The axial design PRECISION TURBINE FLOWMETER (PTF) 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 transmission purposes.
Check Calculations using K-factor -