| 摘要 |
<p>A valve for shutting off or closing a main fluid flow in a main flow passage (32) comprises a valve stem (28) which is actuated by a closing fluid. When the valve has reached its closed position closing fluid will be injected into a main flow passage (32) through the valve stem (28). The valve can be used for hot gas defrosting of an evaporator (1) with automatic circulation in a freezing or cooling installation, hot gas from the pressure side of a compressor (3) being used as a closing fluid. A closing of the main fluid flow in the return passage (8) and an injection of hot gas in the opposite direction is thereby obtained by means of one and the same valve, merely by opening the hot gas supply.</p> |
