Analysis of Common Problems of E+H Ultrasonic Level Gauge
E+H ultrasonic level gauges are widely used in industrial level measurement, but on-site working conditions are complex. Agitation, foam, steam, blind zone, and temperature-pressure variations can all affect measurement performance. This article summarizes common problems and countermeasures for reference by engineering technicians and procurement personnel.
1. Influence of Agitation on Measurement
On-site vessels often have agitators, and large liquid fluctuations lead to unstable echo signals, affecting ultrasonic level gauge measurement.
- Appropriately reduce agitator speed to reduce liquid surface fluctuation.
- Offset the probe from the agitation center to avoid the vortex area.
- Install a standpipe to effectively eliminate the influence of agitation on level measurement.
2. Influence of Foam on Measurement
Foam is a common interference source for ultrasonic level gauges and can be classified into four types by property: dry, wet, neutral, and heavy.
| Foam Type | Influence on Ultrasound | Measurement Feasibility |
|---|---|---|
| Dry foam, wet foam | Can reflect ultrasonic waves back | Basically no influence |
| Neutral foam | Absorbs and diffuses part of the ultrasonic waves, echo is unstable | Large error, or even impossible to measure |
When the medium surface is covered with thick, dense foam, measurement error increases significantly. Under severely interfering working conditions, the E+H ultrasonic level gauge can shield foam interference by installing a standpipe.
3. Influence of Steam and Mist
Under high-temperature environments, liquids easily generate steam or mist. Steam is lighter than air and floats to the tank top, forming a steam layer.
- The steam layer absorbs and scatters ultrasonic pulses.
- Installing a standpipe can reduce or weaken the influence of the steam layer on measurement.
4. Influence of Blind Zone
The blind zone of an ultrasonic level gauge is similar to the area near the human eye that cannot be seen clearly; when an object is too close to the probe, it cannot be accurately detected.
- The blind zone varies with range: a small range means a small blind zone, and a large range means a large blind zone.
- The highest liquid level to be measured must not be higher than the blind zone of the ultrasonic level gauge.
5. Influence of Pressure and Temperature
Ultrasound is essentially a mechanical wave and cannot propagate in a vacuum; as temperature rises, the maximum allowable pressure of the level gauge decreases accordingly.
- Pay attention to temperature correction of the maximum pressure value during model selection.
- For outdoor installation, a sunshade can be added to reduce the influence of temperature factors.
6. Precautions for Standpipe Installation
When installing the conduit (standpipe), pay attention to the following points to ensure stable measurement:
- Select an appropriate conduit diameter.
- The interior of the conduit must be smooth, with no welding seams.
- Open small holes within the blind zone to ensure pressure balance inside and outside the pipe.
- The lower end of the conduit must be immersed below the lowest measured liquid level.
- The lower end of the conduit must have a 45° bevel to maintain normal liquid flow.
Following the above key points can significantly improve the measurement reliability of the E+H ultrasonic level gauge under complex working conditions.