Description
TQC Bacharach Sling Psychrometer
Bacharach type sling Psychrometer for indicating percent relative humidity on the basis of the wet bulb-dry bulb thermometer principle. The plastic case of the instrument equipped with conversion scale for calculating the percent relative humidity.
Most inspectors are using red spirit thermometers because they do not contain mercury which is a very toxic heavy metal. Make sure that the column is not separate. Often, especially when left in the heat or after shipping, the red column will separate. This will result in inaccurate reading. Sometimes by putting the thermometer in ice water following by hot (not boiling) water, the column can be fix. If it cannot be fix, replace it.
Using a Bacharach Sling Psychrometer
Hygrometer usually uses for measures the air relative humidity. The simplest hygrometer – a sling psychrometer – consists of two thermometers mounted together with a handle attached on a chain. One thermometer is ordinary, and another with a cloth wick over its bulb is a wet-bulb thermometer.
When a reading is to be taken, the wick is first dipped in water and then the instrument is whirled around. During the whirling, the water evaporates from the wick, cooling the wet-bulb thermometer. Then the temperatures of both thermometers can be read.
If the surrounding air is dry, more moisture evaporates from the wick, cooling the wet-bulb thermometer more so there is a greater difference between the temperatures of the two thermometers. If the surrounding air is holding as much moisture as possible – if the relative humidity is 100% – there is no difference between the two temperatures. Meteorologists have worked out charts of these differences for each degree of temperature so that the observer can find relative humidity easily.
Relative Humidity – Temperature in Celsius
Below table uses to estimate the relative humidity of air if dry and also wet bulb temperatures are known.
Dry Bulb Temperature = Tdb / Wet Bulb Temperature = Twb
Relative Humidity – Temperature in Fahrenheit
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