CS-300RF admittance level gauge

1Measurement principle

CS-300The series RF level gauge is a new type of capacitive level measuring instrument. Due to the use of radio frequency technology and microcomputerseThe code circuit technology solves the problems of large temperature drift, difficult calibration, and fear of adhesion in traditional capacitive level gauges. It can be widely used for continuous measurement of various liquid and solid levels and interfaces, as well as switch alarm and interlock control. Especially when measuring in environments with high temperature, strong corrosion, strong adhesion, and large dust, it is incomparable to other types of level gauges and level switches.

The RF admittance level gauge is developed based on the capacitive level gauge, consisting of a capacitive level sensor and a detection capacitor circuit. The basic working principle is that the capacitive level sensor converts the level into a change in capacitance, and the change in liquid level is proportional to the change in the probe capacitance of the level gauge. Then, the level value is obtained by measuring the capacitance.

　 Capacitive level sensors operate based on the principle of cylindrical capacitors. Its structure is similar to2The length isLThe radii areRandrA cylindrical metal conductor with insulating material in between, when the medium charged in the middle has a dielectric constant of ε1When using gas, the capacitance of the two cylinders is:

C1 = 2πε1L/R(㏑R/r)

(1)If a part of the electrode has a dielectric constant of ε2When immersed in non-conductive liquid, there must be an increase in capacitance △CGenerate (due to ε)2>ε1）At this moment, the capacitance between the two polesC=C1+△CIf the electrode is submerged for a length oflThe capacitance increment is:

△C = 2π(ε2 -ε1)ι/ (㏑R/r)

（2）When ε2、 ε1、R、rWhen unchanged, the incremental capacitance △CLength of immersion with electrodeslDirectly proportional, therefore measuring the capacitance increment value can determine the liquid level height.

　　 If the measured medium is a conductive liquid, the electrode should be covered with an insulating material (such as polyethylene) as an intermediate medium, and the liquid and the outer cylinder together serve as the outer electrode. Assuming the dielectric constant of the intermediate medium is ε3The submerged length of the electrode islAt this point, the capacitance of the capacitor is:

　 　C = 2πε3ι/ (㏑R/r)

（3） Among them:RandrThey are the outer radius of the insulation cover layer and the outer radius of the inner electrode, respectively. Due to ε3 As a constant, thereforeCgivelDirectly proportional.

Main characteristics

Strong adaptability: It can work reliably in environments with high temperature, strong corrosion, strong adhesion, and large dust

• Easy calibration: Calibration can be completed in one go using any two point object positions

• No maintenance required: Due to the simple structure of the sensor and the absence of movable parts, there is no need for maintenance once it is put into operation

Widely applicable: both liquid and solid materials can be used

2Overview of Instruments

model CS-300A CS-300B

application Strong acid and strong alkali,Corrosive liquids with complex process conditions/slurry/Solid particles Large volume ordinary liquid/slurry/Solid particles

Probe form Rod style Cable type

maximum range 3.6m 20m

measurement accuracy ±0.25%FS ±0.25%FS

Process connection Thread or flange Thread or flange

Measuring rod material PTFE+316LStainless steelPFA PTFE+316Lstainless steel, PFA

process temperature -40℃～280℃ -40℃～280℃

Supply Voltage 24VDC±10% 24VDC±10%

Process pressure 0～4MPa 0～1.6MPa

signal output 4．．．20mA HARTagreement 4．．．20mA HARTagreement

Explosion proof protection EXIAIICT6/IP67 EXIAIICT6/IP67

local display LCDLCD,5position-6position LCDLCD,5position-6position

3Installation requirements

When installing sensors, it is necessary to set up reference electrodes on site, such as metal tank walls and other conductors. At this time, it is necessary to ensure that the instrument housing maintains good contact with the set reference electrodes. If the container wall is insulated, the case must be grounded with a wire.

Top installation:

The top installation should be kept away from the inlet to avoid large fluctuations in the liquid level during feeding, especially when measuring heights exceeding3.6When using a storage tank or process container, a soft cable RF admittance level gauge should be selected, and a heavy hammer should be fixed at the lower end of the soft cable to avoid significant shaking of the soft cable when liquid enters.

Hard rod sensors are generally not fixed at the bottom, and in special cases, fixed supports can be added at the bottom or in the middle. Cable sensors need to be fixed with a heavy hammer or bottom anchor

Several installation method diagrams:

Installation of cable probe

When measuring heights exceeding3.6When using a storage tank or process container, a soft cable RF admittance level gauge should be selected, and a heavy hammer should be fixed at the lower end of the soft cable to avoid significant shaking of the soft cable when liquid enters.