Hot Mix Glossary
There are 402 entries in this glossary.G
| Term | Definition |
|---|---|
| gas |
A state of matter which is neither solid or liquid. Matter in a gaseous state is highly compressible. It has relatively low density and viscosity and undergoes relatively great expansion and contraction with changes in pressure and temperature. |
| gas stream |
The flow of hot gasses produced by the aggregate drying process. The gas stream flows through the dryer and baghouse carrying combustion gases from the burner plus dust and steam from the drying process. The baghouse exhaust fan pulls in combustion air for the burner of the aggregate dryer and causes the gases to flow. |
| gate valve |
A type of control valve commonly used in hydraulic and pneumatic circuits to shut off flow. A gate, similar to a guillotine, moves to close passage through the valve as it is actuated. Most gate valves used at HMA plants are manually operated, requiring multiple turns of a wheel on a threaded shaft. Gate valves are sometimes used in piping of hot oil heaters and asphalt storage tanks. They can be used in lines for hot oil, asphalt, fuel oil, or gas. However, they are not recommended for use in lines carrying liquid that normally contains foreign matter or debris that can accumulate in their grooved seats and prevent complete shut off. When used for asphalt, the valve usually has a hot oil jacket. Pneumatic or hydraulic actuating cylinders cannot be used to operate a gate valve. |
| gear pump |
A type of positive displacement pump widely used in the HMA industry. It displaces a liquid by reducing the volume between its parts as they rotate. If the displaced liquid encounters resistance that equals or exceeds the force created by the pump, the pump normally continues to displace the liquid, increasing its pressure until it opens a relief valve to bypass the liquid back into the supply line. Compare centrifugal pump. |
| glad hands |
Quick disconnect air hose connectors on a truck tractor. The connectors facilitate connecting air brake lines from the tractor to a trailer. |
| globe valve |
A type of control valve commonly used in hydraulic and pneumatic circuits to regulate flow. It has a globe-shaped plug that moves to restrict the flow as its spindle is actuated. Most globe valves used at HMA plants are manually operated, requiring multiple turns of a wheel on a threaded shaft. A variety of configurations and plug shapes are available. Some plugs are conical-shaped. Others are parabolic-shaped. Globe valves are used in piping for hot oil heaters. They can be used in lines for thermal fluid (hot oil), fuel oil or gas. They are not recommended for piping carrying liquid asphalt. Pneumatic or hydraulic actuating cylinders cannot be used to operate a globe valve. |
| gooseneck |
The forward end of a semitrailer that steps up from the main chassis. It has a tow pin that extends down vertically and connects to the fifth wheel of a tractor. |
| gpm |
Abbreviation for gallons per minute. |
| graphics panel |
An optional panel that graphically pictures the major components of a HMA facility and the status or operating state of key controls. Although much of the same information can be determined from the standard control panels, a graphics panel is faster and easier to comprehend. |
| grated |
A surface (usually for walking) that incorporates a steel grating. (See grating.) |
| grating |
The floor commonly used for work platforms on HMA equipment. It is usually a grill or network of steel bars that provides a non-slippery walking surface and does not collect water and dust. |
| gravity chute |
A chute that feeds material by gravity. Entry and exit chutes of dryers are usually gravity chutes. However, slinger feeders are sometimes used instead of gravity entry chutes. (See slinger feeder.) |
| gravity take-up |
A mechanism for taking up slack in a conveyor belt to control its tension. The mechanism uses a weight suspended from disk pulleys. This type of take-up is used on long conveyors and on conveyors that incorporate weigh belts. Belt tension on other conveyors is controlled by adjusting the tail pulley. The gravity take-up mechanism has advantages over tail pulley adjustment. The gravity take-up mechanism has a wider range of adjustment and automatically maintains tension despite belt stretch. |
| grizzly |
(See bar grizzly.) |
| GTR |
Ground tire rubber. Sometimes mixed with virgin asphalt cement to make a modified asphalt. |
