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X20 Sprayer Reference Manual
Problem 15
Rate Unstable
Information
The rate is determined from the pulses received from the Flow Meter.
These pulses are processed along with the Sprayer width, speed, and
target rate and a determination is made as to how to drive the
Regulator Valve to achieve the target rate. Most unstable rate displays
are due to erratic signals coming from the Flow Meter. With a
Centrifugal pump, air can be sucked into the pump through seals,
loose hose ttings, faulty hoses etc. This air can dramatically increase
in volume in the pump due to cavitation, and when this air pocket
passes through the Flow Meter, it will cause erratic operation, as well
as giving uctuating pressures due to poor pump efciency.
If using a Positive Displacement pump, Piston, Diaphragm etc, a
faulty valve in either the suction or pressure side will give a pulsating
ow which will also give erratic readings. If there is 5 or less pistons,
the pump will have an Accumulator (Air Pressure reservoir) that is
designed to smooth out the pulsing from the pistons. The pressure in
this accumulator is critical and should be as determined by the pump
manufacturer.
Problem 16
Rate Unstable
Information
A faulty Flow Meter can give erratic readings as well. The Flow
Meter fault can vary depending on the design of the meter. The most
common problem is wear. As the components in the Flow Meter
wear, the inpeller will move around and can drag on the side of the
housing, giving poor readings. Also, it can become jammed or sticky
due to contamination, foreign objects or poor cleaning routines. These
causes will also give incorrect volume used readings, which could be
corrected by changing the FCAL, but this only masks the problem of
a failing Flow Meter.