Determination of RH% TTQC Lab by Wet and Dry bulb Hygrometer.

Experiment No: 01

Experiment Name: Determination of RH% TTQC Lab by Wet and Dry bulb Hygrometer.

Introduction:

Humidity: Humidity is the term used to describe the moisture existing in the atmosphere.

Relative Humidity: The amount of water vapor in the air at any given time is usually less than that required to saturate the air.

The actual vapor pressure ratio to standard vapor pressure ratio at the same temperature defines as the percentage is called relative humidity.

Relative humidity =  Actual amount of water vapor in air/Standard amount the air can hold at that temperature *100%

Objectives:

(1) To maintain atmospheric condition of testing laboratory.

(2) To obtain good efficiency in work place.

(3) To know about dry and wet bulb hygrometer.

(4) To maintain physical properties of the fiber.

Machine description:

A hygrometer is an instrument used for measuring the moisture content in the atmosphere. It consists of two bulb called dry bulb and wet bulb. A muslin sleeve is attached with the bottom of wet bulb. There is a place in the bottom of the hygrometer where water box can be attached. One end of the muslin sleeve s attached with the wet bulb and the other end is inserted inside the water box which contains distilled water.

Working principle:

(1) At first we will take the reading from the hygrometer.

(2) Then we will calculate the difference of the dry and wet bulb reading.

(3) Then we will take the value of relative humidity from the chart.

(4) We will take the reading of the dry and wet bulb 5 times at a interval of 15 minutes.

(5) After taking 5 reading we will calculate the average of RH%.

Table:

Observation no.	Time	Dry bulb temp.	Wet bulb temp.	Difference	RH%	Average
1.	12:10 – 12:40	24	19	5	60
2.	12:40 – 12:55	23	18	5	59
3.	12:55 – 1:10	24	19	5	60	59.6
4.	1:10 – 1:25	24	19	5	60
5.	1:25 – 1:40	23	18	5	59

Table calculation:

1^st reading: Dry bulb temperature = 24⁰ C.

Wet bulb temperature = 19⁰ C.

Difference = (24 – 19)⁰ C.

= 5⁰ C.

2^nd reading: Dry bulb temperature = 23⁰ C.

Wet bulb temperature = 18⁰ C.

Difference = (23 – 18)⁰ C.

= 5⁰ C.

Similarly 3^rd, 4^th, 5^th difference 5⁰ C.

RH% Average = 59.6 %.

Result:

The average RH% is 59.6%. The desired RH% is 65±2⁰ C. To get the denied RH% we have to spray water vapor in the textile laboratory.