Non contact level measurement refers to that level sensor and level sensor don't contact fluid directly by certain technologies. This feature provides many kinds of advantages, e.g. no moving parts, no liquid contacting, no pollution to fluid, smaller size body, longer life, lower cost for certain application, suitable for acid and alkali and corrosive fluid(part of models), no cutting and no opening (part of model),etc.
2 kinds of Working Ways: Non-Contact and Clamp On
No contact level measurement includes two kinds of different working ways and we can call them non contact and clamp on. Of course, such calling is not definition, but just for reference.
1). Non-contact working in air environment, and typical technologies have ultrasonic level sensor and radar level transmitter. This working way usually requires vertical installing way on top of container(radar level also supports side mounting for several application), and when used for closed container, it requires to cut a hole to install related level probe. This way is mainly used higher level test, e.g. 1 meter and above. This is usually for continuous level measurement.
2).Clamp on working way from external surface, and typical have capacitance level, ultrasonic level and optical fiber level. This way can be used for open and closed container. Level probe is installed on external surface of various containers, e.g. tank, bottle, drum, etc. It requires to make level probe to contact container surface closely without any gap space. This way is completely isolated from inner liquid and provide unique solution for many projects. It usually requires side mounted and mainly used for point level monitoring.
There are 5 types of non contact level sensors as often used solutions. Here we will introduce them to make more understanding.
1. Capacitive Non Contact Level Sensor Switch-Clamp On Way
Capacitive non contact water level sensor or non contact level switch has a very low cost and small size body. The level sensors are very suitable for large quantity application with lower cost. It can be used for non-metal containers, e.g. plastic, glass, porcelain, etc. One of its main deciding factor is container wall thickness. Take plastic container as example, there are mainly 3 kinds of thickness range: 3mm, 10mm and over 10mm. For more information, please visit our non contact water level sensor.
2.Infrared Level Sensor Switch-Not Contact, Not Clamp On
Infrared level sensors also have lower price, but its size is bigger. It utilizes infrared function of photoelectricity distance measurement. Its effective sensing distance can reach 80mm. Its working way can be imaged like flashlight. Our infrared level sensors have sending/receiving integrated together. When power sensor on, its infrared light is produced to detect solid or liquid level, then reflected back to receiving unit. By this, infrared level sensor switch can monitor level. It doesn't require to be installed on container surface closely. But it may be easily influenced by sun light, meanwhile, it requires bigger installing space. The infrared sensors are also used for other industries, e.g. product counter, goods positioning, solid level test, etc.
3.Optical Fiber Level Sensor
Optical fiber level sensors have 2 kinds of combination ways.
One is use 2 pieces of optical fiber probes and make them beam detector. When level reach beam level, there is a signal, when level is down, there is another different signal.
The other is integrated with sender and receiver. It has compact structure and usually used for tube level/flow checking.
4.Ultrasonic Level Sensor and Transmitter
Ultrasonic level sensor and transmitter also have 2 kinds of working ways, non-contact way and clamp-on way.
When use as non-contact way, it is often used for tank or open place, e.g open channel, pool, small river, etc. For closed tank or other containers, it requires to but hole on top of containers so that ultrasonic level sensors can be inserted to detect level. Such application is usually used for higher level measurement, e.g. at least 1 meter or higher.
The other is clamp on way which requires ultrasonic level sensors to be installed on side or bottom of containers. Such technology utilizes ultrasound sonar echo principle which is different from non contact ultrasonic level above. Side mounting is used as level switch for point level, and bottom installing is used for continuous level measurement. For such type, its price may vary sharply.
5.Radar Level Transmitter
Radar technology is firstly used for army and then gradually transferred to common using. Radar wave belongs to electromagnetic wave which is more stable than ultrasound wave. Thus, radar level is more stable than ultrasonic level. Ultrasonic level are often used for liquid under common condition, but radar level is often used in harsh application. Radar level is often used for solid level measurement and when used for liquid, it is usually used for oil tank or big river, etc. But radar level always have a higher cost and many common projects can't afford it.
Each type non contact level sensor has its using and no one can meet all of applications, and user should select proper type as the detailed condition. But usually capacitive level and ultrasonic level should be first 2 considerations while select non contact liquid level sensors.