Berthold Industrial Systems

Density Gauge LB 386-1C

Advantages

Contactless continuous measurement using gamma absorption
Easily fitted to existing pipeline or into container
Independent of colour, temperature, pressure, viscosity, conductivity and chemical properties of the product
High long-term stability (+ 0.1%) achieved by automatic drift compensation
Output of measured results and calibration in the unit to be measured - g/cm³, %, ºBx, ºBe, g/l

LB 386 - powerful evaluation unit for density measurement

Some Practical Applications - Concentration measurements in the chemical industry for acids, alkalis and saline solutions; in the food industry for sugar solutions, evaporated milk, chocolate, soup seasoning etc. Monitoring chemical conversions which result in density changes: eg. polymerization, crystallization etc. Solid content of liquids eg. sludge content in pipelines (extraction of ores or minerals), bauxite content in lyes for aluminium production, monitoring the precipitation of coal sludge in coal washing and sewage sludge in sewage plants.

Flow rate and weight analysis If the pipe cross-section and the flow velocity (eg. measured by a flow meter) are known, the Density Measuring System LB 387 will provide the weight throughput per unit time.

Measuring Principle The radiation emitted by a gamma source is attenuated as it passes through matter. This absorption is an exponential function of measuring distance and density. If therefore, the measuring path is constant, the attenuation of radiation is an indication of the product density.

A sensitive detector (scintillation counter) measures the residual radiation and supplies a digital signal dependent on radiation intensity. The drift compensation, incorporated in the scintillation counter, compensates for the effects of temperature variation and component aging. This results in a high long-term stability of + 0.1% relative to the gamma radiation intensity.

clamp-on for larger pipes Clamp-on

Radiation Source and Shielding In most cases a 137 Cs source (half-life 30 years) is used as a radiation source. The actual radioactive substance is double encapsulated in welded stainless steel. Each individual layer is checked for leaks after welding. The source capsule has been tested by the Federal German Bureau of Standards. It meets the highest safety standards (ISO C 66646). The shielding container consists of a cast iron housing filled with lead. For very corrosive environmental conditions, a housing made of stainless steel can be supplied.

Using the scintillation counter as a detector allows the use of low source activities and small diameter radiation beams. Since the radiation is almost completely absorbed in the scintillation counter, Radiation Protection Regulations are met in most cases without any additional shielding.

S-shaped section for small diameter pipes

Evaluation Unit LB 386-1C The computer in the evaluation unit LB 386-1C converts the pulses from the detector to an output signal 0/4-20mA. A special curve fitting program supplies a current signal proportional to the unit of measurement- even if this means the current signal is not proportional to the density.

The evaluation unit can be supplied as a single or dual channel version, and both channels can be calibrated separately. The supply for the detector for each channel can also be switched off separately, and the second measuring channel can be connected at a later date without any problems. If temperature variations occur, the temperature compensation relates the unit of measurement to a reference temperature.

Calibration A sophisticated calibration program allows precise start-up. The special properties of the product and the measuring point are automatically taken into consideration. Only one measuring point in needed for start-up, but up to 10 measuring values can be used to obtain an accurate calibration.

LB 386-1C - an evaluation unit with many advantages

Versatile
For 3 different products the LB 386-1C stores calibration data, temperature compensation and range of current outputs
Selection of data sets via keyboard or external switch
Two isolated current outputs per channel 0/4-20mA. Output 1 for density or concentration, output 2 for either density/concentration or product temperature. The ranges for both current outputs are freely selectable
Input for temperature signal: Pt 100 or 0/4-20mA
Test function for detector signal and current outputs
Calibration possible with only one measuring point. For highly accurate measurements one may use up to 10 calibration points. An exact linearisation of the output signal is achieved even with 'difficult' products such as NaOH or H₂SO₄
Reliable
Storage of all calibration data in EE-Prom
Detector failure alarm
Check of the evaluation unit by watch dog
Alarm via relay output
Interference from external sources can be suppressed, eg. during non-destructive testing
The measurement can be stopped by external contact at which the last measured value will be held, eg. during an empty pipe condition
Operation via foil keypad. To protect the system against unauthorised data manipulation, the keypad can be locked by entering a password
Data Outputs
Printout via RS232 printer interface for calibration data, product temperature and average value of density or concentration. The measured value can be averaged over an interval freely selected between 1 and 1440 minutes
RS232 interface for data transfer to computer

In-line

Application Notes

for more information, email

SE Asia and Australasia: industrial@berthold.com.au

North America: usinfo@berthold.com.au

Europe: euroinfo@berthold.com.au

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