The timer then opens the lower valve for a fixed period of time, permitting the - plastic powder to discharge from the intermediate chamber.

定时装置随后开启下面的夹管阀并持续一段固定的时间，让塑料粉末从中间罐腔中排出。

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They also found two kitchen timer units, two toggle switches attached to the timers in a plastic lunch-type box and a vehicle battery in the front passenger foot well.

BBC: Londonderry mortars: Two men remanded in custody