Advantages:
- The principle of universal application to measure flows of liquids and gases.
- Direct measurement of mass flow (no pressure and temperature compensation).
- The principle of measurement is not dependent on the density and viscosity of the fluid.
- The measuring accuracy is very high (typically ± 0.1% vL).
- The multivariable sensor, measuring both the mass flow, density and temperature.
- It is insensitive to changes in the velocity profile.
- Does not require input and output sections.
Disadvantages:
- The initial financial investment is relatively high.
- The cost of installation can be considerable, depending on model and manufacturer.
- The temperature range is limited: typically -50 to +350 ° C (-60 to +660 ° F).
- Its use is restricted to fluids with low content of gases and fluids in a single phase.
- Some large models are very heavy.
Measurement systems double tube
In most double-tube flow meters, measuring tubes oscillate counterphase, this provision effectively decoupled maintain the flow of influences due to external vibrations. There are several types of double tube flowmeters. With respect to the geometric characteristics of the measuring tubes, each manufacturer offers different geometries and models can be found straight pipes, curved or slightly arched. The straight or slightly curved tube that uses E + H sensors allow you to build compact and space saving (Figure below):
Ill.: mass flow flowmeters Corioiis effect of E + H (examples).
- Promass F (two left): Standard Sensor versatile, also suitable for large flows.
- Promass A (top right): single tube system for small flow volumes (DN 4, 1 / 24 to 1 / 6 ").
- Promass I (middle): pipe measuring system designed for hygienic applications simple.
- Promass E (center right) measuring system with a property cost in lower relative to the measurement systems "traditional" applications comparable.
- Promass M (lower left): Measuring system for process pressures up to 350 bar (5,000 psi).
Promass-H (n Down, Right ): Single tube system especially for chemically aggressive fluids.
Measurement systems of a single tube
Measurement systems have a single tube several advantages over the double tube:
- They are easy to clean.
- The losses are significantly lower.
- Efforts are induced in the fluid-less because they do not need a bulkhead to divide the flow into two measuring tubes.
The drawback of this design - a single oscillating measuring tube - is that the decoupling characteristic inherent in the double tube flowmeters are not obtained immediately. Therefore, care must be taken during the development stage to provide the flow of features that effectively disengage the system from outside influences.
The system of "torsion balance":
E + H decoupling achieves this by combining high resonant frequency characteristic with its patented torsion balance, Torsion Mode Balanced (TMB). In the case of simple tube sensor Promass I, the balance needed for the system to perform a correct measurement is achieved by means of a pendulum mass eccentrically arranged in the measuring tube, which oscillates in the opposite direction to achieve an effect of torque ( following illustration). Thanks to this integrated system balance, Promass I so easy to install as any dual-tube system. No special mounting vibration upstream inhibitors or comment below the measurement sensor.
The measuring system Promass I can determine the viscosity even "chain" as another parameter of the process.
Figure 83: Inhibition of the vibrations of the system of "torsion balance" of Promass I.
This measurement system simple tube was introduced in 1997 by E + H and does not require any support or accessory added at all.
w = angular speed, m1 = mass of the measuring tube more fluid, m2 = mass pendulum
speed v1 = m1, m2 v2 = velocity, p = Momentum
