Smithco Turf Spraying Guide - Manual (Page 14)

5. Tee-Jet 844 Computer
One of two new controllers offered by
Spraying Systems, this is the simple
computer by Tee-Jet. Complete weather
proofing and non-volatile memory are two
very important points that will register with
your customers immediately. It can monitor
either flow or pressure (using a flow meter
or pressure transducer), but not both at the
same time. It displays all the sprayer
information on a single screen; target rate,
speed, pressure (calculated) volume
sprayed and area covered. Very effective
as a flow based controller, it has a unique
system for programming application rates.
Designed with essentially a tip chart
programmed into its memory, when
entering your gallons per acre (or gallons
per thousand) it will tell you the speed and
pressure required with the tip selected. The
program will always default to the speed for forty PSI, and as you adjust speed it will change the
required pressure. If you are unable to achieve the balance you want, changing the tip size on the
computer will bring the parameters into a workable range. The 844 allows an operator to do “what ifs”
before mixing chemical. Additionally, information from a spraying event can be downloaded to either an
optional printer or directly to a computer. The 844 is also GPS capable, but that technology is off in the
future for turf.
6. Tee-Jet 855 Computer
The more sophisticated controller from Spraying Systems, the 855 monitors both flow and pressure,
using one as a primary and the other as a
backup and also features the weather proof
housing and non-volatile memory. Again, flow
based is recommended for the aforementioned
reason. This enables the 855 to perform some
very neat tricks, which will be explained a little
later. The 855 has two screens for reading out
information; the left one showing speed, target
rate and pressure while the right displays actual
rate (being applied), volume applied and acreage
covered. Repeatedly pressing a button changes
each display and LEDs illuminate to tell the
operator which mode is currently being displayed.
It will store up to four preset rates, and each rate
can be overridden by plus or minus increments,
up to a maximum of ninety percent either way
(tips being the real limiting factor). When
programming application rates, extensive tip
information is entered into the computer. For each rate, tip size, minimum/maximum recommended
operating pressures and tip spacing is also required. The information plus the dual monitoring is what
lets the 855 do it special tricks. It will alert the operator when pressure falls below minimum by flashing
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