SANDPIPER RuppTech Stroke Counter/Batch Control - Manual (Page 3)

Batch Control/Stroke Counter Page 3 Batch-sc-rev0611 520-180-000 3/02 Batch Control / Stroke Counter Page 3
Programming for Accuracy
To preset accurate batch programs, it is important to know actual system
performance. Gather this information by measuring output volumes gener-
ated by test runs of the systems, using published pump performance as
a starting program. Careful measurement will tell you how much volume
your system is actually discharging on every stroke. You can then adjust
the program accordingly. Here is an example.
EXAMPLE OF USE:
A product is blended based on incoming orders. Two ingredients are
mixed in a ratio of 3 to 1, creating the final product.
Order volumes are typically 50, 500, 1000, 1500 and 2000 gallons. Two
pumps transfer the ingredients to a mixing area for “batching”.
Pump #1 in this example is the transfer pump for the main element. Its
control has Preset Counts set as follows:
Pump #1 Preset Counts:......... PO - 37.5 gallons ..... P1 - 375 gallons
................................................ P2 - 750 gallons ....... P3 - 1125 gallons.
................................................ P4 - 1500 gallons
Stroke Scale Valve: ................. 0.34 gallons per stroke
The control’s Stroke Scale Value is set at the displacement per stroke of
the 1½-inch pump to which it is connected, .34 gallons.
Pump #2 in this example is the transfer pump for the second element.
Its control has Preset Counts set as follows, based on the 3 to 1 mixing
ratio:
Pump #2 Preset Counts:......... PO - 12.5 gallons ..... P1 - 125 gallons
................................................ P2 - 250 gallons ....... P3 - 375 gallons
................................................ P4 - 500 gallons
Stroke Scale Valve: ................. 0.09 gallons per stroke
Pump #2’s control has the Stroke Scale Value set at the displacement
per stroke of the 1 -inch pump to which it is connected, .09 gallons.
Though each pump requires its own control unit, both controls can be
tied together with one remote Start/Stop switch running both units.
TESTING THE SYSTEM
Since each control gets one pulse or signal
from its pump for each stroke, the volumes
referenced in the example should be set for the
closest total volume available.
For example:
Pump #1.............P1 - 375 gallons @
............................0.34 gal. per stroke
............................= 1102.94 strokes
Adjusting for 1103 strokes would deliver
375.02 gallons, assuming 100% efficiency from
pump and system. Realistic expectations of a
well-designed and implemented system fall in
the range of 1% to 3%.
Based on data obtained from the system,
it becomes evident where the system will
perform from an accuracy and efficiency
standpoint. This will indicate adjustments to
be made.
For example:
Testing showed in the example system
that Pump #1 delivered 363.93 gallons, within
the 3% range of accuracy. Since the Stroke
Scale Value was set at .34 gallons per stroke,
1103 strokes actually produced .329 gallons
per stroke.
Formula is:
Flow ÷ Strokes = Gallons per Stroke
363.93 ÷ 1103 = 0.329 gal./stroke
This test indicates the system should be
reset to produce a total flow closer to the batch
target of 375 gallons.
Formula is:
Batch Target ÷ Gal. per Stroke = # Strokes
375 ÷ 0.329 = 1139.81
Rounded to 1140 strokes
The controller cannot count a fractional
stroke, so the number of strokes is rounded
to the nearest whole number, 1140. This gets
closer to the target batch size of 375 gallons,
actually producing 375.06 gallons.
The same type of testing, calculation and
adjustment would be applied to all pumps in
a system. Each pump’s performance will be
effected by the application and system
in total.
WHERE TO FIND PUBLISHED PUMP
PERFORMANCE
Published pump performance is found on the data sheet
issued for model pump. Displacement is shown to the right
of the performance curve.
If you do not have the appropriate data sheet, contact your
local Warren Rupp or Marathon distributor for a copy. Or
you can contact the Factory Literature Department at the
number shown below.
To receive the correct sheet, be sure to verify the pump
model and type, which is shown on the pump nameplate.