How do different types of liquid level measuring devices work?

This article provides an overview of the operating principles of universal level measurement equipment, covering the following: DOWESTON'sRadar level transmitter, Guidance Radar Transmitter, ultrasonic level transmitter, and finallyCapacitive Level Transmitter. 

Radar level transmitter

How does a radar level transmitter work?

Radar level transmitters operate using high-frequency radar pulses that are emitted by an antenna and reflected from the product surface. The flight time of a reflected radar pulse is proportional to the distance traveled. If the tank geometry is known, the level can be calculated from this variable.

Advantages of radar level transmitters

Very accurate - ±0.5mm (0.02in)

Top installation

Contactless

Accuracy is not affected by dielectric constant, density and conductivity

No need to reset when changing fluids

Things to consider:

Tank design must be considered

Bubbles can be a problem

Blocking distance

Turbulent surface

Minimum dielectric constant

Request Manual 

Guidance Radar Level Transmitter

How does a pilot radar level transmitter work?

Guidance radar level transmitter with along probe guidanceHigh frequency radarPulses work together. When a pulse strikes the surface of a medium, the characteristic impedance changes and a portion of the transmitted pulse is reflected. The instrument measures and analyzes the time between pulse emission and reception and directly measures the distance between the process connection and the product surface.

Advantages of Guidance Radar Level Transmitter

Very accurate - ±0.2mm (0.04in)

Works with some foam

Top installation

Accuracy is not affected by dielectric constant, density and conductivity

No need to reset

Things to consider:

Tank design must be considered

Heavy foam can be a problem

Blocking distance

Turbulent surface

Minimum dielectric constant

Request Manual 

ultrasonic level transmitter

How does an ultrasonic level transmitter work?

Ultrasonic measurements are based on the time-of-flight principle.SensorUltrasonic pulses are emitted, reflected by the medium surface, and detected again by the sensor. The required flight time is a measure of the distance traveled with an empty tank. Subtract this value from the total height of the tank to get the level.

Advantages of Ultrasonic Level Transmitter

Contactless (lowest cost)

Top installation

Accuracy is not affected by density changes, dielectric or conductivity

No media required for calibration

Things to consider:

Minimum density required

Bubbles are a problem

Blocking distance

Turbulent surface

Vapor/gas above liquid

Temperature difference between liquid and sensor

No vacuum (10 psia), no high pressure (44 psia)

Request Manual 

Capacitive Level Transmitter

How does a capacitive level transmitter work?

Principle of capacitive level measurementBased on changes in capacitance of the capacitor due to changes in liquid level formed by the probe and container walls. When the probe is in the air, the measured capacitance is lower. Once the container is full, the wider the probe's coverage, the greater the capacitance of the capacitor. A capacitance probe can be compared to a capacitor. As the tank fills, the probe's capacity increases. This change was analyzed electrically.

Advantages of Capacitive Level Transmitters

Very cost effective

Established principles

fast response

Interface measurements possible

High temperatures and pressures may be present

Things to consider:

Many versions

Conductor/Insulator

Probe Coatings - Chemical Compatibility

Ground reference tube

Nonmetal

Recalibrate with different media

Minimum span 10 pF

Bubbles can be a problem

Choosing a product doesn't have to be complicated!

You still haven't found the liquid level measurement product that suits you?

Please call our service hotline in China immediately: +1 (314) 325-4420

Let a DOWESTON sales engineer help you select
Please send me:
Quotation (5% online discount)
Detailed product documentation and more
Product Selection	Expert Answers	5% off for new customers
	What about the price? Get My Quote Now