| 摘要 |
PCT No. PCT/US96/14432 Sec. 371 Date Mar. 10, 1998 Sec. 102(e) Date Mar. 10, 1998 PCT Filed Sep. 11, 1996 PCT Pub. No. WO97/12215 PCT Pub. Date Apr. 3, 1997A gas flow detector (10) includes a casing (12) with an inlet (14) for connection to a gas source and an outlet (16) for connection to a gas using appliance. Between the inlet and outlet there is an internal chamber (18) which receives a sleeve (24). Gas flow from the inlet (14) to the outlet (16) around the sleeve (24) is prevented by a seal (22) which encircles the sleeve (24). A piston (38) having a magnet (44) mounted at the lower end thereof moves in the sleeve (24) from a lower position (as illustrated) to an upper position. The piston (38) drops under gravity to its lower position when there is no gas flow. It lifts to its upper position as soon as there is gas flow. A magnetically operated switch (54) is provided below the position that the magnet (44) occupies when the piston (38) is in its lower position. |
