| 摘要 |
A digital gas metering system includes inlet and outlet manifolds, a plurality of conduits each extending between the inlet manifold and the outlet manifold, and a solenoid-operated valve in each conduit. At least one of the valves is a tri-stable valve. Each tri-stable valve has a highest flow setting, a lowest flow setting, and an intermediate flow setting. The preferred embodiment utilizes at least two tri-stable valves, and these have respective highest flow settings which form a geometric progression in which each term is substantially triple the preceding term.
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