Wet And Dry Bulb Hygrometer Principle

This type of hygrometer uses two basic mercury thermometers one with a wet bulb one with a dry bulb.

Wet and dry bulb hygrometer principle.

Hygrometer contains two thermometers one is called dry bulb and second as wet bulb. Moreover it is the most common hygrometer and easily usable. From table mean r h. 76 70 65 70 76 70 76 70 70 76 10 71 9.

As our testing lab is not air conditioned so the dry bulb hygrometer is of course need for the accurate of all expects. The instrument is made up of two indentical thermometers one a wet bulb and the other a dry bulb. In order to measure the dry bulb and wet bulb temperature the psychrometer frame glass covering thermometer arrangement is rotated at 5 m s to 10 m s to get the necessary air motion. Wet bulb plays main role in the measurement of the humidity.

An important condition is that correct accurate measurement of wet bulb temperature is obtained only if air moves with velocity around the wet wick. Dry and wet bulb hygrometer. Get it thu sep 24 tue sep 29. Wet dry bulb hygrometer wall mounted thermometers eisco labs.

As the water around the wet bulb evaporates the bulb cools down because the water absorbs heat from its surroundings as it changes phase. Humidity measurement instruments usually rely on measurements of some other quantities such as temperature pressure mass a mechanical or electrical change in a substance as moisture is absorbed. Dry bulb reading wet bulb reading difference r h. At a lower humidity water evaporates more actively so that the wet bulb temperature lowerssharply.

Wet and dry bulb psychrometers are the most simple and common way of measuring humidity. The aspirated psychrometer measures humidity by measuring the difference between the dry bulb temperature and wet bulb temperature. The principle behind a psychrometer is fairly simple. One is dry and the other is kept moist by wrapping the bulb in a wet piece of cloth.

The wet bulb thermometer has it s bulb wrapped in a tight fitting muslin cloth material wicking which is soaked in. Masons wet dry bulb hygrometer is used to calculate the water vapour content relative humidity of air at a given temperature. The device contains two thermometers. According to their names dry bulb remains dry in the air and the et bulb is surrounded by a cotton wick that is dipped in the water.

A hygrometer is an instrument used to measure the amount of water vapor in air in soil or in confined spaces. Bulb as the water evaporates and the wet bulb temperature becomes lower than the air dry bulb temperature.