Core Factors for Radar Level Gauge Selection
Correctly selecting a radar level gauge requires comprehensive consideration of container volume, shape and operating conditions. Medium characteristics such as corrosiveness, foam and steam directly affect measurement performance and must be evaluated one by one during selection.
I. Impact of Container Conditions on Radar Selection
1. Open Containers
In open water pools, water tanks or natural water bodies, radar level gauge selection is not restricted. Guided wave radar, low-frequency horn radar and high-frequency horn radar can all be used.
2. Closed Containers
Closed containers require consideration of installation nozzle dimensions and internal operating conditions. The minimum installation dimension requirements for different radar types are as follows:
| Radar Type | Minimum Nozzle Size | Minimum Flange Size with Agitation/Foam/Steam/Vacuum |
|---|---|---|
| Guided Wave Radar Level Gauge | DN40 | — |
| Low-Frequency Horn Radar | DN50 | DN150 |
| High-Frequency Horn Radar | DN50 | DN100 |
Note: If agitation, foam, steam or vacuum exists, the flange size must be increased to ensure measurement stability.
II. Selection Strategy for Corrosive Liquids
Corrosive liquids have different requirements for the wetted materials of radar level gauges. The default material is 304 stainless steel and can be upgraded according to the degree of corrosion.
1. Guided Wave Radar Level Gauge
- Generally corrosive liquids: choose 316 material.
- Highly corrosive liquids (such as hydrochloric acid, nitric acid): choose PTFE-lined.
2. Horn Radar (Low-Frequency/High-Frequency)
- Generally corrosive liquids: choose 316 material.
- Highly corrosive liquids: use PTFE coating.
3. Recommended for Highly Corrosive Environments
For highly corrosive liquids such as hydrochloric acid and nitric acid, low-frequency rod radar or high-frequency rod radar is more recommended, as they are designed specifically for highly corrosive environments. However, note that low-frequency rod radar has a large blind zone (0.5-0.7 meters) and is not suitable for small tanks.
III. Key Points for Selection under Foam Conditions
The thickness of foam on the liquid surface directly affects the penetration capability of radar waves. When foam does not exceed 2 cm, the impact is small; when it exceeds 2 cm, the foam thickness and size must be evaluated.
- Fine foam is more difficult to penetrate than large foam.
- The thicker the foam, the greater the difficulty of penetration.
- Low-frequency horn radar is more suitable than high-frequency horn radar.
- For non-adhesive foam, guided wave radar level gauge can be selected, as it can easily penetrate and measure the true liquid level.
IV. Selection Recommendations for Steam Environments
Steam environments have little impact on guided wave radar. They have the least impact on low-frequency horn radar and a greater impact on high-frequency horn radar. During selection, priority should be given to guided wave radar or low-frequency horn radar.
