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Effective cooling and air management are vital for clean rooms . " Generally , you need an air handler . Standard hardware units are often insufficient for the precise airflow and air changes required in clean rooms . Custom-built air handlers are essential to meet these specific needs . The air handler is designed based on conditions such as humidity control , cooling capacity , airflow and fan size . It goes through a comprehensive engineering process ," he explains .
The choice of cooling systems involves several considerations . " There are different options for generating the heating or cooling requirements in the space ," Rennie notes . Options include DX units , VRF condensers or chillers , each with its own set of advantages and applications . However , not all cooling methods are suitable for clean rooms . " Evaporative cooling , which uses wetted media , is not acceptable for these highly controlled environments because it introduces particles into the airstream ," Rennie points out .
Evaporative cooling , while energy-efficient , is generally unsuitable for highly controlled clean room environments . " Evaporative cooling systems are water-hungry and have a short lifespan due to mineral buildup and other issues . This method also introduces particles into the air stream , which is unacceptable in sterile environments .”
Humidity control is a vital aspect of clean room environments . " Humidity can be controlled through heating and cooling . We pass air through a coil to absorb moisture and then reheat it . For extreme dehumidification , specialised dehumidifiers with desiccant wheels are integrated into the system . These systems can achieve sub-25 % humidity levels , which is necessary for manufacturing certain products that are highly hygroscopic ," he adds . Although these systems are expensive and complex , they are essential to prevent moisture absorption during the manufacturing process .
The location of a facility significantly influences the choice of HVAC systems . " If you ' re building a low-energy facility , you should consider the geographic location because the size of the equipment needed can vary drastically ," Rennie notes . Coastal areas , for example , pose challenges for cooling systems due to higher humidity levels .
VALIDATION AND COMPLIANCE Once a clean room facility is constructed , it undergoes a rigorous validation process . " Validation is where we test our design against the URS . This phase involves comprehensive testing , including particle counts and temperature mapping . We perform detailed particle count tests after the facility is built but before the client takes over . This includes filter integrity or DOP testing and recovery tests to ensure compliance with regulatory standards ."
Clients also conduct microbial testing to measure the levels of micro-organisms in the environment . " These tests are highly structured and form the basis for obtaining a license to
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operate the facility . If you don ' t pass the validation , you don ' t get your license .
" After the initial validation , maintaining the facility involves regular monitoring and filter changes ," he adds . The Building Management System ( BMS ) plays a key role in ongoing maintenance by providing real-time data and alerts .
Selecting the appropriate HVAC equipment is a critical aspect of clean room design . Rennie outlines several factors that influence these decisions , such as budget , availability , and the specific needs of the facility . " We have established relationships with various suppliers as well as manufacturing our own range of AHUs , allowing us to choose the best systems for each project ," he notes . The choice of equipment is tailored to ensure optimal performance and compliance with industry standards .
COOL BREEZE AIRCONDITIONING WEIGHS IN ON EVAPORATIVE COOLING As businesses and industries increasingly prioritise sustainability and cost-effectiveness , evaporative cooling emerges as a viable alternative to traditional air conditioning systems .
“ With evaporative cooling you would change the air in a particular space around 30 times an hour – so essentially bringing in new air and removing the stale air . The rate of air change can vary depending on the varying circumstances . This concept of cooling differs from conventional air-conditioning which relies on air recirculation to get to the temperature required ,” says Stuart Karovsky , general manager at Air-Dale Engineering ( Cool Breeze Airconditioning SA ) which has been in this business since 1964 .
For this reason , evaporative cooling has emerged as a contender , particularly for large spaces like warehouses and commercial buildings .
" Evaporative cooling offers significant advantages , especially for cooling expansive areas with high ceilings or roofs . Compared to conventional air conditioning , it presents a more economical solution in terms of both upfront capital costs and ongoing operational expenses ," argues Karovsky .
Stuart Karovsky , general manager at Air-Dale Engineering ( Cool Breeze Airconditioning SA ).
www . refrigerationandaircon . co . za RACA Journal I July 2024 23