Calibration of Refractometer

1.0 PURPOSE 

The purpose of the standard
operating procedure is to provide guidelines for calibration of Refractometer.

2.0  SCOPE 

The
scope of this standard operating procedure includes calibration of Refractometer.

3.0 RESPONSIBILITY

3.1    Section Incharge

3.2    Technical Manager

3.3    Q.A. Manager

4.0 PROCEDURE

4.1 
The Refractometer is calibrated with different liquids or glass test
piece of known refractive index.

4.2  Ensure that the surface of the prisms is
cleaned each time either with water or acetone

      
before using for the determination of the refractive index.

4.3  Put in a few drops of the reference liquid of
known refractive index in between the two prisms.

4.4  Circulate the water from a separate
thermostatic bath within the prism box using the inlet

      
and outlet tubes provided.

4.5  A thermometer to measure the temperature is
provided along with the instrument. By

     
 continuously circulating the
water a fixed desired temperature can be obtained.

4.6  Make the achromatic critical line coincide
with the index line with the field of view of the  telescope.

4.7  Keeping the telescope in the position take the
reading of the scale against the index mark.

     
 Record the observed refractive
index reading from the scale and correlate the same with

      
the reference reading.

4.8  Adjustment can be made by setting the scale
reading to correct value of refractive index to

   
   that fixed temperature by operating the pin
provided over the cone of the telescope till the

     
 critical line moves and coincides
with the cross line.