Air handling systems

Air handling system, OT interior & OT equipments. There are several options available in each part from where options are selected as per need, choice & budget. OT being most critical area in a hospital complex, it is necessary to control OT air in respect of temperature, humidity & particulate matter content of air, micro-organisms, i.e. bacteria, viruses, fungi etc.

Air handling systems process air through various stages. Air is cooled, moisture is removed, air is filtered to remove dust particles, bacteria, viruses; some air handling systems additionally remove gases, odors and other volatile organic compounds.

Laminar Air Flow is non-turbulent air flowing in parallel lanes vertically. LAF is filtered air coming over operative area from diffuser plenum above it. Plenum is fitted with HEPA (High Efficiency Particulate Air) filters of 0.3micron at 99.99% efficiency. Many times it is seen that plenum also works as light source above operative area; it has CFL/LED lights inside which provide clear shadow less light over operative area.

It is necessary to maintain particular air velocity in LAF so that filtered air coming over operative area carries bacterial load away from it. According to international standards it should be between 90-120 FPM (feet per minute). NABH (National Accreditation Board for Hospitals & Healthcare) also recommends the same.

Highly clean air of LAF falls in CLASS 100/ISO 5 category. When this air moves further in OT after leaving LAF area it mixes with less clean air of the room along with heat, moisture, bacterial load carried from operative area. It gradually looses it's clean state and while it reaches the last point in OT from where it is sent back to Air Handling Unit. Air in peripheral area of LAF normally falls in CLASS 10,000 - 100,000 categories depending on Air Handling Unit & OT size.

LAF can be made in various sizes. Apart from these standard sizes any other customized size can also be made.

Air Handling Unit has 3 filtration stages in total. First is 10 micron pre-filter, second 5micron fine-filter and third 0.3 micron HEPA filter. Out of three, first two are fitted in Air Handling Unit and last i.e. HEPA is fitted in plenum above operative area.

Fresh air is added to this within AHU. Positive pressure is created to restrict outside air entering OT though door etc. Necessary cascade pressure relief dampers are provided in wall to relieve excess pressure in hermetically sealed areas.

Air conditioning is done within Air Handling Unit to provide required cooling; no extra a/c is required in OT apart from this. HEPA plenum can be made in GI powder coat, Aluminum powder coat, SS304.

• 1.1. Type of Casing : Double Skin Polyurethane Foamed, Floor Mounted
• 1.2. Casing Details : Inner casing - 1.0 mm Aluminum / SS316 , Outer Skin : GI - 1.0 mm Power Coated
• 1.3. PUF Insulation Thickness : For outdoor Application 45mm Thick , 40 Kg/ m3 Density & for Indoor Application 25 mmThick,38 Kg/m3 Density.
• 1.4. Cooling Coil : 6 rows deep Copper Tube, Fins - Al. 12-13 FPI, Copper Tube Thickness shall be Minimum 0.5 mm.
• 1.5. Coil Casing-(Top/Side/Bottom ) : SS316
• 1.6. Drain Pan Material : SS 316
• 1.7. Drain Pan Insulation : 19mm Thick, Closed cell Nitrile Rubber,50 Kg/m3 Density.
• 1.8. Filter Frame where the Filter will be mounted : shall be Aluminum Heavy Gauge.
• 1.9. Pre-Filter & Microvee Filter Frame Material : Aluminum.
• 1.10. Fan : DIDW backward curved Centrifugal fan. 90 mm of water static pressure. Make : CG / Nikotra / Kruger.
• 1.11. Motor : Suitable for 415 + 10% volts, 50 cycle, 3 phase AC supply.
• 1.12. Fan & Motor Mounting : Heavy gauge Aluminum.
• 1.13. AHU Mouth Damper & Flange : Aluminum.
• 1.14. Provision will be made so that AHU cooling unit can be bypassed when required. For outdoor Application Thermal Break profile is recommended.