What is a K Factor?
The axial design PRECISION TURBINE FLOWMETER is inherently linear within
a known turndown range, typically 15:1, based on velocity of the measured fluid. The
device has unmatched capability of precise and repeatable K-Factor generation based on the
turning of the balanced rotor and the subsequently generated frequency pulse signal via
the magnetic coil assembly, providing accuracy of +/-.15% with special calibration
applied. Each pulse generated represents a discrete amount of volumetric throughput.
Dividing the total number of pulses generated by the specific amount of liquid product
that passed through the PTF determines the K-Factor.
Put in the simplest of terms, K-Factor is no more complicated than
understanding that the meter will generate a specific number of pulses for every unit of
product passing through it. If the user can detect the pulses, then it is a
straightforward task to determine flow rate and totals. The K-Factor, expressed in pulses
per unit volume, may be used to electronically provide an indication of volumetric
throughput directly in engineering units.
Mass flow can be accomplished by the addition of pressure and
temperature sensors that are factored electronically. The electronic device continuously
divides the incoming pulses by the K-Factor, or multiplies them with the inverse of the
K-Factor, to provide factored totalization, rate indication, and various outputs. The
frequency of the pulse output, or number of pulses per unit time, is directly proportional
to the rotational rate of the turbine rotor. Therefore, this frequency of the pulse output
is proportional to the rate of the flow.
By dividing the pulse rate by the K-Factor, the volumetric throughput
per unit time of the rate of flow can be determined. Standard electronic devices are
commonly used to provide instantaneous totalization and flow rate indication. Plotting the
electrical signal output versus flow rate provides the characteristics profile or
calibration curves for the PTF.
Although the concept of K-Factor is applied widely with other types of
meters, it should be noted that this value is calculated from analog values in other
meters where a magnetic coil assembly reading a turning rotor is not used. This
calculation has built-in error factors based on a relatively imprecise primary input
coupled with conversions from analog frequency and sometimes back to analog for