Gas mixing apparatus for respirator
First Claim
1. A method of mixing two gases together in controlled proportions, comprising the steps of:
- controlling the supply of a first gas to a mixing chamber by providing a first orifice of a first variable area for supplying the first gas to the mixing chamber, the first variable area comprising a series of orifice areas corresponding to a geometrical progression having a predetermined progression ratio;
controlling the supply of a second gas to a mixing chamber by providing a second orifice of a second variable area for supplying the second gas to the mixing chamber, the second variable area comprising a series of orifice areas corresponding to the same geometrical progression as the first orifice area;
controlling the ratio between the areas of the first and second orifices according to a selected mixing ratio; and
varying the sizes of the two orifices during mixing in response to change in pressure drop across the two orifices while maintaining the same preset mixing ratio.
1 Assignment
0 Petitions
Accused Products
Abstract
A gas mixing valve has first and second inlet chambers linked to supplies of a first and second gas, and a mixing chamber having a blended gas outlet. The inlet chambers are connected to the mixing chamber via first and second control valves, each valve having a valve seat and valve member with opposing surfaces defining a flow control orifice. Each valve seat and valve member are relatively movable between a closed position in which no flow occurs and a maximum opening position to define a series of orifices of progressively increasing area corresponding to the same geometrical progression. The position of each valve member can be controlled to provide a desired mixing ratio. Each valve seat is provided in a respective piston, and the pistons are tied together to move in response to variations in pressure drop across each piston, in order to vary the orifice size to compensate for changes in flow rate without changing the mixing ratio.
185 Citations
3 Claims
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1. A method of mixing two gases together in controlled proportions, comprising the steps of:
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controlling the supply of a first gas to a mixing chamber by providing a first orifice of a first variable area for supplying the first gas to the mixing chamber, the first variable area comprising a series of orifice areas corresponding to a geometrical progression having a predetermined progression ratio; controlling the supply of a second gas to a mixing chamber by providing a second orifice of a second variable area for supplying the second gas to the mixing chamber, the second variable area comprising a series of orifice areas corresponding to the same geometrical progression as the first orifice area; controlling the ratio between the areas of the first and second orifices according to a selected mixing ratio; and varying the sizes of the two orifices during mixing in response to change in pressure drop across the two orifices while maintaining the same preset mixing ratio. - View Dependent Claims (2, 3)
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Specification