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Dean-Stark Apparatus is used to determine the water in petroleum products or bituminous materials by distilling them with a volatile solvent.

Ref. Standard

ASTM D95, D244

Country Origin


Make / OEM





This Warranty covers the defects resulting from defective parts, materials or manufacturing, if such defects are revealed during the period of 12 months since the date of purchase.


All pictures shown are for illustration purpose only. actual product may vary due to product enhancement.







The equipment comprises an electric heater with thermoregulator, glass still, support stand, condenser, receiving trap, clamp.

Two types of Dean-Stark exist one for use with solvents with a density less than that of water and another for use with solvents with a density greater than that of water.

The Dean-Stark apparatus typically consists of a vertical cylindrical glass tube, often with volumetric graduation along its full length and a precision stopcock at its lower end, very much like a burette. The lower end of a reflux condenser fits into the top of the cylinder. Immediately below the joint between the condenser and the cylinder is a sloping side-arm that joins the cylinder to a reaction flask. The lower end the side-arm turns sharply downward so that the side-arm is connected to the reaction flask by a vertical tube.


The reaction flask is heated. Boiling chips within it assist with the calm formation of bubbles of vapor containing the reaction solvent and the component to be removed. This vapor travels out of reaction flask up into the condenser where the water being circulated around it causes it to cool and drip into the distilling trap. Here, the immiscible liquids separate into layers (water below and solvent above it). When their combined volume reaches the level of the side-arm, the upper, less-dense layer will begin to flow back to the reactor while the water layer will remain in the trap. The trap will eventually reach capacity when the level of the water in it reaches the level of the side-arm. At this point, the trap must be drained into the receiving flask. The process of evaporation, condensation, and collection may be continued until it ceases to produce additional amounts of water.




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