The range of chemicals shipped in bulk now has been increased enormously and to maintain product quality any contaminants in the chemical cargo need to be observed.
Presence of free water in non water-soluble products can, very roughly be determined on board by the following
simple methods.
i) Warm a sample of the product in a test tube or in a bottle.Water will then collect at the bottom of the tube and
can be seen after some time.
ii) Drop a little of the product on to an electric hot plate. A crackling sound indicates that water is present. Can be
used on lubrication oils etc.
Other methods for non water-soluble products are:
i) The product is kept at a temperature slightly above 100 degr. C for a period of time and is accurately weighed
before and after heating (for products with a boiling point above about 125 degr. C).
ii) Use a centrifuge and see if there is any water at the bottom of the test tube.
iii) A distillation method according to ASTM D 95-62 (Dean Stark) is often used for oil products with
relatively high boiling points (fuel oils, gas oil, asphalt, creosote). A sample is dissolved in xylene and the
solution boiled in a glass retort. The vapours pass through a condensor. The water condenses and can be
measured in a graduated tube.
An accurate determination of water contents can be made with a "Karl- Fischer" - reagent. This method is suited
for laboratory work only.
Very small amounts of water in some products can be observed as a turbidity in a clear liquid when a sample is
cooled down to a low temperature (cloud point). As a reference calibrated samples are used with known water
contents at defined temperatures. The method is used primarily for chlorinated hydrocarbons such as carbon
tetrachloride and trichlorethylene where water might be a severe contaminant also in minute concentrations
(example: for trichlor ethylene a max water contents of e g 0, 006 %). (Remark: "cloud point'' also means the
temperature at which wax needles may form in certain oils, e g in gas oil, upon cooling. Ref: ASTM
D 2500-66).
Related Info:
Determining water contamination in chemical cargo
Chloride contamination in chemical cargo - how to resolve?
Varoius product contamination in chemical cargo - how to resolve?
Using acid wash method for a cargo of aromatics contaminated by a previous oil cargo
APHA (Hazen) method for determining color of very light chemical products
Use of Oxygen analysers
Cargo vapour detection equipment
Chemicaltankerguide.com is merely an informational site about various aspects
of chemical tankers and safety tips that may be particular value to those working in: Chemical Handling, Chemical Storage,
Liquefied Chemical Suppliers, Chemical Shipping, Chemical Transportation, Chemical Terminals, Bulk Chemical Services and
Chemical Processing. If you are
interested in finding out more about chemical tanker guideline please visit IMO official website. For any comment please
Contact us
Copyright © 2011 Chemical Tanker Guide.com All rights reserved.