Waterthief

Weston—300 feet 1½ inch hose; 50 feet 2½ inch hose; one flasher; one siamese waterthief; one foam extinguisher.

An example is the waterthief (klepsydra). This is a tube, of which one (bottom) end is held under water, and which becomes full of water by sucking the air out of it at the other (top) end.

The APC Tank was capable of delivering three mediums of extinguishing agents via a valved “Waterthief” three-way appliance that was connected to the P-250 pump.

The most common control loop is called the feedback control loop. Feedback control is as old as civilization, or at least 1000 years old. Figure 17.8 shows a klepshydra, which is ancient Greek for "waterthief"!