Semuda ::

SEMUDA JUTE MOISTURE METER

Principle and Features :

The Meter is directly calibrated for moisture regain % in Jute Fabrics and consists of a fully Transistorised circuit. The meter is powered from four flash light cells. The working principle is to measure the electrical conductivity of jute materials, which changes with moisture content. The instrument can also be calibrated directly for jute seeds. The meter is light, handy and easy to operate. The calibrations are not materially affected by the variations in temperature, humidity and battery voltage.
Applications :

Although the meters are designed and constructed for testing of jute and jute goods, by suitable modifications and calibrations these may be used for other allied materials, such as jute seed, viscose, coir, wood, grain, paper, kapas, lint, cotton fibre, silk, soil, tea, etc.
Battery Consumption :

The four flash-light cells used in Model III and two cell in Model II require replacement generally after six months under normal conditions of use. An automatic cut-out device is provided on the meter which eliminates unnecessary consumption of battery current when the meter is left without switching off through oversight.
Measuring Range :

      Model – II .. .. 9 to 40%
      Model – III .. .. 8 to 70%
   Moisture regain of jute fabric ( on dry weight basis ).
Electrode :

      The electrode used for testing fabrics contains two brass contact rings fitted flush with the plastic head of electrode. A spring-loaded pressure- controlling device is provided inside the electrode; the electrical connection of the electrode with the main circuit is completed only when a predetermined pressure has been applied on the electrode. With lower or higher pressure on the electrode the circuit remains incomplete and no reading is obtained on the meter.

      A separate electrode ( consisting of pointed contact pins ) for testing raw jute , slivers, roves and yarns, are also available.
      Special electrodes have been designed and constructed for testing the moisture content of jute seeds in bags or small containers.
Methods of operation and test :

      a) Before using the meter, brush the dial of the meter, the bottom surface of the electrode, the plug pins and the Check Resistors so that the meter and its accessories are clean.

      b) Put the main switch at the bottom of the panel to the “ON” position and throw the Scale-Selector switch ( the upper one ) the position L, ( this indicates that the readings should be recorded on the ‘L’ ( outer ) scale of the meter i.e. from 8 to 19% regain ).

      c) Adjust the ‘Y’ ( right hand ) control to bring the pointer in line with the mark ‘Y’ ( at right-hand end of the scale ).

      d) Press the white ‘Push” switch and adjust the ‘X’ ( left-hand ) control to bring the pointer in line with the mark ‘X’ ( at the left-hand end of the scale ), and release the ‘Push’ switch.

      e) To check calibration, insert the resistor into the electrode socket and observe the meter reading, which should correspond to the value specified on the resistor. If it does not correspond, the meter is not in order and should not be used.

      f) Place the electrode on the material under test in such a way that the entire area of the electrode face is in contact with the sample and apply pressure gradually on the electrode until the meter indicates the present regain of the material. For too low or too high pressure there will be no reading at all on the meter. Very high pressure should be avoided, since this may damage the spring.

      g) If the pointer reads beyond the scale ‘L’, change the Scale-Selector switch to the position ‘H’ and re-set adjustments ( as above ), if required and carry out the test.

      h) Hot samples of fabrics or bags drawn from freshly opened bales should be allowed to cool down for about 5 to 10 minutes before testing with the moisture meter. A higher reading than the correct value is usually obtained on hot materials.

      i) After the test is completed, the main switch should be put off.
Method of tests on jute seeds :

      Two separate electrode (1) two long-pin type and (2) pressure control type (with a brush container ) are provided along with the instrument. The long- pin type electrode is for use on seeds contained in bags or seeds lying in heaps on the floor. The method of operation is to introduce the electrode into the material under test upto its full length and to note the reading obtained on the meter scale. A number of readings should be taken at different regions of the samples to obtain an average value.

      When samples are obtained in small quantities the pressure control electrode should be used. The method is to fill cylindrical container to approximately 3/4th of its depth with the sample of seed to be tested. The pinned head of the electrode should be then introduced into the cylinder and pressed gradually until the connection inside the electrode is completed at a predetermined pressure to be applied on the electrode. The reading on the meter scale obtained under this condition is to be recorded.

      It may be again pointed out that at a pressure higher or lower than the predetermined value, the electrode connection remains incomplete and the meter registers no reading at all.
Maximum Dimension and Weight :

      Model II – 19.0 cm. X 14.0 cm. X 7.8 cm.
      Model III – 19.6 cm. X 16.3 cm. X 11.2 cm.
    The weight of the meter is approximately 3 Kgs.
Maintenance :

Like all electronic Instruments, the meter is delicate and should be handled with reasonable care. The maintenance normally required is as follows :

(a) Replacement of battery

The access to the battery is obtained after removing the four screws fixing the panel with the meter box. The cells are fitted in a chamber containing two contact springs at one end. The flat bottom of the cells (-ive Terminals) should be in contact with the springs. While replacing the cells, care should be taken that the polarities are not reversed. The procedure should be to replace the cells one by one exactly in the same position and configuration. The cells are not to be changed when the initial “X-Y” settings cannot be made.
Servicing :

Servicing can be carried out at our Laboratory. A stock of spare parts is usually maintained.