| 摘要 |
A magnet valve (V), a coupling unit (K) and a gas detector (G) are provided, the latter monitoring concentrations of gas in the surrounding atmosphere. When concentrations exceed a given value, a signal is received by the coupling unit (K) which in turn interrupts current supply to the valve so that it cuts off the gas flow. A spring is fitted to the valve so that it causes valve closure when electrical current supply decreases. The valve has two magnet coils, one (M2) of which has a greater resistance than the other (M1). The coil with the lower resistance is connected momentarily when the valve opens, and that with the higher resistance is connected to maintain the valve in the open position as long as the coil is magnetised. A circuit (T2,R2) measures the detector alarm level, monitoring its current usage which increases when it gives an alarm. |
