# How does a psychrometer work?

## How does a psychrometer work?

A psychrometer is a device used to measure the humidity of air. It accomplishes this by comparing the difference in temperature between a dry thermometer bulb and a wet thermometer bulb that has lost some of its moisture through evaporation.

## How does a psychrometer measure humidity?

A sling psychrometer can be used to find relative humidity, which is expressed as a percentage. It is computed by multiplying the amount of moisture in the air at a given temperature, dividing by the maxi- mum amount of moisture the air could contain at that same temperature, and then multiplying the quotient by 100.

What does a psychrometer measure?

Psychrometers. A psychrometer measures humidity by taking both a wet-bulb and a dry-bulb temperature reading. The two thermometers are mounted in a sling which is swung rapidly around-and-around and then quickly read to obtain a steady wet- and dry-bulb temperature.

### How do you calibrate a digital psychrometer?

While holding down the °C/°F button, press and hold the ON/OFF button for 2 seconds to enter calibration mode.

### Why does the wet bulb temperature drop on a psychrometer?

The adiabatic evaporation of water from the thermometer and the cooling effect is indicated by a “wet bulb temperature” lower than the “dry bulb temperature” in the air. Combining the dry bulb and wet bulb temperature in a psychrometric diagram or Mollier chart, gives the state of the humid air.

How is humidity measured?

A device to measure relative humidity is 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.

## How do you measure humidity?

Divide actual vapor pressure by saturation vapor pressure and multiply by 100 to obtain a percentage using the formula Relative Humidity (percentage) = actual vapor pressure/saturated vapor pressure x100. The resulting number indicates relative humidity.

## Which temperatures can be measured by psychrometer?

With the psychrometer it is possible to determine the humidity, ambient, wet bulb and dew point temperature. Measurements up to 60 °C are possible with the psychrometer.

What can be measured by sling psychrometer?

relative humidity
A sling psychrometer is an instrument that measures the relative humidity and dew point in an area. A sling psychrometer has two thermometers: a wet bulb and a dry bulb. The wet bulb has a cotton wick over the bulb of the thermometer, which is moistened with room temperature water. The dry bulb is simply a thermometer.

### How does the aspirator psychrometer by Assmann work?

The aspirator psychrometer by Assmann serves for measuring the air temperature and the humidity. Two parallel mounted, equal thermometers with coloured petroleum are used. The bulb of one thermometer (wet bulb thermometer) is covered by a wick, which must be moistened for a measurement. The bulb of the other thermometer remains without wick.

### How does a hygrometer and a psychrometer work?

A psychrometer is a type of hygrometer, a device that measures relative humidity. A hygrometer uses two thermometers, one dry (dry bulb) and one covered in a fabric saturated with distilled water (wet bulb). Air is passed over both thermometers, either by a fan or by swinging the instrument, as in a sling psychrometer.

What kind of sensors are used in the psychrometer?

Today, the historic Assmann psychrometer has been abandoned and has been substituted with automatically operated electric fans and more advanced temperature sensors, e.g. platinum resistance, thermocouples and thermistors.

## Which is the correct way to handle a psychrometer?

Another frequent misuse is to handle a psychrometer with raised arm, as the air heated by the body follows the upward chimney path along the arm and is then aspirated by the psychrometer fan. The correct position is to handle the instrument with a lowered arm or to hang the instrument from an extension pole.