| 摘要 |
<p>Unless cooled rapidly, some products, notably factor 8 in blood plasma, lose potency. At too low a temperature, the bags in which products are contained can fail. Optimum results are achieved with a special freezer programmed to attain a time-dependent target temperature. An insulated box (1) has a normal freezer element (14) and cascade cooling spiral (16). A fan (9) provides for blast cooling. Liquid nitrogen is sprayed into the freezer via the nozzle (11). It vaporises at -196 deg.C before the gas mixture enters the inner container (6, 7) via the perforations (8) to reach the product trays (5).</p> |
