Endress+Hauser Proline Promass 80E, Техническая информация

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Proline Promass 80E, 83E
Hauser 3
Function and system design
Measuring principle The measuring principle is based on the controlled generation of Coriolis forces. These forces are
always present when both translational and rotational movements are superimposed.
F
C
= 2 ·  m (v ·  )
F
C
= Coriolis force

m = moving mass
 = rotational velocity
v = velocity of the moving mass in rotating or oscillating system
The amplitude of the Coriolis force depends on the moving mass

m, its velocity v in the system, and
thus on the mass flow. Instead of a constant angular velocity  , the Promass sensor uses oscillation.
In the sensor, two parallel measuring tubes containing flowing fluid oscillate in antiphase, acting like
a tuning fork. The Coriolis forces produced at the measuring tubes cause a phase shift in the tube
oscillations (see illustration):
• At zero flow, in other words when the fluid is at a standstill, the two tubes oscillate in phase (1).
• Mass flow causes deceleration of the oscillation at the inlet of the tubes (2) and acceleration at the
outlet (3).
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The phase difference (A-B) increases with increasing mass flow. Electrodynamic sensors register the
tube oscillations at the inlet and outlet.
System balance is ensured by the antiphase oscillation of the two measuring tubes. The measuring
principle operates independently of temperature, pressure, viscosity, conductivity and flow profile.
Volume measurement
The measuring tubes are continuously excited at their resonance frequency. A change in the mass and
thus the density of the oscillating system (comprising measuring tubes and fluid) results in a
corresponding, automatic adjustment in the oscillation frequency. Resonance frequency is thus a
function of fluid density. The density value obtained in this way can be used in conjunction with the
measured mass flow to calculate the volume flow.
The temperature of the measuring tubes is also determined in order to calculate the compensation
factor due to temperature effects.
1 2 3
A
B
A
B
A
B