21 JANUARY 2003
STANAG. NATO standardization agreement.
. A low area
or depression that
Thief. Sampling apparatus that gets liquid samples within 13 millimeters (0.5 inch) of the bottom of a
Type I hydrant system. See "Panero system."
Type II hydrant system. See "Pritchard system."
Type III hydrant system. See "Phillips system."
Type IV refueling system. See "Hot pit system."
Unloading header. See "Offloading."
Upper explosive limit (UEL). Sometimes referred to as upper flammable limit. The maximum
concentration of a flammable vapor in the air that will ignite if an ignition source is applied.
Upstream. A term used to describe direction of flow in a pipeline. Upstream is when the flow is
moving toward a component or reference point.
Valve position indicator (VPI). A valve accessory that indicates its position (open or closed).
Vapor lock. Malfunction of a pumping system caused by vaporizing the fuel.
Vapor pressure. Internal pressure of vapor in a liquid, usually in psi; an indication of volatility.
Venturi. A tube of a smoothly shaped construction that creates differential pressure similar to an
orifice plate but much more accurately.
of the internal resistance
of a fluid
Volatility. Measure of the tendency of a liquid to vaporize (vapor pressure).
Voltage. Electrical potential or potential difference.
Volume. The amount of space occupied by a three-dimensional figure as measured in cubic units (e.g.,
inches, feet, quarts, gallons); cubic capacity.
Water draw-off. A valve or similar device used to remove free water from the tank bottom.
Water slug shutoff. Valve in the filter/separator (F/S) discharge piping which closes automatically
when the water in the F/S rises above a set level.
. Loss of the more volatile components
of a product because
Weatherproof. Electrical enclosure used for outdoor service in nonhazardous areas.
Weight. The force with which a body is attracted toward the Earth or a celestial body by gravitation,
and is equal to the product of the mass and the local gravitational acceleration.