To find a dew point, select a part of air in a vessel, it is desirable glass, hermetically close it and begin to cool. When steam in it begins to be condensed, take readings of the thermometer. It will also be a dew point. A dew point for this relative air humidity it is possible, using calculations.
It is required to you
- For carrying out measurements take a glass tight vessel, the psikhrometrichesky table, the table for definition of a dew point, two identical thermometers.
Instruction
1. Definition of a dew point by method of observation Select test of air in a glass vessel, and hermetically close it. Place this vessel in the refrigerator, at the same time, controlling temperature in it. When steam in a vessel is condensed, turning into liquid state (dew will drop out), take readings of the thermometer. It will also be a dew point for a concrete sample of air.
2. Calculation of a dew point Define relative humidity of air. For this purpose take two identical thermometers, it is better to take mercury. Wind a bubble of one of them with a gauze which then plentifully moisten with water. Wait several minutes and take readings of thermometers. Temperature on the damp thermometer will be lower or same, as well as on dry. Find the difference of temperatures of dry and damp thermometers.
3. According to the psikhrometrichesky table find relative air humidity. For this purpose find indications of the dry thermometer in an extreme left column. Find that difference of temperatures which was on dry and wet thermometers in the top line of the table. On crossing of these values in the table there will also be a value of relative humidity as a percentage. After learned relative humidity, by means of the table for definition of a dew point, find density of saturated steam at this temperature.
4. It is possible to use value of temperature taken by the dry thermometer. After that find the actual density of water vapor in air. To make it, value of relative humidity, increase by density of saturated steam and divide into 100% (ρ=φ\• ρн/100%). In the table for definition of a dew point, find that temperature for which this density of water vapor is saturated. It will also be required size.