Compressors that operate with an intake pressure below
atmospheric and discharge pressure usually atmospheric or slightly
higher.
Valves
Devices with passages for directing flow into alternate paths.
Vane compressor
Is a single shaft, positive displacement rotary compressor.
Vane material
Most common material is phenolic resin-impregnated laminated
fabrics, such as asbestos or cotton cloth. For oil free service,
bronze and carbon/graphite vanes are used.
Vapor
Fine separated particles floating in the air and clouding it.
A substance in the gaseous state.
Vapor pressure
Is the pressure exerted by a vapor confined within a given
space. The vapor may be the sole occupant of the space, or may be
associated with other gases.
Varnish
The oxidation of conventional hydrocarbon lubricants when they
reach the end of their useful life and begin to breakdown. Can
cause operating temperature increase, increase brake horsepower
and plugs separator, can destroy air end.
V belt drive
A drive arrangement for power transmission to compressors.
Venturi
A tube with a narrow throat (a constriction) that increases the velocity and
lowers the pressure of the liquid passing through it, creating a partial vacuum immediately after the constriction in the tube. The vacuum created has a sucking
effect, and a venturi is commonly used to introduce a liquid (such as
a regenerant) or gas (such as air) into a flowing water stream.
Viscosity
Is a measure of resistance to deformation, or reluctance to be
squeezed out a bearing. Indicates the internal friction of a
fluid. Viscosity in normal lubricants is reduced as temperature
increases
Viscosity index (VI)
Is a measure of the rate of change of viscosity with
temperature. Oils with high VI have low viscosity changes.
Volumetric
efficiency
The ratio and percent of the actual delivered capacity
(measured at inlet temperature, pressure and gas composition) to
the piston displacement.
Volute
A stationary, spirally shaped passage that converts velocity
head to pressure.
Voting alarm
(Compressors/Gas Turbines) Is an alarm system that has maybe 3
sensors connected to it and it will require minimum of 2 of the 3
to alarm before the alarm will act. There is a controller
connected that does the logic decision based on set parameters.
