Patent ID: 8640522

Claim:
A self-test system for a paddle-type flow detector, the system comprising: an arm, the arm being used to displace a trip stem from a first position to a second position wherein said trip stem is biased to said first position and said flow detector indicates flow when said trip stem is in said second position; a first sensor, the first sensor detecting when said trip stem is in said first position; a second sensor, the second sensor detecting when said trip stem is in said second position; wherein, when said trip stem is in said second position, said arm releases said trip stem and said trip stem returns to said first position because of said biasing; wherein, said self-test system determines the amount of time between when said first sensor stops detecting said trip stem and said second sensor detects said trip stem after said arm releases said trip stem; and wherein based on said amount of time, said self-test system determines if a paddle is attached to said trip stem.