How do they affect the measurement of conductive material deposition inside the pipe?
As with any principle of measuring the flow velocity, a reduction of the cross section of the pipe causes errors in the calculation of volume flow. Furthermore, heavy deposition of materials in the sensors can also cause attenuation of the signal.
How does it affect the transit time measurement signal the presence of gas or solid?
The presence of solids and gases attenuates the ultrasound signal. Measurement becomes problematic if the content of solid particles or gases exceeds 1% by volume. From 2% in volume, measured by this method becomes impossible. The fibrous solids, common in sewers and facilities for the manufacture of paper pulp, are particularly difficult. Fine particles of sand type, however, have no such trouble.
What if I do not take into account the input and output sections recommended?
If the velocity profile is not completely well-formed downstream of any attachments, may cause errors whose magnitude depends on the measuring principle and the position sensor. This effect occurs particularly with asymmetric turbulent flow profile is formed after an elbow. For these cases are best multipath measurement systems to the systems of a single path.
How does it affect the measurement a partially full pipe?
In this case we must make special accommodations. The transit time method of signal provides the velocity of flow, but also need to measure the water level.
Does ultrasonic measurement depends on the speed of the fluid?
No. The equipment measuring ultrasonic flow measurement is independent of fluid density.
Does ultrasonic measurement depends on the temperature of the fluid?
A change in temperature of the fluid causes a change in the speed of sound waves. Ultrasonic flowmeters operate on the transit time method of signal eliminates this effect because it is compensated by measuring fluid velocities in the sense of movement and flow in the opposite direction.
What key differences have the transit time method of signal and the method of the Doppler effect?
The transit time method of signal is used for measurements of accuracy with clean fluids. In this method, the content of gas bubbles or solid particles in the fluid must not exceed 1% by volume. In fact, this method does not require the presence of gas bubbles or solid particles in the fluid.
In contrast, the Doppler method is used mainly in measuring flow rates and / or the estimated velocity profile. This method is suitable for fluids with presence of gas or solid particles containing more than 1% by volume. The fluid velocity is determined from the variation in frequency between the transmitted and reflected signal. With such fluid measurement accuracies can be achieved between 3 and 10%.
Where ultrasonic sensors are used external fixation?
External fixation systems are suitable for a wide variety of industries for applications such as:
- For installation of a flowmeter in a pipeline without interrupting service.
- For monitoring, measuring several pipelines.
- In applications with highly corrosive fluids.
Before using a team of external fixation is necessary to know the following parameters to prevent the error is greater than necessary:
- The thickness of the pipe wall
- The manufacturing material of the pipe
- The coating material of the pipe and its thickness
- The speed of sound in the fluid (or alternatively, the temperature and type of fluid)
How important is a good positioning of the ultrasonic sensors?
The exact position of the two ultrasonic sensors can be calculated from the parameters mentioned in the previous question. A vague assembly factor affecting calibration and sensitivity to the presence of solid particles in the fluid. The sensors are typically mounted installation rails, brackets, etc.., Special.
What nominal diameters can be used external fixation devices?
The nominal diameter smaller than allow the installation of an external fixation in the state of the art is from DN 20 (3 / 4 ").
What is the influence of the velocity profile in the measurement?
A well-defined velocity profile is very important because ultrasonic flowmeters normally register the fluid velocity along a single straight line, ie along the acoustic path of the beam. Some measurement systems employ two or more acoustic paths to reduce or compensate for this effect (Fig. below).
Ill.: Ultrasonic measurement systems simple acoustic path (a) and double (b)
How does the thickness of the coating to the execution of the sensors of external fixation?
Thick coatings attenuate ultrasound signals. We must bear in mind the type of coating and its thickness.
Do the ultrasonic sensors are sensitive to sounds coming from the structure or fluid?
The sounds generated by the pumps or valves are substantially lower frequency, so it is easy to distinguish the signal from spurious noise ultrasound.
Is it dangerous prolonged exposure to ultrasound people?
Waves from an ultrasonic transmitter is transmitted more easily within a liquid in the air and thus flow through the fluid rather than outward. In addition, pingers are often contained within a steel head that blocks the transmission of sound to the outside. Therefore, the intensity of the sound waves that escape into the air is very low and poses no health risk.
Fig: Installation and positioning of ultrasonic sensors with external fixing mounting rails. No need to interrupt service.
