From Flow Measurement
|This property is of importance when considering magnetic flowmeters. In most|
designs, the meter is able to detect flow only if the liquid is capable of conducting
electricity to a small extent. Organic liquids such as oils and hydrocarbons are
almost perfect insulators with no significant conductivity. In most cases they cannot
be measured by magnetic meters. The minimum conductivity is always specified
by the manufacturer, and it is very important to be sure the liquid is
sufficiently conductive. A spot check for conductivity sometimes indicates that it
is high enough, but it is quite possible that, at times, the material changes and the
meter can fail to operate.
|When conductivity is borderline, be sure to make a number of tests at different times — not just once or twice.|
The dimensional units for conductivity are usually given as micromhos/cm,
micromhos/cm3, or siemens (S). Surprisingly, all these mean the same thing; they
refer to the conductance between two plates, one cm2 in area and one centimeter
apart, with the liquid in between them.
Sometimes data is presented as “resistivity” rather than “conductivity.” The two
terms are merely reciprocals of each other, and the units of resistivity are...
Products & Services
Topics of Interest
The specific heat of fluids is important when computing heat flow from a mass flow measurement and differential temperature. The equation is: Q = mCp = ΔT (3-11) where: ...
CIP system instrumentation typically serves two purposes. The first, its regulatory function, is to maintain control of the process, so that the appropriate cleaning solutions are delivered at the...
Flow Transmitters Flow is measured by a number of different methods. This section will cover flow measurement made using the following types of flowmeters: Differential Pressure Magnetic...
In a discussion of flow measurement it is important to become familiar with the various physical properties, their nomenclature, and their units of measurement. Depending on the type of flowmeter,...
Turbine Flowmeters Turbine flowmeters are designed to accurately measure the flow of liquids and gases in pipes. They are a volumetric flow-measuring device. The range of flow is from 0.001 gpm to...