Patent ID: 6626050
Filing Date: 2003-09-30
Classification: G01F

Abstract:
A method for monitoring a flow rate in a flow sensing system, the method comprising:setting a lower flow-rate sensing level and an upper flow-rate sensing level for the flow rate; setting a first sensing period, a second sensing period and a third sensing period, wherein the flow rate is brought up during the first sensing period, the flow rate reaches a desired level during the second sensing period, and the flow rate is brought down during the third sensing period; detecting the flow rate with detecting conditions, wherein the detection conditions include that: the flow rate crosses the lower flow-rate sensing level exactly once during the first sensing period, the flow rate does not cross the lower flow-rate sensing level during the second sensing period, the flow rate crosses the lower flow-rate sensing level exactly once during the third sensing period, and the flow rate never crosses the upper flow-rate sensing level during the three sensing periods; and issuing an abnormal signal if the flow rate violates the detecting conditions.