| 摘要 |
<p>Device for ventilation and/or bleeding of underground liquid fuel storage tanks comprises an air pipe which allows atmospheric pressure equilisation, with a secondary ventilation device closed by an overpressure safety valve. Pref. the secondary ventilation device branches off from the connecting pipe of the air pipe at the storage tank and the overpressure safety vavle can be adjusted w.r.t. closing pressure which is higher than the back pressure which occurs at max. tank filling speed, partic. due to friction in the air pipe. The movable valve body pref. has a sealing surface of PTFE, lined with an inlay of resilient material which is resistant to mineral oil and vapours e.g. chloroprene or acrylonitrile rubber. The device allows safer operation during filling, is easy to mfr. and requires little maintenance.</p> |
