Abstract
HEPA filters are widely used for air cleansing in hospital wards for operatory and blood disease patients. In recent years need has been felt for a convenient and small bioclean room, and the HEPA filter has come to be attached to a compact air purifier in actual clinical environments.
We have studied a small air purifier, “Enviracaire”, equipped with a HEPA filter (abbreviated E.V.C.) in a series of basic experiments on dust removal and bacterial elimination capacity. We obtained the following conclusions.
1. The wind velocity of the E.V.C. at high speed operation was 0.4 m/sec and the wind volume was 0.07m/sec.
2. When box A was installed on the dispersion outlet of the E.V.C, for the purpose of shutting off the flow of contaminated air from other parts, removal of dust particles under 0.42-0.62μm was 99.97-99.99%, and of particles over 0.62 pm, 100%. The weight of dust particles was 100% in all cases. Air-borne bacteria were removed 100% in all cases. Even when a high concentration of Serratia marcescens was sprayed into the air, removal was 100 % as observed by a SY type pinhole sampler (the SY method).
3. When box A was removed and experiments were conducted as in actual conditions, at the center of the E.V.C. outlet dust particles over 0.62μm were found at distances greater than 50 cm. Particle weight also increased at distances greater than 50cm. With the SY method removal at different distances was 75.0-100%, and with the HV method removal was 69.7-100% with 15 minute suction, 64.3-100% with 30 minute suction, and 78.4-100% with 60 minute suction. At distances less than 60cm the existance of bacteria was quite small.
4. It is to be concluded that though this apparatus is highly effective in removal of dust and bacteria and, in the future, may have practical application.
