Liquid Controls SP2200 - Manual (Page 13)

11
CALCULATING SCALE FACTORS
There are two separate dividing scale factors, one for input "A" and one for input "B". The factor to enter is the number of
pulses per the desired unit of measurement. The factor ranges from 0.0001 to 99999. The factor is the same for rate and
count. Because the "units per second", "minute", or "hour" are field programmable from the keypad, scale factor calcula-
tions for the ratemeter are easy. Here are some examples:
SCALING FACTOR EXAMPLES:
UNIT COUNTING:
You pick up a notch on a paper roll (1 pulse per shaft revolution). Each revolution equals 3 feet. To
find the number of pulses per foot, simply divide "1 pulse" by "3 feet" (1
÷
3 = .3333).
Solution - One foot equals 0.3333 pulses, enter this as the scale factor and the display will read in
feet.
RATE:
A conveyor carrying bottles must be controlled for bottle speed. For each revolution of the front roller, three bottles
travel by. Thus, one revolution equals 3 bottles. A wheel with seven spokes is mounted on the roller. The user
can't sense bottles because they are traveling through a washer, so a sensor is placed at the roller, sensing seven
pulse per revolution of the shaft, which equals 3 bottles per revolution.
To calculate the scale factor (7 ppr
÷
3 bottles) = 2.3333 scale divider. Set rate per second, minute or hour as
desired.
FLOW IN LITERS:
A flow meter is generating 52.6 pulses per gallon. The desired readout is in liters. Since there are 3.785 liters per
gallon, divide 52.6 by 3.785 to find the number of pulses per liter (52.6
÷
3.785 = 13.897).
Enter 13.789 as the scale factor so the display will read in liters.
CUT TO LENGTH:
An aluminum sheeting plant has a cut to length application to customer specification. A 100 pulse per revolution
encoder with a 12" wheel is used to sense. The travel of aluminum sheets is in 0.1 inches. Thus, after 100 pulses,
you want 12.0 to appear on the display. Note that decimal point is for display only. Factor must be calculated to
show all desired units of measure. Thus, 100
÷
120 (total desired units of measure) = 0.8333. Enter 0.8333 as your
scale factor. Set “dummy”decimal point location to 0.0 under Program Count section.
FLOW BOILER OR MOTOR “A-B”:
Fuel usage of a boiler can be monitored using the “A-B” option. Separate factors can be entered for Factors “A”
and “B”, but the time base must be the same for rate.