# calibration

Discussion in 'Pesticide & Herbicide Application' started by bradyard, Feb 13, 2009.

1. ### bradyardLawnSite Memberfrom ArkansasMessages: 6

I'm in the golf course industry, looking to get in residential weed control.
I've only been around boom sprayers. How do I calibrate a skid sprayer with hose and a shower nozzle?

Find out from your spray chemical supplier what volume of liquid you wish to apply per unit either measured in gallon/1000 sq. ft or litres/100 sq. meters. Call this V

Measure off an area of lawn that is exactly 1000 sq. ft or 100 sq. meters. Use unit compatible with those obtained in step 1.

Measure the amount of time it takes to spray the area designated in step 2 in seconds. Call the number of seconds it takes T

Calculate the flow rate F required out of your gun using the following formula:

F=Vx(60/T)

Find F in chart above (for TK nozzles), which will give the required nozzle and pressure to spray at with that nozzle. You will notice that two or more nozzles will often give the same flow rate at different pressures. Keep in mind that if a lower pressure is used, the resulting droplet size produced will be larger and therefore drift and evaporation will be reduced.

Obtain the actual flow rate for the nozzle by testing it using a nozzle pressure gauge and graduated cylinder in the following procedure.

Fill tank with clean water (10 or 20 gallons will do)
Install nozzle pressure gauge between nozzle and end of gun.
While the gun is open and spraying, adjust the pressure at the pressure regulator until nozzle pressure gauge reads required pressure being that pressure obtained from chart in step 5
Note that pressure reading on the gauge located at the pressure regulator (this should be higher than the nozzle pressure) Maintain this pressure at the regulator between calibrations of the sprayer in order that the nozzle pressure may be in close approximation of the pressure required as indicated by the chart in step 5.
Measure the amount of time required to fill graduated cylinder to 1 litre mark to the nearest second giving TF
Use one of the following formulas to calculate the actual gallons/minute or litres/minute flowing from the nozzle.

3. ### cod8825LawnSite Senior Memberfrom Kansas City, MOMessages: 501

Couldn't have said it better myself. I am younger so I can do this when I was trained they told me to apply two gallons per 1000 sq ft and spray 1000 ft a minute. I've been doing it this way for three years and am still doing it.