| 摘要 |
A method for measuring the volume of cavities, in which the cavity is evacuated and the volume is subsequently determined by the admission of air, is proposed together with a device suitable for carrying out this method. In this case, the cavity is evacuated to a pressure which is higher than the water vapour pressure, dependent on temperature, and lower than 500 mbar. A limited quantity of air is then admitted via a metering valve (8), and in this way a rise in pressure is produced to a value which is likewise still less than 500 mbar. In order to determine the volume in accordance with the formula V = Q. DELTA t/ DELTA p, the time is measured in which this pressure change takes place. Before admission of the air, it is possible to undertake monitoring for the presence of leaks, by temporarily switching off the vacuum pump when the pressure is higher than the water vapour pressure and observing the pressure change occurring in this time. Finally, before measuring the volume of the cavity it is possible to undertake evacuation of the cavity down to the water vapour pressure, in order to establish the presence of hidden accumulations of water. If the latter are present, it is expedient not to terminate the evacuation until the water vapour pressure is undershot, in order to dry out the accumulations of water. <IMAGE>
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