BACKGROUND
Dew Point Method
Dew point is defined as the temperature to which the mixture of air water vapour must be cooled at constant humidity to become saturated. Formation of mist and disappearance of mist are considered and dew point is determined.1,2 Dew point temperature is noted on the temperature ‘X-axis’ and move vertically on the psychrometric chart.
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The intersect point at saturated curve (100%) is identified. The coordinates of the point (temperature, humidity) are noted. The Y-axis point is the humidity of air. These values are substituted in the equation.3,4
% Relative humidity = Humidity of air / Humidity of saturated air × 100
Aim: To determine the humidity and relative humidity by Dew point Method.
REQUIREMENTS
Apparatus
- Round bottomed long neck flask (100 ml)
- Thermometer, 1100c
- Tripod stand
- Water
- Ice
PROCEDURE
A round bottom long neck flask was thoroughly cleaned and dried the external surface. Water was filled into the flask up to 2/3rd of the volume. The above flask was kept on a tripod stand. A thermometer (1100c) was dipped in the water. Crushed ice is slowly added to the water (in the flask) is lowered; mist begins to form on the outer bottom surface of the flask. At this point, the temperature is noted.
This is the dew point (temperature). In psychometric chart, from the temperature (X-axis) moved vertical up until the saturation curve and identified the intersecting point are noted. The Y coordinate is the humidity.
Observations and calculations
| Trials | Dew point 0c | HumidityRelative humidity | ||
| Mist appearance | Average value | |||
| 1 | ||||
| 2 | ||||
| 3 | ||||
CONCLUSION
Humidity and relative humidity are found to be ____.
REFERENCES
- Subrahmanyam CVS, Setty JT, Sarasija S. Laboratory manual of pharmaceutical engineering (Unit operations), Delhi Vallabh Publications.
- Pharmaceutical Engineering by K.Sanbamurty (New Age International, New Delhi)
- Cooper and Gunn’s Tutorial Pharmacy Edited by S.J.Carter (CBS Publishers, Delhi)
- Pharmaceutical Dosage forms by Aulton.(Churchill Livingstone, Edinburg)
Also read:
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- Determination of saponification value of fat (coconut oil)
- Protein denaturation by egg albumin method (in vitro)
- Analgesic activity study of drugs by hot plate (Eddy’s hot plate) method
- Study of local anesthetics by Infiltration anaesthesia in guinea pig
- Study of local anesthetics by Surface anaesthesia on the cornea of rabbits
- Study of local anesthetics by Spinal anaesthesia in rats
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