| 摘要 |
In medical apparatus, an accurate and quickly responding metering is required for admixing anesthetic gases. The gas pressure must not be a disturbing factor. A gas metering device comprises a metering unit connected to the gas source and delivering the metered gas through an outlet. A control is effected through an electrically operated control unit having a desired value input section and a display section. The gas enters into an inlet buffer of the metering unit and passes therefrom into a pressure space and simultaneously, through a change -over valve 11 in normal position, into a measuring space. In its switched position, a change over valve establishes connection to the outlet. In the outlet line a switch valve is provided closing in its normal position and opening in its switched position. The pressure space and the measuring space are connected to each other through a differential pressure sensor. With the two valves in normal position, the measuring space is filled with gas up to a desired pressure, for bringing the valves into their switched positions in which the gas volume flows to the outlet. With the pressure drop thereby obtained, the valves reassume their normal positions.
|
