Cleanrooms and controlled environments are used for a variety of purposes, from food and drink preparation, to advanced microtechnology manufacture and surgical operations. The ability to effectively prevent contamination within these areas is heavily reliant on the performance of the HVAC system. The choice of ductwork therefore needs to be given careful consideration.
Why does Ductwork specification matter for cleanrooms?
The basic principles of a modern cleanroom are identified within ISO 14644-1:2015 which defines the space as a:
“room in which the concentration of airborne particles is controlled, and which is constructed and used in a manner to minimise the introduction, generation and retention of particles inside the room and in which other relevant parameters, e.g. temperature, humidity and pressure, are controlled as necessary”.
The standard also places cleanrooms into one of 8 classes based on the size of particles, and the number found within a cubic metre.
The ventilation system is the primary means by which both the filtration and other environmental parameters are controlled. To achieve this, High Efficiency Particulate Air (HEPA) or Ultra-Low Particulate Air (ULPA) filters are incorporated within the system. They’re also operated at an extremely high air flow rate with air changing tens or even hundreds of times per hour within the cleanroom (see CIBSE recommendations in table 2) compared with just 2 or 3 times per hour within a conventional living space.
Building Type | Ventilation Strategy | Recommended Ventilation Rate |
Clean Room | Mechanical Ventilation | 10-120 ACH for non-laminar-flow clean room depending on type of work |
Table 2. Recommended minimum ventilation rates from CIBSE Guide B2 (2016)
With potentially hundreds of metres of ductwork required for larger cleanrooms, specifiers need a solution which can reliably meet these exacting standards. The Kingspan KoolDuct System provides a modular alternative to conventional sheet metal ductwork. Its panels are formed from rigid phenolic insulation faced with aluminium and when fabricated into ductwork can offer several notable advantages for these high specification applications.
Controlling airflow
The increased air circulation rate within cleanroom systems means that the airtightness of ductwork can have a significant impact on overall performance. The sealing methods used to fabricate Kingspan KoolDuct sections, in combination with the patented jointing system used to connect them, allows air loss to be significantly reduced when compared with conventional systems. In a comparative study on two identical properties, the air-leakage rate from The Kingspan KoolDuct System was shown to be 79% lower than that of a sheet metal system insulated with glass mineral fibre. In practice, this means that airflow volumes can be reliably met with smaller, more efficient fans. This can help to significantly reduce long-term energy demand and running costs.
The airtight design of the ductwork sections is particularly beneficial for cleanrooms designed to be kept at positive pressure. This approach ensures air is forced out of the clean room in the event of a breach, reducing the risk of contamination. Ductwork fabricated from The Kingspan KoolDuct System can allow positive pressurization up to 1000 Pascal. Its design also ensures that pressure drops along the ductwork are less common than with conventional sheet metal systems.
The premium performance insulation core of the panels also helps to reduce heat loss through the ductwork. This is particularly beneficial in clean room applications as typically around 95% of air is recirculated. By ensuring this recirculated air is effectively insulated, the system energy demand can be reduced. This can provide notable cost savings for applications such as food preparation areas which must be maintained at cooler temperatures.
Preventing contamination
In addition to maintaining the flow of air to the cleanroom, the design of The Kingspan KoolDuct System also helps to ensure the air is still “clean” when it reaches the room. The insulation core material is fibre free, reducing the risk of loose fibres entering the ductwork. The flow is instead directed over the internal aluminium surface – eliminating the risk of rust.
KoolDuct panels and sealant have also passed an extensive 60-day test as part of the UL 181 Standard for Factory-Made Air Ducts and Air Connectors. This verifies that the components are
highly resistant to the spread of mould and the effects of high humidity.
In practice
The advantages of the Kingspan KoolDuct System were clearly visible in an installation as part of an ISO Class 8 cleanroom at E-liquid manufacturer, Zeus Juice UK.
The construction of the cleanroom was overseen by specialist designers, Monmouth Scientific Ltd. The firm used the Kingspan KoolDuct System as part of a combined on and offsite construction approach as Operations Director, David Court, explained:
“We chose Kingspan KoolDuct for the air-distribution ductwork, which we designed to the pressure value of 500 Pa. In addition to its excellent system performance, we are able to easily fabricate the panels in a wide variety of shapes and sizes using our computer numerical control (CNC) router. The product was fabricated in accordance with guidance from Kingspan, ensuring we could take full advantage of the product’s flexibility to fit specific applications and ensure the ductwork as airtight.
Complex shapes were constructed off-site, but most of the material was delivered to site flat packed and ready for assembly. This allowed us to save on significant transport costs.”
Once onsite, the ductwork sections could be quickly fabricated and installed in long-runs with a single fix. This supported a fast-track construction, allowing the cleanroom to be quickly commissioned.
A premium specification
The exacting tolerances for cleanroom spaces mean that it is vital that all sections of the HVAC system are performing at their optimum. The Kingspan KoolDuct System has been proven to provide a simple and effective solution for these applications, maintaining air flow with lower energy demand than conventional sheet metal ductwork.
