28
third line below C+D % ms in the Pulsator
Ratio function. B Fluc is displayed in either
“Hg or kPa and is the amount of fluctuation
during the B Phase of the pulsation wave
as calculated by the Pulsator Ratio.
The B phase of the Pulsator Ratio is the
phase which corresponds to the open and/
or milk phase. The B Fluc parameter is
intended to give an indication of movement
within the top portion of the B phase,
which would ideally be straight. Since, the
B phase begins at 1.2” Hg below
Maximum vacuum on the upwards slope of
the curve and continues to 1.2” Hg below
Maximum vacuum on the downwards
slope, the end points of the B phase are
excluded from evaluation in the B Fluc
parameter. Technically, 1/16 of the B
phase at both the beginning and the end of
the phase are not included in the B Fluc
calculation. Therefore, 87.5% of the B
phase is evaluated, with the difference
between the maximum level and minimum
level during that period outputted as B
Fluc.
Milk/Rest Ratio
The Milk/Rest ratio is the ratio of the time
when the teat cup liner is not collapsed
(Milk) to when it is collapsed (Rest).
Collapse of the liner is based on the
differential of a pulsating vacuum (vacuum
and atmospheric air) on the outside of the
liner, between teat cup and liner, and a
(relatively) steady vacuum on the inside of
the liner.
The point on the pulsation curve at which
the liner collapses should be determined
by the user. This is a simple and
straightforward calculation:
A. Determine the average vacuum at teat
end using the DIGIMET 3000 with its
Vacuum Level Function.
B. Determining the differential pressure
required to collapse the liner needs to be
determined. The differential pressure
required to collapse the liner is generally:
1) specified by the liner manufacturer; 2)
specified by other sources; 3) determined
by a simple test; or 4) determined using
several rules of thumb:
RULES OF THUMB: Thin-walled liners, on
the average, require a differential pressure
of 2" Hg in order to collapse. Medium-
walled liners require, on the average, 5"
Hg of differential pressure to collapse.
Thick-walled liners need, on the average,
7" Hg of differential pressure to collapse.
Based on the two values found in A and B,
a point referred to as the Liner Collapse
Point (LCP) is determined:
LCP = Average Vacuum - Differential
Pressure to collapse liner
The DIGIMET 3000 allows LCP selection
by the user; any average vacuum and liner
differential pressure combination can be
accommodated (see Liner Collapse Point
in the Utility Menu section).
To calculate the M/R ratio, the current
input sample is compared against the
currently set LCP. If the input vacuum is
greater than or equal to the LCP, the
pulsator is in the Milk phase; otherwise, it
is in the Rest phase.
The following calculations are made:
Total Time = Milk Time + Rest Time
Ratio Milk = Milk Time / Total Time *
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