Stacker Row-to-Row Accuracy

There is simply no point in applying liquids in-furrow unless you do it accurately! “Under apply product and you’re ineffective, over apply product and you’re wasting money, fracture you streams and you can forget about applying fungicides and inoculants via injection”.

Apart from being absolutely essential that a system is capable of true and verifiable rate control, its allied distribution system must equally be capable of delivering liquid at the openers evenly and precisely on a second by second basis. The accuracy of a system is determined by its COV (Coefficient of Variation) - the lower the COV, the more accurate the system.

There is only one rule and it is King and unless you can alter physics it always has, and always will apply to the flow and control of liquids. “Liquid will always follow the path of least resistance”.

A good distribution system must have the best (lowest) COV possible, peripheral stream control (stream control at the openers) and minimal time lag (shut down/start up) at the openers. Such a standard of control can only be achieved by minimising variables within a system. Avoid components that induce hysteresis or that have variable behaviour. “Hysteresis is where there is a lag in response to a change of input”. Remember that a variation of just 6/1000”  (eg. 22/1000” – 28/1000”) in  control devices can result in a 60% variation in output at 29psi (2.0 bar).

Many claims emerge from proponents of variable mechanical devices and principal among these is “our devices automatically cover all rate ranges”. What they will not tell you is how accurately they apply product across the tool, outlet by outlet, second by second – at the openers! When confronted by claims like these ask the proponent to provide verified data including the system COV.  If they can’t provide verifiable data, start to worry.

Our systems are the result of 10 years continuous development. We design and manufacture our own components in accord with data gleaned from extensive field and laboratory testing. This has enabled us to provide systems to the industry that have a verified average COV of 4.1% over an operating pressure range of 0.3bar – 7.0bar (4.5psi – 100psi).*

The chart shown compares the Coefficient of Variation (COV) of the Liquid Systems (SA) STACKER Distribution system against a commonly used variable flow system. COV is a measure of how evenly liquid is applied across the bar. The lower the COV the more even the distribution.

The results demonstrate an extreme contrast in accuracy between the two, especially at lower rates. The STACKER Distribution provides far superior performance. This test was an independently controlled and conducted by a US customer.

Study these independently verified COV performance charts and compare our system with a variable system. The top chart is at 30” spacings. The bottom chart is at 12” spacings. The results may shock you!