In the actual measurement process, the common factors that affect the measurement mainly include the following three aspects:
Common factors 1, blind spots
The blind zone is the limit value of the ultrasonic level gauge to measure the liquid level, so the highest liquid level should not be higher than the blind zone. The size of the measuring blind zone is related to the measuring distance of the ultrasonic. Generally, if the range is small, the blind zone is small; if the range is large, the blind zone is large.
Common factors 2, pressure and temperature
Ultrasonic level gauges usually cannot be installed in tank with pressure, because the pressure will affect the level measurement . In addition, there is also a certain relationship between pressure and temperature: T=KP (K is a constant). The change of pressure will affect the change of temperature, which in turn affects the change of sound velocity.
In order to compensate for temperature changes, ultrasonic level gauge probe is specially equipped with a temperature sensor to automatically compensate for the influence of temperature. When the probe sends a reflection signal to the processor, it also sends a temperature signal to the microprocessor, and the processor will automatically compensate for the effect of temperature changes on the liquid level measurement. If the ultrasonic level gauge is installed outdoors, because the outdoor temperature changes greatly, it is recommended to install a sunshade and other measures to reduce the influence of temperature factors on the measurement of the instrument.
Common factors 3, water vapor, mist
Because water vapor is light, it will rise and float to the top of the tank, forming a vapor layer that absorbs and scatters ultrasonic pulses, and the water droplets attached to the probe of the ultrasonic level gauge easily refract the ultrasonic waves emitted by the probe, causing emission The difference between the time and the received time is incorrect, which eventually leads to inaccurate calculation of the liquid level. Therefore, if the measured liquid medium is prone to produce water vapor or mist, ultrasonic level gauges are not suitable for measurement. If the ultrasonic level gauge is indispensable, a waveguide apply lubricant on the surface of the probe, or install the ultrasonic level gauge obliquely so that the water droplets cannot be caught, thereby reducing the impact of the water droplets on the measurement. influences.