Gas pressure gauge and pressure measuring method
AssigneeBalzers Aktiengesellschaft
InventorsRudolf Stocker, Walter Schaedler
Life of this patent
Estimating the term…
Abstract
A process for measuring pressure, preferably vacuum is described. The measuring signals from a heat conduction gauge and the measuring signals from a gas friction gauge are processed to a common measuring signal preferably by multiplication. They are linearly superimposed or added. The heat conduction gauge is preferably a Pirani gauge and the gas friction gauge is preferably a tuning fork quartz gauge.
Claims20
A method for measuring gas pressure, particularly at vacuum pressure levels,
- wherein said gas to be measured has a molecular mass (M),
- comprising the steps of
- deriving a first measuring signal (W) from a heat conduction gauge (11, 12, 13) exposed (15) to the gas, the pressure of which is to be measured,
- and wherein said first signal will be inversely proportional to M.sup.1/2 ;
- deriving a second measuring signal (G) from a gas friction gauge (21) exposed (15) to said gas, the pressure of which is to be measured,
- and wherein said second signal will be directly proportional to M.sup.1/2 ;
- and
- combining said first and second measuring signals to obtain a pressure output signal, in such a manner that the inverse dependency on gas molecular mass of the gas being measured by said heat conduction gauge, and reflected in said first signal, and the direct dependency on molecular mass of the gas being measured by said gas friction gauge and reflected in said second signal, will essentially, mutually, cancel each other to obtain said pressure output signal which is essentially independent of the molecular mass (M) of the gas, the pressure of which is to be measured.
A compensated gas pressure measuring gauge, providing a combined pressure output signal which is essentially independent of the molecular mass (M) of the gas, the pressure of which is to be determined,
- and especially for measuring low pressure values in the vacuum pressure level range, comprising
- a heat conduction gauge (12, 12, 13) exposed (15) to the gas, the pressure of which is to be measured, and furnishing a first signal which is inversely proportional to M.sup.1/2 ;
- a gas friction gauge (21) exposed (15) to said gas, the pressure of which is to be measured, and furnishing a second signal which is directly proportional to M.sup.1/2 ;
- and a combining circuit (3;
- W.multidot.G, W+G) coupled to receive said first measuring signal (W) and said second measuring signal (G) and combining said first and second measuring signals in such a manner that the inverse dependency of said first measuring signal on gas molecular mass, and the direct dependency of said second measuring signal on gas molecular mass effectively cancel each other to form a common output signal, which is essentially independent of the type of the gas, the pressure of which is to be measured, and hence of its molecular mass.
Dependencies are inferred from the claim text.