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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 is equipped with conversion scale for calculating the percent relative humidity.

Using a Sling Psychrometer

Relative humidity can be measured by an instrument called a hygrometer. The simplest hygrometer – a sling psychrometer – consists of two thermometers mounted together with a handle attached on a chain. One thermometer is ordinary. The other has a cloth wick over its bulb and is called 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 are 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

The table below can be used to estimate the relative humidity of air if dry and wet bulb temperatures are known.
Dry Bulb Temperature = Tdb / Wet Bulb Temperature = Twb
Relative Humidity – RH (%)
Tdb – Twb
(oC)

Dry Bulb Temperature = Tdb / Wet Bulb Temperature = Twb

Relative Humidity – RH (%)
Tdb Twb
(oC)
Dry Bulb Temperature – Tdb (oC)
1518202225273033
19091919292929393
28082838485858687
37173757677787980
46265676870717374
55357596164656769
64449525457596163
73642454751535558
82834384145475053
92127313439414548
101320252833364043

Relative Humidity – Temperature in Fahrenheit

Relative Humidity – RH (%)
Tdb Twb
(oF)
Dry Bulb Temperature – Tdb (oF)
6064687276808488
19495959596969696
29090909191929292
38485858687888889
47880818283848485
57375767879808081
66870727375767778
76366676971727374
85861636567687071
95457596163656668
104952555759616364
    Art. nr. TM0082

    Spare Thermometer set for TQC Sling Psychrometer

    SKU: TM0082

    Art. nr. TM0083

    Spare Wick for TQC Sling Psychrometer, 1m

    SKU: TM0083

    Art. nr. TM0082

    Spare Thermometer set for TQC Sling Psychrometer

    SKU: TM0082

    Art. nr. TM0083

    Spare Wick for TQC Sling Psychrometer, 1m

    SKU: TM0083

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