| 摘要 |
<p>Apparatus is described for controlling delivery of dangerous material, such as LPG, from a tanker 12 to a tank 14, through a pipe 16. A valve 18 is controlled by an arrangement 22. An operator 28 carries a radio transmitter 24 and must periodically transmit an appropriate signal to the control 22, otherwise the control 22 will time out and close the valve, also sounding an alarm. In accordance with the invention, the transmitter 24 is also provided with a timer, having a shorter count down time, and also re-set when the signal is sent to the control 22. The timer in the transmitter 24 alerts the operator 28 that a signal should be sent, giving the operator an opportunity to send a signal before the control 22 closes the valve 18. However, if the operator does not send a signal, or is incapable of doing so, the timer at 22 will assume that an emergency situation exists, and cease further delivery. <IMAGE></p> |
