Gallons Per Minute

US customary unit to measure liquid volume discharge rate. One gallon per minute equals 0.063 liters per second (abbrev. GPM).

Galvanic Cell

A cell consisting of two dissimilar metals in contact with each other and with a common electrolyte (sometimes refers to two similar metals in contact with each other but with dissimilar electrolytes; differences can be small and more specifically defined as a concentration cell).

Galvanizing (Spelter Coating)

A plating for iron and steel composing primarily of zinc. It may be applied electronically or by dipping the pipe or casing in molten zinc (the fumes are poisonous to breathe).

Gauge Cut

The outermost projection of the excavation, measured as a diameter. The gauge cut is subject to cutter wear and to the differential cut.

Gauge Cutter

The cutter that creates the gauge cut and is subject to wear.