New Hybrid AHU System for Operating Theatres
By Dato ' Ir . Dr Hj Abu Hashim Abd Ghani Director , Perunding Hashim & Neh Sdn Bhd
Azrin bin Abd Razak Senior Associate Director , Perunding Hashim & Neh Sdn Bhd
Heating , Ventilation and Air-conditioning ( HVAC ) systems for hospital applications need special attention in terms of temperature and humidity control in order to provide a clean environment , prevent wound infection , bacteria growth plus provide a comfortable environment for surgeons and operating theatre teams to work in .
Operating Theatres ( OTs ) have to be designed with a positive over pressure at all times in the range of 10 % and 15 % of air volume , as this will effectively prevent micro-organisms infiltrating into the OT .
The special considerations required for the design of an OT are : a . Temperature regulation ; b . Humidity control ; c . Space Pressurisation ; d . Supplied Air Filtration ; and e . Effective Air Delivery and Distribution . A well designed system will provide a healthy environment , minimise airborne transmission of viruses , bacteria , fungus spores and other micro aerosols , and reduce the impact of the building and its processes on the OT environment .
The purpose of this article is to explore new technologies for the design of HVAC systems for OT applications , being mindful of : a . Environmental Comfort ; b . Infection Control ; c . Energy Conservation ; d . Safety of Lives ; and e . Operational Maintenance .
Operating Theatre Requirements
For critical areas such as OTs , comfort is a secondary issue , the moisture content in the air
Top - Operating theatre in Malaysia Below ( Picture 1 ) Fungus growth , ( Picture 2 ) Bacteria and mould growth
is critical . Most bacteria , fungus or moulds thrive best within certain range of temperature and humidity conditions .
The challenges for heating , ventilation , airconditioning and refrigeration ( HVACR ) engineers include designing system solutions for OT applications that are energy efficient , provide clean air , with low moisture content and can be maintained at a constant room temperature . OT design criteria are :
Outside Air Temperature :
Room Temperature :
DB 34 ° C / WB 28 ° C
DB 18 ° C ± 1 ° C Relative Humidity : 50 % ± 5 %
Moisture Content : 0.006-0.007kg / kg Dry Air Refer to Psychrometric Chart Figure 1 shaded area .
FEATURE
27