Calibration Calibration Challenge 1 A label may call
Calibration
Calibration Challenge #1 • A label may call for 1 pint of pesticide to be applied over an entire acre (1 pint per acre). • An acre is 43, 560 ft 2. (208 ¾ ft x 208 ¾ ft) • Some labels call for as little as ½ or 1/10 of an ounce of dry material (WPs) per acre. • How can this be done?
Dilution is the Solution • Its easier to spread 20 gallons of water (with 1 pint added) over 1 acre than it is to spread 1 pint by itself. • The goal……. – Find out how many gallons it takes your sprayer to cover one acre
Calibration Dilemma #2 How much pesticide do I add to the tank? • You will need to know: – How many gallons it takes your sprayer to cover one acre…. . Gallons per acre or GPA ? – How many acres you can spray with a certain volume? – What is the labeled rate of the pesticide? – Make the dose calculation (how much do I add to the tank)
Calibration Tip • Keep everything constant. • When you are field spraying, use the same speed, sprayer pressure and nozzle type as you did when you calibrated. • Keep a calibration log.
Checking your Field Speed • Set out a 200 foot course. • Drive the course at a comfortable and practical field speed. • Use this formula to double check your speed • MPH = 136. 4 Ex: 136. 4 = 5 MPH Time* 27 sec. * Time = seconds it took to drive the course
Determining GPA 3 methods • Calibration Strip Method – Preferred – Most accurate • 5940 Method • 128 th acre method
But first…. Determining GPA with a backpack or hand sprayer 18 ½ feet Measure out an 18 ½ by 18 ½ foot square in an area similar to what you will spray 1 8 ½ feet
Backpack - GPA 1. 2. 3. 4. 5. 6. • • 18 ½ x 18 ½ foot square Spray & time yourself Spray into bucket for same time and using same pressure. Collect in Ounces = GPA Why does this work? 18 ½ x 18 ½ feet = 342 ft 2 which is 128 th of an acre There are 128 ounces in a gallon
Backpack GPA Example • Sprayed calibration square and it took 45 seconds • Sprayed into bucket for 45 seconds and collected 64 ounces • GPA = 64
Calibration Strip Method • Take a small area and relate it to an acre • Need to know area of calibration test strip (in acres). One acre = 43, 560 ft 2 • Amount of liquid sprayed over strip • Remember: G---gallons applied per strip P divided by A ---acres in test strip = GALLONS PER ACRE
Calibration Strip Method Example: • Calibration strip is 66 feet x 66 feet or 4, 356 ft 2 43, 560 ft 2 = 0. 10 acres • 3 gallons applied per strip • 3 gal/strip 0. 10 acres = 30 GPA
Boom Sprayers • No matter what method of calibration is used, you need to…. – check nozzle spacing – check output across the boom.
Checking Nozzle Spacing & Height
Nozzle Orientation
Nozzle output
Checking Nozzle Output
Remember! Check Nozzle Spacing 20” Then……
Check Nozzle Output For a Given Amount of Time! (usually 1 minute) Nozzle 1 Nozzle 2 Nozzle 3 51 oz 50 oz 42 oz • Nozzle 1 = 51 oz • Nozzle 2 = 50 oz • Nozzle 3 = 42 oz 143 oz ÷ 3 = 48 oz. (average)
Checking Nozzle Output • The average of all the nozzles is 48 oz. • This is the benchmark you use to determine which nozzles need to be replaced or cleaned. • A 5% error on either side of the average is commonly used.
Calibration Tip • To find 5% – Find your average… 48 oz – Move the decimal place one space to the left. 48. = 4. 8 – – – This is a 10% error Divide by 2 = 2. 4. This is 5% error Now add 2. 4 to 48 for +5% Subtract 2. 4 from 48 for – 5% Error range = 45. 6 50. 4 Any nozzle output between 45. 6 and 50. 4 is OK!
