GB1069632A - Improvements in and relating to methods and systems of ventilating for reducing the spread of airborne infection - Google Patents

Abstract

1,069,632. Ventilating. UNION CARBIDE CORPORATION. Oct. 29, 1963, No. 42566/63. Heading F4V. [Also in Division H5] In a method of ventilating for reducing the spread of airborne infections, air is sterilized by means of ultra-violet radiation and circulated through a zone, while the pressure in the zone is maintained at a value different from that of the exterior of the zone. As shown, rooms 23-29 in a hospital ward are supplied with air from a sterilizing unit 35 via ducts 36-45 and ceiling-mounted distributers 46-54, air being withdrawn from the rooms through outlets in the floor and recirculated to unit 35 at such a rate that the pressure in the rooms is greater than that outside. Air leaking from the rooms into corridors 21, 22 is recirculated to unit 35 which also receives outside air and may be connected in a heating or air-conditioning system. Rooms 30-32 have ceiling distributers 30a-32a connected to a separate sterilizing unit, while rooms 33, 34 are provided with individual sterilizing units 58, 59 which are arranged to take in room air at floor level and discharge sterilized air towards the ceiling (Fig. 4, not shown). Fresh air is supplied to, and stale air withdrawn from, rooms 33, 34 at rates sufficient to maintain the desired overpressure therein. The sterilized air may be supplied to and withdrawn from the rooms through inlets and outlets mounted respectively at the top and bottom of one wall and connected to a sterilizing unit individual to but external of the room (Figs. 6 and 7, not shown). In highly infectious areas, such as operating theatres, the pressure therein is maintained below that of the surrounding areas to prevent the escape of airborne infection (Fig. 8, not shown). A more concentrated stream of air may be directed over an operating table by providing a relatively large opening (95, Fig. 9, not shown) in the ceiling directly above the table or by connecting a flexible hose (104, Fig. 10, not shown) to the duct (102) supplying sterilized air. Alternatively a portable sterilizing unit (133) having a flexible discharge conduit (134) may be employed. The sterilizing units (Fig. 3, not shown) may comprise an inlet duct (122), a fan (120), a filter (121), a plurality of chambers (111, 112, 113) containing ultra-violet generating tubes (114, 115, 116) and helical baffles (117, 118, 119), and an outlet duct (123). The chambers may be of rectangular, circular or hexagonal cross-section.