Instrument knowledge|How to choose the correct type of guided wave radar liquid level meter?
Guided wave radar level meter, a liquid level measuring instrument in industrial production, is based on the time domain reflection principle (TDR) to complete the continuous level measurements of liquids, particles and slurry. Widely used in water storage tanks, acid and alkali storage tanks, slurry storage tanks, solid particles, small oil storage tanks, various conductive, non-conductive media, corrosive media such as coal bunkers, ash bunkers, oil tanks, acid tanks, etc. .
So how to correctly choose the guided wave radar level meter? Please see the following key selection points:
1.Confirm the viscosity of the measuring medium
When selecting a guided wave radar level meter, the viscosity of the measuring medium must be confirmed. If the measuring medium is very viscous, it is not suitable to use the guided wave cable pole. This kind of contact measurement method, hanging material will affect the signal transmission and reception and generate false signals.
2.Confirm the causticity of the measured medium
If the measured medium is a corrosive liquid, it is necessary to use a wave guide cable sleeve PTFE or FEP material.
3.Definition of range
The range of the guided wave radar liquid level meter is the vertical distance from the mounting flange surface to the bottom of the tank. At the same time, reserve the lowest probe of the cable at least 30mm from the bottom of the tank to ensure that the probe does not touch the bottom of the metal tank to generate interference signals. The cable can be reserved a little longer, you can cut it by yourself, but if you break it, you need to re-customize the cable. Therefore, we must confirm the length of the cable clearly when determining the technical parameters, so as to avoid the on-site measurement.
In addition, it is especially important to note that for the guided wave radar level meter with sleeve PTFE or FEP material products, the cable length cannot be shortened once confirmed。
4.Confirm whether there is stirring
Select the guided wave radar level meter to confirm whether there is stirring in the storage tank, where is the position of the fan blade, the blade is very close to the pipe wall, it is not suitable to use the guided wave radar level gauge, or add a bypass tube to measure. The cable or pole should be at least 300mm away from the pipe wall.
5.Confirm the dielectric constant of the measuring medium
If the measured dielectric constant of the liquid medium is very low, you can refer to the use of guided wave double cable or guided wave coaxial radar level meter, the effect will be better.
6.Fixing the probe tip of radar level meter
If the probe tip needs to be fixed, there are two kinds of fixing methods: insulated and non-insulated.
(一)Insulation fixing refers to the insulation fixing method when the measured dielectric constant is low and fixed on the bottom of the metal tank
(二)Non-insulating fixing refers to the non-insulating fixing method used when the dielectric constant of the measured medium is high and the tank is a metal material, a material with a low dielectric constant or a material very close to the dielectric constant of the measured medium.
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