一、先问清四个问题
- 介质是什么？是否有腐蚀性、是否粘稠、是否易结晶？
- 液面是否有泡沫、蒸汽、粉尘或剧烈波动？
- 温度与压力范围？是否有爆炸性环境？
- 精度要求、量程与安装位置（是否有盲区空间）？
二、超声波液位计
原理：探头发射超声波，测量回波时间换算距离，属于非接触测量。
- 优点：非接触、安装简单、价格适中、维护量小。
- 局限：受泡沫、蒸汽、粉尘、液面剧烈波动影响；存在盲区，量程需扣除盲区；真空或高压工况受限；温度梯度大时声速变化会影响精度。
- 适用：清水池、污水池、水箱、明渠（配合堰槽）等常温常压清洁工况。
三、雷达液位计
原理：发射微波并接收液面回波，常见 26 GHz 与 80 GHz 频段，频率越高波束角越小。
- 优点：不受蒸汽、泡沫、粉尘与真空影响，精度高，可用于高温高压。
- 局限：成本较高；介电常数极低的介质回波弱；安装位置需避开搅拌器与进料冲击区。
- 适用：蒸汽或泡沫严重的工况、高温高压容器、精度要求高的场合、以及需要小盲区的场合。
四、静压式（投入式）
原理：测量液体静压换算液位，公式为液柱高度与介质密度的乘积。
- 优点：结构简单、成本低、安装方便。
- 局限：精度受介质密度变化影响；探头易结垢或被淤泥覆盖；需与大气相通（表压型）。
- 适用：深井、水箱、密度稳定的清水。
五、其他常见方式
- 磁翻板液位计：就地直观显示，可配远传，适合需要现场目视的场合。
- 浮球 / 浮筒：结构简单，多用于开关量报警或简单控制。
- 电容式 / 射频导纳：适合粘稠、易挂料的介质。
- 音叉 / 振棒开关：用于高低位开关量报警，防止溢流或干转。
六、安装要点
- 避开进料口、搅拌器与出料口，避免回波干扰；
- 超声波与雷达需保证波束范围内无障碍物；
- 留出盲区距离，量程不能顶格使用；
- 户外安装加遮阳罩，避免阳光直射与雨水侵入；
- 爆炸性环境按要求选防爆型式并可靠接地。
把介质、量程、温度压力、是否有泡沫蒸汽、安装条件告诉我们，我们可以帮您匹配测量方式与安装附件。
1. Four questions first
- What is the medium - corrosive, viscous, prone to crystallising?
- Is there foam, steam, dust or heavy surface agitation?
- What are the temperature and pressure ranges; is the area hazardous?
- What accuracy, range and mounting position are available (is there space for the blanking distance)?
2. Ultrasonic level transmitters
They emit an ultrasonic pulse and convert the echo time into distance - a non-contact method.
- Advantages: non-contact, simple to install, moderate price, low maintenance.
- Limitations: affected by foam, steam, dust and heavy surface agitation; a blanking zone reduces usable range; limited in vacuum or high pressure; large temperature gradients change the speed of sound.
- Suits: clean water basins, sewage tanks, water tanks and open channels (with flumes or weirs) at ambient temperature and pressure.
3. Radar level transmitters
They emit microwaves and receive the echo from the surface; 26 GHz and 80 GHz bands are common, and higher frequency gives a narrower beam.
- Advantages: unaffected by steam, foam, dust or vacuum, high accuracy, usable at high temperature and pressure.
- Limitations: higher cost; media with very low dielectric constant give weak echoes; mounting must avoid agitators and the feed impact zone.
- Suits: heavy steam or foam, high-temperature and high-pressure vessels, high-accuracy duties and applications with limited blanking distance.
4. Hydrostatic (submersible)
Level is derived from hydrostatic pressure, which is the product of liquid column height and medium density.
- Advantages: simple, low cost, easy to install.
- Limitations: accuracy suffers when density varies; the probe fouls or gets buried in silt; gauge-pressure types need venting to atmosphere.
- Suits: deep wells, water tanks and clean water of stable density.
5. Other common methods
- Magnetic level gauges: clear local indication, optional remote output, good where operators need to see the level.
- Float / displacer: simple, mostly for level alarms or simple control.
- Capacitance / RF admittance: for viscous or coating media.
- Tuning fork / vibrating rod switches: high and low level alarms to prevent overflow or dry running.
6. Installation points
- Keep away from inlets, agitators and outlets to avoid echo interference.
- Keep the beam path of ultrasonic and radar clear of obstructions.
- Allow for the blanking distance; never use the full range.
- Outdoors, fit a sun shield against direct sunlight and rain ingress.
- In hazardous areas, select the required protection type and earth reliably.
Tell us the medium, range, temperature and pressure, whether foam or steam is present and the installation conditions, and we will match the method and mounting accessories.