An evaporation pan in which the evaporation is measured from water in a pan floating in a larger body of water.


Related Terms

GAGE VALVE

A valve attached to a water column or drum for checking water level.

WATER COLUMN

A vertical tubular member connected at its top and bottom to the steam and water space respectively to a boiler, to which the water gage, gage valves, high and low water alarms and fuel cutoff may be connected.

TRY VALVES

Test valves on a water column used to verify the water level when the gauge glass is out of service.

TRY VALVE

One of three valves mounted on a boiler or water column within the visible range of the gauge glass and used to check the water level.

SOUNDING PIPE

A pipe leading to the bottom of an oil or water tank, for guiding a sounding tape or jointed rod when measuring the depth of liquid in the tank.
Sounding pipes in the engine room are normally fitted with deadweight cocks and screw caps. Caps and cocks should be closed at all times, except when sounding tanks.

SHALLOW WATER EFFECT

The effect that due to the depth of water, the speed of the vessel and shape of the vessel's hull causes the vessel to sink deeper in the water especially in shallow water and at high speed. The vessel becomes sluggish in responding to the rudder.

PNEUMATIC CAISSON

A caisson having a chamber filled with compressed air at a pressure equal to the pressure of the water outside.

PHOTOTUBE CURRENT METER

A device for measuring the speed of water currents in which a perforated disk, which rotates with the current by means of a propeller, is placed in the path of a beam of light that is then reflected from a mirror onto a phototube.

PHLEGER CORER

A device for obtaining ocean bottom cores up to about 4 feet (1.2 meters) in length; consists of an upper tube, main body weight, and tailfin assembly with a check valve that prevents the flow of water into the upper section and a consequent washing out of the core sample while hoisting the corer.

PERMISSIBLE VELOCITY

The highest velocity at which water is permitted to pass through a structure or conduit without excessive damage.

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