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F-1500 Turbine Flow Meter Manual 02/18 - 1018-6 / 35726
Page 9
1.3 HOW THE ONICON INSERTION TURBINE MASS FLOW METER OPERATES
ONICON F-1500 Series Insertion Turbine Mass Flow Meters are designed to monitor mass flow
rate by directly measuring fluid velocity, temperature and when required, pressure. The built-
in flow computer calculates the mass flow rate and volumetric flow rate based on these direct
measurements. The sensing head is built into the insertion turbine meter’s flow body. To measure
fluid velocity, the flow meter incorporates a rotating turbine in the flow stream. The rotation
is converted into an electrical output that is proportional to the fluid velocity. Temperature is
measured using a platinum resistance temperature detector (PRTD). When require, pressure
measurement is achieved using an integral solid state pressure transducer.
1.3.1 Velocity Measurement
Fluid passing through the turbine causes its rotor to spin. The rotor is fabricated from 17-4PH
stainless steel which is slightly magnetic, and is positioned in close proximity to a passive
magnetic pickup coil. As each blade rotates by the pickup coil, a small sinusoidal voltage is
generated. This sinusoidal voltage is then amplified, filtered, and shaped by the measurement
electronics. The frequency of the signal is proportional to the flowing velocity.
Flow Velocity Range
To ensure trouble-free operation, turbine flow meters must be correctly sized so that the flow
velocity range through the meter lies within the measurable velocity range.
The measurable range is defined by the minimum and maximum velocity using the following table.
Gas or Steam
Minimum Velocity
Maximum Velocity
ft/sec
m/sec
ft/sec
m/sec
R40
3.5
1.07
43.0
13.11
R30
4.0
1.22
62.5
19.05
R25
5.0
1.52
80.0
24.38
R20
7.0
2.13
100.0
30.48
R15
8.5
2.59
134.6
41.03
R10
12.0
3.66
205.0
62.48
Table 1. Measurable Range
The pressure drop for F-1500 Series insertion meters is negligible.
1.3.2 Temperature Measurement
This flow meter uses a 1000 ohm platinum resistance temperature detector (PRTD) to measure
fluid temperature.
1.3.3 Pressure Measurement
The F-1500 incorporates a solid-state pressure transducer isolated by a 316 SS diaphragm.
The transducer itself is micro-machined silicon, fabricated using integrated circuit processing
technology. A nine-point pressure/temperature calibration is performed on every sensor.
Digital compensation allows these transducers to operate within a 0.3% of full scale accuracy
band within the entire ambient temperature range of -40° F to 140° F (-40° C to 60° C).
Thermal isolation of the pressure transducer ensures the same accuracy across the allowable
process fluid temperature range of -200° F to 750° F (-128° C to 400° C).