DETERMINATION OF WATER CONTENT (DEAN AND STARK METHOD)

STANDARD

  • IS: 1211-1978

OBJECTIVE 

  • To determine the water content of asphalt bitumen and fluxed nature asphalt, Crude coal tar, Road tar, Cut back bitumen, Digboi type cutback bitumen and creosote and anthracene oil.

APPARATUS

  • Flask of 500ml capacity made of heat resistant glass well annealed and as free as possible from striac and similar defects. The top of the neck shall be ground to from the socket of a ground glass joint.
  • Condenser made of heat resistant glass well annealed and as free as possible from striac and similar defects.
  • Receiver made of heat resistant glass well annealed and as free as possible from striac and similar defects.
  • Heat resistant glasses well annealed and as free as possible from striac and similar defects.
  • 100 ml graduated cylinder
  • A suitable Gas burner or Electric heater Solvent
  • The solvent may be any one of the following
  • Blend of 20% by volume of industrial-grade Tolune and 80% by volume of industrial-grade Xylene.
  • Petroleum or coal tar naphtha free from water yielding not more than 5% distillate at 125°c and not less than 20% at 160°c
  • Petroleum spirit with a boiling range of 100 to 120°C.

PROCEDURE

  • Take approximately about 100 gms of the sample and pour it into the flask.
  • Add 100ml of solvent.
  • Attach the flask to the Dean and Stark condensing and collecting system.
  • Heat the flask at such a rate that the condensate falls from the end of the condenser at a rate of two to five drops per second.
  • Continue the distillation until the condensed water is no longer visible in any part of the apparatus except the bottom of the graduated tube and until the volume of water collected remains constant for a period not less than five minutes.
  • Remove the precipitant ring of the condensed water in the condenser tube, if any, by increasing the rate of distillation by a few drops per second.
  • Wash droplets of water which adhere to the lower end of the condenser tube into the receiver with solvent or carrier liquid using the spray tube.
  • Insert a loose plug of cotton wool into the top of the conditioner tube to prevent the condensation of atmospheric condenser tube moisture in the tube.

REPORT

  • Report the results as water content to the nearest 0.05% by weight if 2inl receiver has been used and to 0.1% if the lO nil receiver has been used with lOO grams of sample.

PRECISION
•              Duplicate determinations shall not differ by more than the following

Water collected Repeatability Reproducibility
0 to 1.0 ml   0.lml  0.2ml
1. l to25 ml 0. l to2%of their mean 0.2ml or 10% of mean whichever is greater

                                                               

Leave a Comment

Your email address will not be published. Required fields are marked *