| 摘要 |
PCT No. PCT/EP89/01373 Sec. 371 Date Aug. 27, 1990 Sec. 102(e) Date Aug. 27, 1990 PCT Filed Nov. 15, 1989 PCT Pub. No. WO90/05895 PCT Pub. Date May 31, 1990.The invention concerns a volumetric device with reciprocating piston to deliver defined quantities of liquid and includes a piston valve pump and a valve block with intake and discharge valves affixed to a reservoir. The nullify the pressure difference generated upon withdrawing liquid from the hermetically sealed reservoir between this reservoir and the ambient atmosphere, the valve head additionally is provided with a ventilation valve allowing on one hand the inflow of ambient air into the reservoir and on the other hand preventing the escape of the tiniest amounts of liquids even after lengthy standing.
|
