| 摘要 |
An indicating device in which a pressure transducer periodically measures loss of pressure in a pressure tank to produce an output proportional to the logarithm of the pressure loss rate since the period is constant, and a second pressure transducer continuously measures the effective tank pressure, that is the pressure difference between the tank and the ambient pressures, in mechanical values which are converted into electric logarithmic signals by means of logarithmic potentiometers to drive a dial and pointer respectively in a slide rule application of subtracting exponents, that is logarithms, to divide the effective pressure in the tank by the rate of its use to read the time remaining to depletion from a logarithmic scale numbered arithmatically as indicated on the dial by the pointer.
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