A little competition between two rival entities always spices things up. This is true even in the level measurement world where two most commonly used methods, the Ultrasonic level measurement and the Radar level measurement compete for supremacy. The ultrasonic technique uses sound-based measurements while the radar technique use high frequency electromagnetic waves. Below are some of the glaring differences between the two, both functionally and by design.
1. Uses sound waves:
The sound waves must travel through a medium such as air which means the transmitters are unsuitable for use in a vacuum. The sound signals require air molecules to be transmitted and the absence of these will mean the sound will not be propagated.
2. Surface factors:
The sound waves are affected by surface condition such as foam and other forms of debris which may end up affecting the returning sound signals. This has an effect on the measurement accuracy.
3. Reflection and angles of incidents:
The sound waves must be reflected in a straight line which means the reflective surface must be flat. If it is a liquid, the liquid surface must be non-turbulent or undisturbed.
4. The operating temperature:
The operating temperature for the sound waves must not exceed 60 degrees Celsius. In addition to that, the temperature environment should be constant to avoid inconsistencies in measurement.
5. Operating pressure:
Devices that use ultrasonic technology should not be subjected to extreme pressure limits. Most of these devices have a maximum pressure of 30psig.
6. Affected by environmental conditions:
Sound waves are affected by environmental factors such as the amount of vapor, the humidity and other contaminants. These may affect the accuracy of the return signal which consequently affects the accuracy of the measurement.
7. Non-contact measurement:
Ultrasonic sound signals do not require a contact to travel to the surface interface and back. They can be transmitted through other mediums such as air.
The performance of this technique is based on the strength of the reflected signals which are affected by the process conditions.
Ultrasonic measurement technique is relatively cheaper as compared to the Radar technique because of its low precision and accuracy.
10. Smaller measurement range:
Ultrasonic signals have a smaller measurement range hence a smaller scope in applications.
Guided Wave Radar
1. Uses electromagnetic waves:
Guided Wave Radar (GWR) uses electromagnetic waves to determine the surface level of fluids. The EM waves travel through a probe to the surface of the fluid and are reflected back while some of the waves proceed to the base of the container.
2. Unstable Process Conditions:
Changes in the density, acidity or viscosity of the fluid does not affect the accuracy of the measurements.
3. Turbulent surfaces:
GWR does not depend on the angle of the fluid to measure the surface level. In fact, this technique can be sued to measure recirculating fluids or even fluids with a propeller mixer.
4. Sticky fluids & Fine powder:
GWR works with all fluids and powders including highly viscous fluids such as latex, fat, paint, titanium and others.
5. High temperature:
GWR can perform under very high temperature environments unlike the ultrasonic technique whose performance is limited by extreme temperatures. GWR performs well in temperatures of up to 31 degrees.
6. High pressure:
GWR technique is not affected by conditions with extremely high pressure. It can perform well even in maximum pressure of up to 580 psig.
7. Contact measurement:
The GWR radar signals require a contact such as a probe to travel to the surface interface and back to the sensors.
The performance of the GWR radar signals is not dependent on the process conditions. The signals strength will be maintained regardless of the conditions.
GWR has a higher cost in terms of acquisition and maintenance due to the excellent performance and precision of the measurement obtained.
10. Large measurement range:
GWR has a wider measurement range and therefore has a larger scope as far as its application in various fields is concerned.
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