Working pressure means the settled pressure of a compressed gas at a reference temperature of 15 °C in a full pressure receptacle;
Operating pressure means the pressure at which the parts of an irrigation system are designed by the manufacturer to operate.
Reid vapor pressure means the vapor pressure of crude oil or other volatile petroleum products at 100 degrees Fahrenheit as determined by the latest edition of ASTM D6377 (RVPE): Standard Test Method for Determination of Vapor Pressure of Crude Oil.
Diatomaceous earth filtration means a process resulting in substantial particulate removal in which a precoat cake of diatomaceous earth filter media is deposited on a support membrane (septum), and while the water is filtered by passing through the cake on the septum, additional filter media known as body feed is continuously added to the feed water to maintain the permeability of the filter cake.
True vapor pressure means the equilibrium partial pressure exerted by a petroleum liquid as determined in accordance with methods described in American Petroleum Institute (API) Bulletin 2517, Evaporation Loss from External Floating Roof Tanks, 1980. The API procedure may not be applicable to some high viscosity or high pour crudes. Available estimates of true vapor pressure may be used in special cases such as these.