From the adsorption experiment has objective to study about process and result of adsorption for design an adsorption unit. From experiment use adsorbent as silica gel by adsorb water in humid air and measure the humidity at out let of adsorption column in deference time, when plotted graph between the humidity of air and time found that, firstly graph character is constant because the humidity of air is zero which mean silica gel can adsorb all of humidity of air. Then when silica gel is saturated, the humidity found at out let of adsorption column and when time pass to 2.4 minutes is the maximum value of humidity and continue constant to 3.2 minutes then the value of humidity decrease slightly that may be has errors for example silica gel before experiment has remain humidity, packed silica gel in column is not smooth and silica gel packed when it heat, so it will regenerate and water (humidity) will go out to the column. All of errors are cause of while after 3.2 minutes is not constant.
From the experiment use pack bed height 10 centimeter, when plotted graph between relative of ratio of humidity (C/C_0 ) and time found that can separate in 3 range follow characteristic of graph are range 0-2.3 minutes has humidity equal to zero, range 2.3-3.2 minutes has humidity increase slightly to C/C_0 =1 and range after 3.2 minutes has humidity decrease slightly cause from errors. The characteristic of graph is S-curve, from graph can get the value of t* (time when C/C_0 = 0.5) = 1.75 and the under area of graph mean silica gel cannot adsorb humidity anymore cause of saturation so the humidity can be detected and can calculate an equivalent length of unused bed (LUB) by LUB = L( 1 – Wb/Wsat) = 0.32 and calculate break point time equal to 1.05 , while LUB does not change with the total bed length. If the height is change to 30 centimeters the value of LUB is constant and calculate break point time equal to 1.748.