|Vector and Pest Control in Refugee Situations (United Nations High Commissioner for Refugees (UNHCR) / Alto Comisionado de Naciones Unidas para los Refugiados (ACNUR), 1997, 124 p.)|
In order to prepare a suspension or a solution from a given formulation of a pesticide in wettable powder or emulsifiable concentrate form, the following formula must be applied:
X = quantity of formulation necessary
A = desired concentration
B = desired quantity of solution
C = concentration of a.i. in the formulation
D = 1 if X and B are expressed in kg or litres; D=8.33 if X and B are expressed in pounds or US gallons and D=10 if X and B are expressed in pounds or imperial (UK) gallons.
To obtain 100 litres of a 2.5% solution from an insecticide formulation containing 50% a.i.:
Therefore 5 kg or 5 litres of insecticide formulation have to be mixed with 100 litres of water to obtain the solution at the concentration required for filling the pumps.
N.B. When using powders for suspensions, the powder should be put into a receptacle with a little water, and mixed to obtain a paste. This paste should then be thinned by adding small quantities of water until the desired volume is attained and the resulting mixture poured through a filter into the tank.