4/20mA piezometric submerged level probes and sensors

Technical data CNR piezometric submersible level sensors and probes. :

CNR's 4/20mA piezometric immersed level probes and sensors are submersible transmitters using piezo-resistive technology for monitoring and measuring the level of stable or moving liquids at differential pressure. These are the essential accessories for your remote management.

Documentation probes and submerged sensors: click here

- Measuring range of submerged level sensors:

The measuring range or full scale (height of water for which the CNR submerged level sensor or probe gives 20mA) is definable between :
- 0 to 50cm of water and 0 to 30m of water,

- Signal type :

CNR piezometric level probes and sensors deliver a 4/20mA signal on two wires. On request, these CNR piezometric level probes or sensors can be delivered in an inverted signal version.

- Diameter of submerged piezometer probes and level sensors CNR :

The CNR 4/20mA piezometric level sensors have a diameter of 21.4 mm.

- Weight of piezometric submerged level probes and sensors CNR :

In order to avoid any drift of the measurement in case of eddies, the CNR 4/20mA piezometric immersed level probes or sensors must be of a weight/volume ratio adapted to the application.
This is why CNR piezometric level sensors have a weight of 180 g (+50 g / meter of cable)

- Body material for piezometric submerged level probes and sensors CNR :

The body of the CNR 4/20mA piezometric immersed level sensors and probes is made of 316L stainless steel.

- Compliance with standards :

The CNR PARATRONIC 4/20mA immersed piezometric level sensors or probes not only comply with the standards in force but also exceed the minimum EMC standards required by these standards. For example, the resistance to fast transients is level 4 and the resistance to lightning strikes is greater than 20 kA (wave 8/20).

- Measurement Accuracy :

The accuracy of the measurement given by CNR' s immersed piezometric level probes and sensors does not depend on the rate of variation of the level, nor on the distance between the acquisition station, remote management, and the sensor (level probe). These parameters have no influence on the accuracy of the measurement.

Overall accuracy of a CNR : better than +/-0.3% typ. of full scale.

This overall accuracy of a piezometric submerged level sensor is broken down into four distinct elements :

The sensitivity or resolution of the probe: the smallest change in level detected by the sensor,
The temperature drift of the probe: variation of the signal according to the variation of the water temperature (for a constant water level).
Linearity of the sensor: accuracy of the piezometric submerged level sensor as a function of the water level,
Repeatability and probe hysteresis: difference in the signal delivered for two measurements of the same water level.

Sensitivity or resolution of a CNR probe: better than +/-0.01% typ. of full scale.

Temperature drift of a CNR sensor: better than +/- 0.02% typ. of full scale per °C deviation from the set temperature.

Linearity of a CNR probe: better than +/-0.15% of full scale.

Repeatability and hysteresis of a CNR probe: better than +/- 0.3% of full scale.

– Distance station / piezometric submerged level sensor :

CNR piezometric submerged level probes and sensors deliver a 4/20mA signal over two wires. As a result, the distance the signal is carried has no influence on the accuracy of the measurement or on the wear of the parts, or even on the current consumed by the 4/20mA probe.
The maximum distance between the piezometric submerged level sensor and the remote control unit depends solely on the minimum operating voltage of the piezometric submerged level sensor and the supply voltage. For example, if the remote management system delivers a voltage of 12V, the maximum distance between the CNR piezometric immersed level sensor and the station is more than 7 km and if the station delivers a voltage of 24V the maximum distance is more than 20 km.

For distances greater than 20 km, and still without degrading the accuracy of the measurement, simply increase the supply voltage.

- Operating voltage of the cnr probes:

CNR' s submerged piezometric level sensors operate at any loop power supply voltage between 6VDC and 38VDC.

- Reverse polarity on CNR probes:

All PARATRONIC piezometric submerged level probes and sensors are protected against polarity reversal.

