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INVOLVED STANDARDS HVAC requirements for a medical facility are well-regulated in the local bylaws , regulations , and standards . In South Africa , SANS 10400 covers the minimum requirements for airflow and air changes per hour for various medical applications and also makes allowance for rational design and assumption , as well as adopting of other internationally recognised best practices or standards .
“ Further to SANS 10400 , a number of local and international documents guide the HVAC design for such facilities – the primary source for design criteria being the ASHRAE standard 170 , as it is the most developed document available . Other reference documents have been compiled for this purpose and include the Infrastructure Unit Supply System ( IUSS ), the Centre for Scientific and Industrial Research ( CSIR ), R158 , British Standards ( HTM ), and Federation of European Heating , Ventilation and Air Conditioning Associations ( REHVA ),” notes Jonker Bester , director at Spoormaker & Partners .
Each room type in a medical facility will need to comply to a particular ISO classification ( also still referred to as a federal standard ). These classifications are according to the ‘ cleanliness ’ level of the air inside the room by the quantity and size of particles per volume of air , and also refer to the maximum particle concentration limits allowed .
The ISO classification system includes classes : ISO-1 , ISO-2 , ISO-3 , ISO-4 , ISO-5 , ISO-6 , ISO-7 , ISO-8 and ISO-9 . ISO-1 being the ‘ cleanest ’ class and ISO-9 is the ‘ dirtiest ’ class ( for reference ISO 9 is still ‘ cleaner ’ than any regular room or space ).
The Federal Standard equivalent for these ISO classes are FS 100000 ; 10000 ; 1000 ; 100 ; 10 ; and 1 . This standard was essentially replaced in 1999 by the new ISO classification but is still referred to world-wide in design specifications .
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UV-GI is of little consequence if ventilation is inadequate .
“ Introducing fresh air into a space and exhausting air out of a space also needs careful consideration .”
GENERAL HVAC CONSIDERATIONS
“ Although split wall units may have their place in a medical |
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facility environment , they are not ideal for most applications |
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and are erroneously included because of three main factors : |
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they cannot introduce the necessary fresh air into a space , |
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they have no means to filter the re-circulated air that may be |
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contaminated , and they are known to collect bacteria and |
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moulds internally ,” notes Schaefer . |
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Looking at the different ISO / FS classifications , |
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predominantly in South African medical theatres , laminar flow |
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designs which are on the ‘ quite clean ’ scale environments , are |
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the most commonly installed . |
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“ Intensive care units ( ICUs ) can be safely air conditioned with |
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high air changes and reduced filtration or reduced air changes |
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and increased filtration . Dilution in such an environment is key . |
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Here , we would aim 6 ACH and for anything up to 12 ACH in |
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www . hvacronline . co . za |
RACA Journal
I May 2021
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19 |