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TECHNICAL INFORMATION SHEET NUMBER 217, Issue 1 TITLE: Using Totalizer Factors DATE: NOVEMBER 27, 2001
TECHNICAL INFORMATION SHEET NUMBER 217, Issue 1
TITLE: Using Totalizer Factors
DATE: NOVEMBER 27, 2001
AUTHOR: THOM WARREN
ISSUED BY: THE APPLICATIONS ENGINEERING DEPARTMENT
EUROTHERM CHESSELL
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Setting up totalizer factors on Chessell recorders is a simple, but often-misunderstood
process. This technical info sheet is written to help understand the terminology and how to
apply them.
For 394, 4000R, 4100G, 4103C&M, 4181G&M and 4250C Recorders
Each totalizer has two factors associated with them.
1. Period Scalar This scalar takes into account the time base of flow rate read on an
input channel per minute, per hour, or per day. The period scalar is always entered in
seconds, so for per minute flow rates, the period scalar is equal to the number of
seconds in a minute (60); for per hour flow rates, the number of seconds in an hour
(3600), and so on.
2. Unit Scalar This is a straight multiplier which allows you to change large unit
measures to small ones and vice versa in order to achieve useable resolution. If you are
totalizing an average flow rate of 1000GPM (gallons per minute) over a month, you will
end up with a very large monthly total (30days X 24hrs/day x 60mins/hr x 1000gals/min
= 43,200,000 gallons). This total is typically too large to show on the display of the
recorder. Rather than using an separate math channel to do the conversion of gallons to
millions of gallons as a unit of measurement, the unit scalar lets you do this all in one
place.
The unit scalar is equal to how many times larger or smaller your totalized units are
than the volume/mass part of your input units is. For example, for a flow rate of gallons
per hour to be totalized to million gallons, the unit of measurement, the unit scalar is
1,000,000 (10
6
). Or, going from million gallons per hour to gallons would require a
scalar of .000001 (10
-6
).
The unit scalar is also ideal for converting cubic inches per minute to a totalized value in
liters. It is known that 1 liter = 61.02 cubic inches or 0.0164 liters = 1 cubic inch.
Therefore, to convert cubic inches/min to totalized liters would require a period scalar of
60 and a unit scalar of 0.0164.
Entering Long Time Bases The period scalar is a description of the rate in seconds,
however the configuration field on the recorders only allows a four-digit entry. If you have
a rate with a long time base more than four digits would be required to describe the time in
seconds (i.e. 1 day = 86,400 seconds). In these cases, divide the period scalar by 10, 100,
1000 or other 10
x
factor to get the period scalar down to four digits. The period scalar can
then be compensated for by multiplying the number you had previously calculated for the
unit scalar in step two above, by the factor, and using the result as the new unit scalar. For
example, to totalize 100 cl per day to liters.
Period Scalar = 86,400 sec per day (24hour x 60mins/hr x 60 secs/min)
Divide by 10 to get a four-digit number: TIS-217
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Period Scalar = 8640 + a factor of 10 that will be multiplied with the unit scalar.
Unit Scalar = 100 (100cl to a liter), factoring in the 10 from above gives: Unit Scalar =
1000.
392 Totalizers Made Easy
The value of the input channel or Derived Variable (DV) is divided by the factor each second
and the result stored. Whole numbers are sent to the totalizer value as they are
accumulated. The basic factor is the number of seconds in the measurement.
Unit of Measurement examples:
Feet per second (FPS) = 1.0 sec.
Gallons per minute (GPM)= 60 sec.
Standard cubic feet per hour (SCFH)= 3600 sec.
Millions of gallons per day (MGD)= 86,400 sec.
Example: A flow of 200 GPM would have a factor of 60 (seconds). Each second at a
constant input of 100 GPM, 100/60 would be stored. At the end of 60 seconds, the totalizer
value would be 100/60 x 60 or 100 GAL.
The only difference between the 392 and the other recorder totalizers are the names for the
factor components.
392 Factors
Mantissa
Exponent
Measured Value Time Units
1.000
0.0
Per Second
6.000
1.0
Per Minute
3.600
3.0
Per Hour
8.640
4.0
Per Day
8.640
1.0
Per Day x 100