Normally, the valve opens for only a few seconds when you swallow.

When valve opens free movement of water and air is possible.

A valve in the side of the cylindrical affair opened and a figure dropped out, stood looking at them.

Empty ones should have their valves opened and be stored well away from any sources of heat.

As with a diode, a small pressure difference is needed before the valve opens.

It was nothing to worry about, but Lawrence could not help wondering what would happen if the valve opened under the pressure from beneath.

I knew that the valve had never opened itself.

He felt that valves opened for him and closed behind him.

If no, make sure the valve can open to let air through from the pump.

When the valve opens, the air can either leave or come into the lung.