Hi guys,

The experiment I am setting is to test the impact of variations in atmospheric temperatures on the hydrologic behavior of 5 types of Permeable Pavement Systems (Drainage, Detention , Evaporation) at different atmospheric temperatures ( 32 F, 56F, 86F): I have these problems :

1- Evaporation :
a-    How can I eliminate the interference of Relative humidity from the                      experiment I am conducting, I will be using an exhaust  fan to encourage the evaporation in the lab, but I dont want to have different rellative humidities at the temperatures at which I am conducting my experiment    ?

b- I will be measuring daily evaporation by weighing  the samples every day , the difference of the readings  will be assumed to be the evaporated amount. bt the problem, how can I weigh 150 Kg (330 Ib) sample with a precision of (1-5 grams), since evaporation will be occuring in small amounts, a s expected 10 grams will be evaporated daily, so how can I measure this amount ? – I dont have enough budget to buy high precision balance, even so, it will be difficult to find a balance with  330 ib capacitiy having a precision of 1 gram ?

Thank you in advance !