Boiler glossary O

OHM -- The SI unit of electrical resistance, such that 1 ampere through it produces a potential difference across it of 1 volt. Symbol OMNIBUS-BAR -- The original term from which the commonly used expression bus-bar is derived. ONCE-THROUGH BOILER -- A monotube boiler in which the feed water evaporates to steam immediately in the tube. Also referred to as Flash Boiler. OPPOSED-CYLINDER ENGINE -- An engine with cylinders, or banks of cylinders, on opposite sides of the crankcase in the same plane, their connection-rods working on a common crankshaft placed between them. ORIFICE -- The opening from the whirling chamber of a mechanical atomizer or the mixing chamber of a steam atomizer through which the liquid fuel is discharged. ORIFICE GAUGE -- A flow gauge consisting of a thin orifice plate clamped between pipe flanges, with pressure take-offs drilled into the adjacent pipes, or of a thick orifice plate similarly, clamped but containing its own pressure take-offs. OSMOSIS -- Diffusion of a solvent through a semipermeable membrane into a more concentrated solution, tending to equalize the concentrations on both sides of the membrane. OSMOTIC PRESSURE -- The pressure exerted by a dissolved substance in virtue of the motion of its molecules. It may be measured by the pressure that must be applied to a solution in order just to prevent osmosis into the solution.

© 2007 Lars Josefsson   Boilers