1、真空环境和传播介质变化（如强挥发性）的场合
1. Occasions when the vacuum environment and transmission medium change (such as strong volatility)
超声波本质是一种机械波，需要借助介质来传播，所以，超声波液位计最大的应用局限是不能用于真空环境和传播介质变化（如强挥发性）的场合。
The essence of ultrasonic wave is a kind of mechanical wave, which needs to be propagated by medium. Therefore, the biggest application limitation of ultrasonic liquid level meter is that it can not be used in the vacuum environment and the situation where the medium changes (such as strong volatility).
2、大量程和高精度的场合
2. Large range and high precision occasions
作为一种机械波，超声波在传播的过程中会存在衰减，考虑到精度和量程的矛盾性，超声波液位计实际应用中量程范围较小，精度稍差，所以在大量程和高精度的场合不能使用超声波液位计。
As a kind of mechanical wave, ultrasonic wave will be attenuated in the process of propagation. Considering the contradiction between accuracy and measuring range, the range of ultrasonic liquid level gauge is small in practical application, and the accuracy is slightly poor, so ultrasonic liquid level gauge cannot be used in large range and high precision occasions.
3、高温高压场合
3. High temperature and high pressure
超声波液位计的换能器由压电陶瓷和塑性外壳灌封而成，所以在高温高压环境下不能使用，一般来说，超声波液位计的最大耐受温度为80℃。
The transducer of ultrasonic level gauge is made of piezoelectric ceramic and plastic shell, so it can not be used in high temperature and high pressure environment. Generally speaking, the maximum withstand temperature of ultrasonic level gauge is 80 ℃.
4、温度频繁变化的场合
4. Frequent temperature changes
超声波液位计在实际应用中测量的时间量，结合声速，可以得出距离值（时间×声速=距离）。但是声速会随着介质和温度的变化而变化，所以超声波液位计也不能应用于温度频繁变化的场合。
The distance value (time × sound speed = distance) can be obtained from the time measured by ultrasonic liquid level meter in practical application combined with sound speed. But the speed of sound will change with the change of medium and temperature, so ultrasonic liquid level meter can not be used in the situation of frequent change of temperature.