Key Air Handling Unit Features for Healthcare Facility Hygiene and Safety

Clean and hygiene environment in a health care facility is the major objective for top quality health services. Hospitals may spread infections, when standard procedures are not followed. Staff, patients and visitors are always prone to acquiring infections. Air handling units are used to create controlled conditions in a facility. Concentration of pathogens is diluted with the help of AHU operation. These units provide necessary ventilation air and filter room air to clean inside supply air. Clean environment in health care facilities reduces cost and treatment time. Workers performance improves with better indoor conditions. Patient recovery is fast. Indoor time of patients is reduced.

Economical selection of AHU demands special care for unit selection, processes involved and quality of materials. Health care unit includes quite a few additional components when compared to conventional units. Basic functions include in addition to temperature and humidity controls, isolation of working spaces with air flow streams and reduction of pathogen count. Filtration, noise reduction and heat recovery functions are also performed at AHU level. A prime criterion for selection of technologies performing above mentioned functions is the cleanliness and hygiene environment. Materials selected preferably are cleanable types which are easy to disinfect. System component are kept accessible and close to view. Filter conditions are regularly monitored and inspected. A schedule is developed to inspect, clean and replace filters. A dirty filter chokes system air flow in addition to consuming more fan power.

Operating hours for units are variable. Sometimes it may require continuous operation for long hours. Partial loads are also experienced. Air flow balancing is required at all working conditions. Plug fans with VFD drive is optimum choice for these types of units. These fans are without belts. In case of belt driven fans, belt material from worn out belts gets mixed with supply air. These impurities in supply air compromise indoor air quality. Plug fans are direct driven fans without any risk of belt wear and tear. VFD operation provides precise control for air flow balancing. At part load air flow may be reduced. At dirty filter conditions, motor rpm may be increased to get required cfm of air. This is done with touch of a button as compared to belt tightening in case of conventional system.

As high volumes of outside air are involved in health care air handling operation, heat recovery arrangement is built with the unit. This may be rotor, plate or loop type. Rotor type is avoided due to risk of cross contamination.

Materials and thicknesses are selected with minimum leakages and body deflection. Leakages may occur at casing joints and filter or damper locations. Thermal features and bridges are selected to get maximum performance and high efficiency. Modular design is easy to fit and transport. Sections are assembled at site location. These are easy to rig and move through doors as compared to fully assembled units. Structure and insulation is selected for high performance. Proper insulation in corner pieces provides efficient thermal bridge. Sturdy structures and frames provide vibration free equipment. According to earthquake zone of the project, snubbers are provided along the base channel. These provide three dimensional restraints in case of seismic activity. For normal operation, vibration isolation from building structure is provided through base foundation. When equipment is placed above occupied space, noise transmission reduction steps are always required. For severe seismic zones, seismic cables are used to restraint movement in case of seismic activity.

Quite a few control components are involved for operation of healthcare AHU. Complete factory installations of control and instruments save time and effort at site. Controls need to be compatible with building management system. Open protocols like BACNET and LON are used for this purpose. Operation of the AHU is monitored at central control. Management of maintenance, operation and hygiene conditions becomes easy with central monitoring.