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We offer several different duct collar adaptor options to fit your specific cleanroom airflow requirements. One of the most critical aspects of the cleanroom design is ensuring adequate airflow to the fan filter modules, while maintaining the specified temperature conditions for your process. Many HVAC systems are not large enough to feed all the supply air needed to achieve the air change rates for the given ISO levels to be achieved. In a single-pass design, fan filter units can be utilized to satisfy the ACH requirement, but in a re-circulating design where critical temperature control must be achieved, HVAC duct adaptors must be implemented to ensure the fan filter units do not starve for air.
Standard HEPA duct filter collars for attachment to any of our fan filter units is available in both 10” and 12” collar sizes. No pre-filters can be used with this adaptor. They come standard in galvanized finish, but white powder coat finish is available.
The side load pre-filter duct adaptor allows the pre-filter to be changed from the side of the unit. This is beneficial for maintenance personnel, as they can simply reach over from an adjacent tile and slide the pre-filter out easily. The duct does not have to be disconnected to remove the pre-filter in this design. Please note this duct adaptor also adds 1-1/2” to the height of the fan filter unit.
This model allows the pre-filter to be kept in place on top of the fan filter motor housing to increase the life span of the main HEPA filter. However, this type of duct adaptor still requires the pre-filter to be changed out from above. Please note this adaptor also adds 1 -1/2” to the height of the fan filter unit.
The standard mixing box duct adaptor is the best solution for creating a closed loop system without a plenum cap design. The supply from the HVAC unit is connected to one side of the adaptor and the return from the cleanroom is connected to the other creating a re-circulating air flow system. This ensures the fan filter will get the adequate cooling into the cleanroom without starving the fan motor. This is a 50/50 bypass design and is a cost-effective way to utilize fan filters without the expense of upsizing your HVAC system or having to build a plenum cap above the cleanroom.
For applications where an existing HVAC system is not large enough to provide the supply air needed to each fan filter unit, an air conditioning mixing box can be placed on top of the fan filter intake to supplement air from the ambient surrounding space. The pre-filter is located on the mixing box to remove the major dust particles from the make-up air stream. This provides 50% cooling with 50% ambient air mixed into the fan filter supply intake. This design ensures the fan filter unit will not starve for air do to inadequate supply from your HVAC. The trade off is that you will only be introducing 50% of the cooling capacity of your HVAC system into the cleanroom space.
There are many different HVAC duct adaptors and collars available to meet specific requirements, so please contact one of our specialists to make sure you are purchasing the correct duct adaptor for your application.