Digitrans Industrial Controls



Description of the Digital Probe


PRINCIPLE OF OPERATION

The patented measuring method used in the Digitrans Digital RF Probe uses digital measurements only with a self compensating system to eliminate temperature effects in the measurement head. The effects of the capacitance and conductivity on the probe are measured in terms of frequency and then these frequency readings are converted to engineering units (Brix, concentration etc as required) by a digital controller.

DESCRIPTION

The complete system consists of a probe which fits into the vessel or pipe in which measurements are to be carried out and a seperate control unit. The control unit can be used to connect two RF probes. The probe body is made of 316 stainless steel.A sealed die cast aluminium box on the end of the probe houses the electronics module which is potted in epoxy for extra ruggedness. The controller, situated in another aluminium housing, has a LCD display and 16 key keypad and provides two 4-20 mA outputs for each probe.

A 4-20 mA input is provided for each probe to which temperature transmitters may be attached if temperature correction is required.

The controller and probes are connected by means of a coaxial cable which carries power to the probe and the frequency signal back from the probe.

pic of controller pic of dig. probe

Digital probe and controller.

APPLICATIONS

The digital probe is used wherever a linear indication of accurate brix readings is required. It may be used on high and low purity solutions but is of greatest use in high purities. The different model probes are used as follows

Model T2
Used in liquor, batch pans and refinery pans
Model T3
Used in continuous pans
Model T4
Used in batch pans

CALIBRATION

The instrument can be pre calibrated with the general characteristic of the product if this is known or for greatest accuracy can be calibrated in situ in the process. The process liquor has to be taken through the entire brix range that is anticipated while samples are taken and calibration readings are recorded in the controller for each sample.The samples are then analysed for brix and the results of laboratory analyses are entered next to the corresponding frequency readings. The controller carries out a regression on this data after which the instrument is automatically calibrated using the coefficients produced by the regression. The two outputs may be calibrated differently for two different products or in some cases it is possible to measure two different parameters on the same product. e.g. brix and ash

DIGITRANS PROBES

Models...........................Total Length....................Wetted Length
  • T2________________422 mm__________________165 mm
  • T3________________577 mm__________________320 mm
  • T4________________507 mm__________________250 mm
  • Probe diameter : 26mm
  • Probe body material : 316 stainless steel.
  • Connection into process : Adapter flange welded to vessel. Bronze socket bolted to flange with O ring seal.
  • Probe body temperature : Max 120o C
  • Probe head temperature : Max 70 o C
  • Electrical connection : N type coaxial socket
  • Cable to caontroller : RG 58 C/U 50 Ohm coaxial
  • Power consumption : Typically 60 mA 16 - 25 V DC
  • Protection class : IP 65. PCB encapsulated in epoxy for added protection

    DIGITRANS CONTROLLER - MODEL C2

  • Power requirement : 22-28 V DC - 300mA
  • Probe inputs : 2 off N type coaxial sockets
  • Program : EPROM
  • Paramater storage : Battery backed RAM
  • Display : 4 line alpha numeric LCD with backlight
  • Keypad : 16 keys - access through password
  • Ambient temperature : 50o C
  • Outputs : 4 X 4-20 mA into 500 ohms
  • Inputs : 2 X 4-20 mA two wire loop powered temperature probes
  • Isolation : Probe power isolated from ground and input power. 4-20 mA signals ground common with 24 Volt supply ground.
  • Terminations : Screw terminals in separate compartment to electronics
  • Protection class : IP65
  • Accuracy : +/- 0.1 brix with in situ calibration


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