Glossary and index of fluid power principles and components

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

G

GAIN
Ratio of increase in a signal (or measurement) as it passes through a control system or a specific control element. If a signal gets smaller, it is said to be attenuated.

GALVANIC CORROSION
Corrosion that occurs on the less noble of two dissimilar metals in direct contact with each other in an electrolyte, such as water, sodium chloride in solution, sulfuric acid, etc.

GAS BOTTLE
See BACK-UP BOTTLE.

GASKET
A seal, made from rubber or other synthetic material in the shape of a circle and of polygonal cross-section. See O-RING.

GATE VALVE
A two-way valve that may be opened or closed to block the flow of fluid in a passage. Normally manually operated, but may be automated, especially for larger sizes. Normally designed so that when open, the opening of the passage is not restricted, but there will be some small pressure loss. See GLOBE VALVE and NEEDLE VALVE.

GAUGE PRESSURE
A term used to state that any pressure stated is corrected for atmospheric pressure. Normally abbreviated psig (pounds per square inch gauge)

GLAND
A mechanical device that is used to contain a seal, o-ring or gasket in a specified space to result in a leak-proof connection between two or more mechanical components.

GLOBE VALVE
A two-way valve that may be opened or closed to block the flow of fluid in a passage. Normally manually operated, but may be automated, especially for larger sizes. Normally designed so that the flow of fluid must make a non-straight turn inside the valve body which results in a loss of pressure across the valve when open, which is greater than the loss across a gate valve. See GATE VALVE and NEEDLE VALVE.

GROUND
A point of zero reference in electrical circuits to which all circuit voltages are compared. Also, to ground a device means to make connections to an earth ground for safety purposes.