- Operating temperature of the CNR probes:

The CNR piezometric immersed level sensors operate for the measurement of liquids with a temperature between -20°C and +60°C (in liquid phase)

- Heating time of a PARATRONIC sensor:

Les capteurs de niveau immergés piézométriques CNR délivrent un signal 4/20mA sur deux fils en permanence du moment que la boucle est alimentée. Le temps de chauffe du capteur, ou temps d’alimentation minimum nécessaire afin d’obtenir le signal, est <300ms pour les CNR .

 

- Cable and venting of CNR probes:

The structure of the cable and the dimensional, mechanical and chemical characteristics of the elements that make it up are part of the technologies resulting from PARATRONIC 's experience and research and development capabilities. This element is one of PARATRONIC 's proprietary know-how and plays an important role in differentiating PARATRONIC's piezometric submerged level sensors from other piezometric submerged level probes on the market.

The cable used for probes or CNR piezometric immersed level sensors allows the piezometric immersed level sensor to be put at atmospheric pressure without using a capillary, thus avoiding the inconvenience of crushing, pinching, bending or clogging (by a drop of water) of the said capillary and avoiding the need to use "filters".

In addition, the flexibility of the cable allows for installations with bends, angles and tortuous runs.

Its "triple skin" structure guarantees a long-term watertightness of the cable (and therefore of the level probe) even in chlorinated, ozone-treated or extremely polluted water.

Finally, the double shielding system (including a stainless steel shield) avoids the problems of mechanical damage to the cable, in particular the wear and tear of the cable on the wellheads when the CNR piezometric submerged level probes and sensors are installed and removed.

– Integrated lightning protection system:

PARATRONIC 's CNR 4/20mA submerged piezometric level probes and sensors are guaranteed to withstand lightning strikes without the need to install any external protection system. This feature is the result of 25 years of experience and research and development in this field. This know-how plays a major role in differentiating PARATRONIC piezometric submerged level sensors from other piezometric submerged level sensors on the market. Indeed, PARATRONIC 's CNR 4/20mA piezometric immersed level sensors can withstand atmospheric surges of 20kA intensity without damage, whether these surges are carried by the cable or come from a shock in the ground whose potential distribution would touch the sensor.

This technology has three major advantages:

- It is much more effective than simply installing a surge protector , as the latter protects, in the best case, only against surges carried by the cable.

 

- It avoids the cost of wiring and connection and the periodic checking of the good condition of a lightning arrester,

- It is effective whatever the conditions of installation; for example, a lightning arrester only plays its role correctly if its earth cable is short, which is impossible in the case of an immersed piezometric level sensor remote from the station.

- Mounting devices for submersible sensors:

The CNR 4/20mA piezometric immersed level sensors are systematically delivered with a "cable clamp" allowing their fixing.

- Adjustment and parameter setting mode for submersible probes:

CNR 4/20mA submerged piezometric level sensors do not require any adjustment or parameterisation other than those made at the factory.

- Maintenance conditions for submersible probes:

No special maintenance is required for the use of CNR 4/20mA piezometric submerged level sensors.

Cleaning: No cleaning is a priori necessary. In fact, several thousand CNR piezometric immersed level sensors are currently immersed in wastewater treatment plants or lift stations. Such applications correspond to use in water where the load of sand, grease, sludge and aggressive products creates risks of clogging that are much greater than in rivers. In these extreme conditions, cleaning is limited to rinsing the submerged piezometric level sensor about once a year.

Preventive replacement of parts: The CNR 4/20mA piezometric immersed level sensors do not have any wearing parts, except for the measuring cell, whose replacement requires an intervention in the factory for reasons of calibration and sealing.

- Installation requirements for the Piezometric Submersible Level Sensor :

There are two requirements for the installation of CNR 4/20mA piezometric submerged level sensors:

- As the cable is used for atmospheric pressure (without capillary), it must be ensured that its end (connection to the data acquisition unit or to a connecting cable) is out of water and that, in the case of a junction box, it is not of the "resin casting" type.

- As the cable of the immersion probes is used for atmospheric pressure (without capillary tube), care must be taken not to injure it when inserting it.

 

See also the documentation: documentation for submersible level sensors and probes

Updated 29/08/2014.

 

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