p>\n\n\n\n

The foreword itself warns of something worth repeating: the standard is not a comprehensive technical design manual and should not be used as one. It defines the floor of safety, not the ceiling of engineering.<\/p>\n\n\n\n

The architecture of the document<\/h2>\n\n\n\n

The standard is organized into four parts and 18 chapters: general provisions and definitions; design considerations affecting construction (machinery location, general requirements, machinery rooms, equipment outside the machinery room); equipment (compressors, pumps, condensers, evaporators, pressure vessels, piping, packaged systems, overpressure protection, instrumentation, ammonia detection and alarms, absorption); and appendices.<\/p>\n\n\n\n

Read straight through, it is a blueprint of every safety decision in a plant: where the machinery room goes, how it is ventilated, what detects a leak, and what happens when it does.<\/p>\n\n\n\n

Numbers worth keeping on hand<\/h2>\n\n\n\n

Ammonia has a flammability range in air of 160,000 to 250,000 ppm, an extremely high concentration compared with other flammable gases. It is part of why, when handled well, it is a safe refrigerant as well as an efficient one.<\/p>\n\n\n\n

For packaged systems installed in occupied areas, the charge must be limited so that a full discharge does not exceed 300 ppm in the room where the equipment is located. This figure is behind the engineering of the low-charge packages that are growing in the region.<\/p>\n\n\n\n

The refrigerant purity table requires ammonia at 99.5 percent minimum, oil at 50 ppm maximum, and water between 50 and 5,000 ppm. If you read our article on water in ammonia, you already know why that upper limit exists: water silently degrades evaporator performance.<\/p>\n\n\n\n

What changed in the 2021 edition<\/h2>\n\n\n\n

The 2021 edition brought adjustments that affect design directly. The most relevant ones, according to the committee itself:<\/p>\n\n\n\n

The requirements for safety showers and eyewash stations were reorganized and clarified. The ammonia detection requirements were modified based on a risk analysis. Emergency ventilation gained an additional option to reduce ventilation rates and a location exception for the exhaust. General-purpose exhaust fans no longer require discharge velocity or spark-resistant blades: the logic now is to shut them off when ammonia is detected. And filtration of makeup air was allowed under certain circumstances.<\/p>\n\n\n\n

For new plants or expansions in the region, these changes translate into concrete engineering decisions: how many detectors, where, with what interlocks, and how the machinery room ventilation is sized.<\/p>\n\n\n\n

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

If you are about to take on a new project, ask your engineering firm to state which edition of IIAR 2 it is designing to. If the answer is an old edition, or worse, none at all, that is a conversation worth having before you buy the first piece of equipment.<\/p>\n\n\n\n

Next week: IIAR 3, ammonia refrigeration valves, or why the smallest component in the system has a standard of its own.<\/p>\n\n\n\n

Source: ANSI\/IIAR 2-2021, Standard for the Safe Design of Closed-Circuit Ammonia Refrigeration Systems, International Institute of Ammonia Refrigeration. Thermomac is a corporate member of IIAR.<\/em><\/p>","protected":false},"excerpt":{"rendered":"

Serie Refrigeration Insights. Temporada 3: Las normas IIAR, entrega 2 de 10. Si tuvieras que quedarte con una sola norma de refrigeraci\u00f3n industrial, ser\u00eda esta. La ANSI\/IIAR 2-2021 especifica los requisitos m\u00ednimos para el dise\u00f1o seguro de sistemas de refrigeraci\u00f3n por amon\u00edaco en circuito cerrado. Todo lo dem\u00e1s, la instalaci\u00f3n, el arranque, el mantenimiento, la […]<\/p>\n","protected":false},"author":2,"featured_media":2595,"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-2593","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\/2593","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=2593"}],"version-history":[{"count":1,"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/posts\/2593\/revisions"}],"predecessor-version":[{"id":2594,"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/posts\/2593\/revisions\/2594"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/media\/2595"}],"wp:attachment":[{"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/media?parent=2593"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/categories?post=2593"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/thermomac.com\/en\/wp-json\/wp\/v2\/tags?post=2593"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}