CLOUD AND POUR POINT

AIM:

To determine the cloud point and pour point of the given sample.

APPARATUS REQUIRED:

Constant temperature bath

Thermometer

Flat bottomed test tube

DEFINITION:

Cloud point:

The cloud point of petroleum is the temperature at which a cloud or haze of

crystals appear at the bottom of the test jar, when the sample is cooled under prescribed

conditions.

Pour point:

Pour point is the lowest temperature expressed in multiples of 3 0C at which the

oil is observed to flow when cooled and examined under prescribed conditions.

THEORY:

The cloud point and the pour point are related to the flow conditions of crude and

its products at low temperature.

The cloud point gives the rough idea of the temperature above which the oil can

be handled safely, without any fear of congealing or filter clogging.

The pour point is determined to estimate the temperature at which a sample of oil

becomes sufficiently solid to prevent its movement by pumping.

The pour point temperature depends to a large extent on the thermal history of the

sample. Also the pour point indicates the waxy nature of the sample.

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PROCEDURE:

Oil is poured into the test jar up to the level mark of 51 to 57 mm. If

necessary the oil is heated until it is sufficiently enough to flow.

The test jar is closed with the cork carrying the thermometer. The cork

position is adjusted to make it fit properly into the tube.

The thermometer bulb is immersed so that the beginning of the capillary is

3mm below the oil surface.

The test jar surrounded by the air jacked is kept in the freezing mixture and

it is allowed to cool.

The falling temperature was observed with every degree fall of temperature

in the given sample. The tube was withdrawn from the air jacket for a

moment of about (2-3sec) and examined. It was then replaced immediately.

The temperature at which the cloudiness appeared was noted as the cloud

point.

The test tube was cooled continuously. The test tube was withdrawn often

for 5 0C fall of temperature to observe the flow or pour point of the sample.

The temperature at which the oil does not flow in the tube even when kept

horizontal for 5sec is recorded as pour point.

STANDARD POUR POINTS OF CRUDES USED IN INDIA:

Sl.No.

Crude name Pour point degC

1. Ankleshwar 18

2. North/Gujarat 27

3. Bombay high 30

4. Basrah -15

5. UMM Shaiff -15

6. High speed diesel 6

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RESULT:

Thus the pour point of the given sample was found.

(i) The cloud point of the sample _____0C.

(ii) The pour point of the sample _____0C.

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