understanding injectors and fertilizer ratios

Understanding Injectors and Fertilizer Ratios

Steven E. Newman, Ph.D., A.A.F.Greenhouse Crops Extension Specialist and Professor of FloricultureColorado State University Extension

2ProGreen EXPO 2010

Fertilizer Concentrate

How Fertilizer Injectors WorkInjectors are mechanical

devices that take a small amount of a concentrated chemical from a stock tank and introduce it to a water line for delivery

Injectors are ideal for applyingWater soluble fertilizers, Pesticides, Plant growth regulators,Wetting agents,Disinfectants, andMineral Acids

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Clear water Diluted fertilizer

To plants

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How Fertilizer Injectors Work• One part of stock solution is

mixed with “x” parts of water in the waterline, where “x” is determined by the injector ratio.

• The size of the stock tank can vary from as small as 5 gallons to as large as 2,000 gallons.

• A 5-gallon stock tank used with a 1:100 injector ratio will yield 500 gallons of final solution.

• Often, injector ratios are expressed as a percentage.

Injector ratios expressed as percentages• 1:50 = 2%• 1:100 = 1%• 1:200 = 0.5%• 1:500 = 0.2%

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How Fertilizer Injectors Work

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100 parts toplants

1 part fertilizer concentrate

99 parts water

Injector ratio1:100

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How Fertilizer Injectors Work

Types of Injectors• Venturi Injectors– Hozon and Syphonex

• Positive Displacement Injectors– Dosotron– DosMatic– Anderson– Smith– Gewa

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Venturi Injectors

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Simplistic No moving parts Inject at a constant rate Inexpensive Uses pressure created

between the waterline and the stock tank to draw concentrated fertilizer into the hose connection from the vacuum line

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Venturi Injectors

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Venturi Injectors

• Venturi designs– Simplistic– No moving parts– Inject at a constant rate– Inexpensive

• Siphon Hose– 16:1 Ratio – Dispenses fertilizers as

well as other pesticides

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Venturi Fertilizer Injectors

Pros• Simple with no moving

parts• Inexpensive• Flexible for many

chemicals including wettable powders

• Portable

Cons• Back pressure can stop

siphon (check valve)• Unit should not be

further than 50 feet from hose end

• Reduction in water pressure and flow

• Minimum 35 psi water pressure

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Positive Displacement Injectors• Consistent injector ratios over

a wide range of water pressures and flow rates

• Many models use water pressure as the power source

• Injector ratios can often be adjusted while in use

• The limiting factor is the minimum and maximum flow rates permissible

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Positive Displacement Injectors

• Smith Measuremix– Water driven pump– Cast metal and stainless

steel construction– Injector ratios are

factory set at 1:100, or 1:200

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• Smith Measuremix– Water driven pump– Cast metal and stainless

steel construction– Injector ratios are factory

set at 1:100, or 1:200– Some models have dual

heads for simultaneous injection of different chemicals

– Repairs are expensive and the units are heavy


• Dosatron / DosMatic– Water driven– Polymer construction– Typically installed

directly in the water line




• Dosatron / DosMatic– Water driven– Polymer construction– Typically installed

directly in the water line– Multiple units for dual

injection of different chemicals


• Dosatron / DosMatic– Simultaneously inject

products that may not be compatible in a stock solution

– May be easier to install inexpensive injectors in-line

– Multi-head systems for greater volumes of water



• Anderson Ratio:Feeder– water driven– cast metal construction– polymer construction– module injection heads



• Positive Displacement Pump Proportioner– water driven– cast metal construction– polymer construction– module injection heads

• metering device




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Mixing Tank

Water Motor

InjectorHead

FertilizerStockTank

Water flow in

Water/Fertilizerflow out

pH and EC electrodes

Anderson Ratio:Feeders can be automated with sensors and a computer to regulate fertilizer ratios.


• Positive Displacement Pump Proportioner– water driven– cast metal construction– polymer construction– module injection heads

• metering device• electronic control



Positive Displacement InjectorsGewa Injector

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PolybutyleneBladder with

FertilizerConcentrate

Flow in Flow out

Wat

er p

ress

ure

Wat

er p

ress

ure


Which injector is best for you?• Size of your operation

– Greenhouses up to 10,000 square feet are easily serviced with small units

– Larger greenhouses may want to consider a more permanent installation

• Types of fertility programs– Different crops may have different

fertility regimens– Consider future expansion

• Water flow rates• Injector ratios

– Fixed ratio injectors– Variable ratio injectors

• Water pressure• Water quality• Stock tank size

– At least large enough to satisfy daily irrigation needs

– May need two separate tanks– Opaque to sunlight– Make sure that the stock tank is

lower than the injector to prevent back siphoning

• Chemicals being injected• Portable or stationary• Ease of repair, parts availability,

longevity• Manufacturer’s support

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Positive Displacement Injectorsopen/closed

clos

ed/o

pen

Chec

k va

lve

Parallel

Series

Bypass Permanently installed injectors may be plumbed off the main water line in several configurations.