Boom Sprayer Calibration Strip Method • Need swath width (W) x Course length (L) • Gives you sq. ft (ft 2) of the test strip • Find acreage of the test strip (test strip ft 2 43, 560 ft 2) • Find liquid applied per strip (gallons) • Use simple math Gallons applied per strip Test strip in Acres Keep going for example = GPA
Using test strip
Collect from each nozzle using test strip time. Or you can refill the sprayer and note how many gallons it took
Figure your GPA • Example: – Swath width is 35 ft – Course length is 200 ft – Calibration strip = 7, 000 ft 2 (35 x 200) – Test strip is 0. 16 acres (7000 ÷ 43560) – You collect from all the nozzles or refill the tank • 4 gallons is collected – 4 gallons ÷ 0. 16 acres = 25 acres
Broadjet 0. 5 g in 13 sec. 100 3400 = 0. 078 acres 43560 34 0. 5 g 0. 078 acres = 6. 4 GPA
5940 Method • Based on nozzle output within 5% of the average. • Not only gives you GPA but also how much you need to collect from under each nozzle to reach a desired GPA. • Uses the following basic formula:
GPA = GPM X 5940 MPH X W • GPA = Gallons Per Acre • GPM = Gallons per Minute collected from a single nozzle (Make sure all nozzle are within a 5% range. ) • 5940 is a constant • MPH = Field Speed • W = 1) width between nozzles or 2) width of a broadjet swath in inches.
5940 Example • You have checked all your nozzles and the average is 64 ounces per minute (OPM). All nozzles are within 5% of this average. • 64 OPM = 0. 5 GPM (64 ounces ÷ 128 oz. /gallon) • Your field speed is 5 MPH • Your nozzles are spaced 20” apart GPA = GPM X 5940 = 0. 5 GPM x 5940 = 2970 MPH X W 5 MPH x 20 100 GPA = 29. 70 or 30 GPA
Using 5940 to find out how much you need to collect to get a certain GPA! • Rearrange the basic formula to look like this: GPM = GPA x MPH x W 5940
5940 Example #2 • You want to apply 20 GPA. Your broadjet has a swath of 35 feet. Your field speed is 5 MPH GPM = GPA x MPH x W 5940 20 GPA x 5 MPH x 420 (35 ft x 12”) 5940 7 GPM = 42, 000 5940 You need to collect 7 GPM to get 20 GPA
Boom Sprayer GPA 128 th Acre Method • • Measure distance between nozzles. Use chart for test course distance. Nozzle output must be close to uniform Ounces collected from one nozzle = GPA Nozzle spacing (in. ) Test Strip (ft) 20 30 36 38 40 204 * 136 113 107 102 *340 ÷ spacing (ft)
Broadjet -= 128 th Acre Method • Measure swath width • Set calibration course Swath width Course length 35 156 * *5460 ÷ W (ft) 40 136 45 121 • Time yourself • Collect for same time • Pints collected = GPA
Boom Output and GPA Using the 128 th method you get: 15 ounces = 15 GPA Check the label May be too low.
How many acres can you spray. Volume used GPA = Acres
How many acres can you spray - Example • Have a 1000 gallon tank. Only want to apply 500 gallons. • GPA = 25 • 500 gallons = 20 acres 25 GPA • Backpack 5 gallons = 0. 078 acres 64 GPA
Acres - Example 2 • Suppose you only want to spray 10 acres. • GPA = 25 (25 GPA) • Now just back-multiply…. Gallons? ? ? = 10 acres 25 GPA • 25 GPA x 10 acres = 250 gallons of total mix is needed (pesticide and water)
Dosage Determination • Listed rate per acre …Read the label • Lbs. of a. i. per acre – Liquid – % W. P.
Listed Rate Per Acre • Acres x labeled rate = dose • 10 acres x 1 pint/acre = 10 pints in a given volume – 300 gallon mix = 10 acres 30 GPA – 10 acres x 1 pint/acre = 10 pints – 10 pints of product to make a 300 gallon mix.
Pounds per Acre - Liquid Example – 1 lb of a. i. is recommended per acre 1 gal. Formulation x 1 lb a. i 2 lb a. i. Acre = 0. 5 x 1 = 0. 5 gal formulation/acre Rate = Lbs. a. i. /gallon = 1 2 0. 5 gallons formulation/acre
Dry Formulations • 2 lbs per acre of an 80% WP is prescribed 1 lb formulation 0. 80 lb a. i. x 2 lb a. i. Acre Rate per acre = % a. i. 2 lb a. i. 0. 80 = = 2. 5 lbs formulation/acre 2. 5 lbs
How much product to add to tank. • Rate/acres x acres treated • Example: 1 pt/acre x 10 acres = 10 pints. • Backpack 0. 078 acres x 16 oz. = 1. 2 oz.
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