Knowing the certain basics procedures, practices, and precautions apply to the flow instruments makes it easier for us to offer solutions to our customers. If we examine briefly the measurement methods of our products used in measurement, common devices for flow measurement fall into the following categories:
a. Differential-Head Meters:
It is one of a flow measurement technique in which diffrential meters measure flow inferentially from the differential pressure caused by flow through a primary elements. Flow is proportiona to the square root of the differential pressure produced between the tappings at calculated high and low pressure points. This differential is sensed by our diffrential pressure transmitters.
b. Variable-area Meters / Rotameters
This techniques works on the principle that a float within a vertical tapered tube will assume a position that is a function of the flow rate through the tube from the bottom. In this type of method, the choseen float shall have higher density than the measured fluid. The annular area through which the flow must pass is the difference between the internal area of the taper tube at the point of balance and the area of the float head. Due to increasing constantly the internal area of and being continuously variable from bottom to top, whereas the float head area remains constant, the term variable area is used to describe this type of meter. At a constant differential pressure, flow is directly proportional to area.
c. Magnetic Meters
The unobstructed flow meter measure the volumetric flow rate of any liquid that has the required electrical conductivity. Faraday's law of elctromagnetic induction principle is used for determining rate.
d. Vortex / Swirl Meters
Creating an obstruction in the flowing stream generates a vortex train of high and low pressure areas.
e. Special Meters (Coriolis & Thermal)
These meters often used for special applications. The manufacturing of these devices needs specific consultncy applications.
Our Transmission Practice:
Standart industry practice is to convert the flow measurement to a pneumatic or electrical signal and transmit the signal to remote receiving instruments. Sometimes it is standard practice to transmit the flow measurement in local installations where long piping. Otherwise other methods could need to be required.To illustrate, the cases where solids present in the process fluid can result plugging or in which differences in elevation can result in head problems.
Due to vibration in process, most instruments are susceptible to damage, abnormal wear, or malfunction. If any part of the flow system or equipment is subject to vibration, the affected instruments should be provided with vibration-free supports.
When the flow pulsates, it is difficult to measure. Head-type flowmeters and instruments with mechanical movements, such as postive-displacement meters ad turbines, should not be used in pulsating flow applications except from some application where fast responce diffrencial pressure transmitters to be used.
Purging and Sealing:
When viscous liquids and corrosive process fluids measuring, or the possiblity of plugging where solids or sluries exist, sensing lines to the sensing head of the differential transmitter should be protected by means of a diaphragm seal or purged impulse lines. The diaphragm seal unit should have wetted parts suitable for the fluid measured, and the materials should be corrosion resistant.
Another importand issue in process measurement instrumentation is piping. The furnishment and installation of process connections to the instruments should follow applicable piping and material specifications. Before assembly, all pipe and connections shall be well deburred after cutting and blown clean of cttings and other foreign materials. Also alternative to pipe, tubing of suitable material may be used.
In the recent decades, the market for the products of the industrial process industries
has changed greatly. The manufacture of mass products has shifted to locations where
raw materials are available economically. Competitive pressures have forced a swing
to specialization as well as to an ability to adapt to customers desires. The systems are
designed so that the economic data, such as raw material properties, raw material
costs, batch sizes, are quickly integrated into the processes. An important consideration
is the assurance and improvement of product quality.
The operation of such systems requires a high degree of automation. With the assistance of process technology the control of the procedures can be optimized and personnel requirements minimized. The process control technology assures that process cycles are documented so that the quality of the product is always traceable.
The most important prerequisite for automation is knowledge of the actual process parameters,
which can be ascertained utilizing measurement instruments. If the actions
dependent on the measurements are to be realized then the specifications must naturally
be qualitatively high. Therefore, the measurement instrument requires:
• high accuracy
• easily understandable functionality
• easy operation and maintenance
• testability even without a test bench
• self monitoring
• error signalling / self-diagnostics
• communication ability
The planner of an industrial process system assumes in advance that the measurement
error limits will be satisfied. However, it is not always possible to divorce oneself
from the problems associated with the measuring point.
This publication for industrial flow measurement aims at supporting practitioners in
solving their versatile and demanding tasks. At the same time, it is intended to provide
a vivid overview of the basic measuring principles and their limitations to interested
Getting the best levels of efficiency and performance from your
production process requires reliable, accurate flow measurement.
Choosing ENDUS flow measurement solutions for your application
means to decide for high-quality measurement. We offer one of
the world’s largest and most innovative product ranges, unrivalled
in its breadth and scope.