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Chemicals to be injected

Acid injection Backflow protection

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Filtration

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Water hammer

• Many injectors are made of ABS plastic

• Over time these may become brittle

• ¼ - turn valves increase water hammer

• Water hammer arrestors will prolong the life of your injector

• Place the arrestor between your valve and your injector (outlet side)

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Water hammer is the energy that is in water traveling in one direction. When a valve abruptly closes, the ricocheting water increases up to four times the original pressure.


Calibrating an Injector

• Injectors are mechanical devices that require periodic checks and adjustments.

• There are two means of checking the calibration of an injector– Volume ratio method– Electrical conductivity

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Volume Ratio Calibration Method• Equipment

– Graduated cylinder• One or two liter is best

– Large container with a known volume• Five gallon bucket

– Injector with hoses and tubes

• Procedure– Place the siphon tube into the

graduated cylinder and operate the water and injector at a normal pressure

– Allow the system to empty one volume of the graduated cylinder to charge the system

– Refill the graduated cylinder and run the injector until the cylinder is half empty

– Discharge the water from the injector into the large bucket.

– Measure the uptake volume and the discharge volume

– The injector equals the output volume divided by the input volume

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Injector ratio = output volume ÷ input volume


Injector ratio = output volume ÷ input volume

1:50

370 ml

5 gallonsor

18,925 ml

18,925 ÷ 370 = 511:51


Calculating Parts per Million• Most greenhouse fertilization

recommendations are based on parts per million or ppm

• Most manufacturers provide tables for easy reference, but they are not necessary.

• With a little knowledge, a calculator, and some patience, you can do this on your own.

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Quick 75 Formula1. To calculate the amount of

fertilizer required,2. divide the desired ppm by 75 and 3. then divide by the decimal fraction

of the desired nutrient (such as nitrogen, potassium or phosphorous) contained in the fertilizer.

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Quick 75 Formula1. To calculate the amount of

fertilizer required,2. divide the desired ppm by 75 and 3. then divide by the decimal fraction

of the desired nutrient (such as nitrogen, potassium or phosphorous) contained in the fertilizer.

4. This results in the number of ounces of fertilizer to use in 100 gallons of water.

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Confused?

Some examples of what one part per million represents under various conditions are:o 1 crystal of salt in 5 lbs., o 1 drop in 16 gallons, o 1 inch in 158 miles, o 1 minute in 1.9 years, o 1 pound in 500 tons, ando 1 cent in $10,000.

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Confused?

Some examples of what one part per million represents under various conditions are:o 1 crystal of salt in 5 lbs., o 1 drop in 16 gallons, o 1 inch in 158 miles, o 1 minute in 1.9 years, o 1 pound in 500 tons, ando 1 cent in $10,000.

To calculate ppm in 100 gallons of water,1. First multiply 100 gallons by 8.34 pounds

per gallon which equals 834 pounds. 2. Multiply 834 pounds by 16 ounces per

pound which equals 13,344 ounces per 100 gallons.

3. Therefore, 13,344 ounces per 13,344,000,000 ounces equals 1 part per million,

4. or more simply 0.013344 ounces per 100 gallons of water equals 1 PPM.

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ppm Revealed1. 100 gal. * 8.34 lbs./gal. = 834 lbs. 2. 834 lbs. * 16 oz/lb. = 13,344 oz. 3. 3,344 oz/100 gal. 4. 13,344 oz./13,344,000,000 oz. = 1 PPM 5. 0.013344 oz./100 gal. = 1 PPM

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The next step is to multiply the desired PPM by 0.013344, which is 74.94.

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Putting the Formula to Use1. Assume that the fertilizer recommendation calls for 200 ppm of nitrogen

from ammonium nitrate (33% N)2. Using the Quick 75 equation,

1. divide 200 ppm by 75 resulting in 2.67,2. and then divide by 0.33.

3. The answer is 8.09 ounces of ammonium nitrate which dissolved in 100 gallons of water will yield 200 ppm nitrogen.

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Relate the Quick 75 to an Injector

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100 parts toplants


99 parts water

Injector ratio1:100




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Clear water Diluted fertilizerInjector ratio1:100

50 gallons




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1 part fertilizer concentrateX 50 gallons

50 gallons of concentrate delivered

99 parts waterX 50 gallons

4,950 gallons of water

Injector ratio1:100




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1 part fertilizer concentrateX 50 gallons

50 gallons of concentrate delivered

99 parts waterX 50 gallons

4,950 gallons of water

Injector ratio1:100

4,950 + 50 = 5,000 gallons




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100 parts toplants99 parts water

Injector ratio1:100



50 gallonsFertilizer Concentrate


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5,000 gallons to plants4,950 gallons water

Injector ratio1:100

404.5 ounces or 25.3 pounds of ammonium nitrate

dissolved in 50 gallons of water


Still want a table?

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For more information, contact me athttp://ghex.colostate.edu/http://www.twitter.com/newman7118http://twitpic.com/photos/newman7118http://www.facebook.com/senewmanhttp://ghadvisor.blogspot.comhttp://www.linkedin.com/in/[email protected]@colostate.eduAnd….. (970) 491-7118


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http://ghadvisor.blogspot.com/

http://www.linkedin.com/in/snewman7118

mailto:[email protected]

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