AW Gear Meters RT-Ex15-Ex - Manual (Page 11)

AW-Lake Company 8809 Industrial Drive, Franksville, WI 53126  web: www.awgearmeters.com
 Tel: 262-884-9800  Fax: 262-884-9810  Email: [email protected]
RT-Ex15-Ex manual rev 6.13.11.docx Revision 3.3.10
11
RATE Mode Programming
The Rate parameters are programmed from the RATE A
GT or RATE A PL display screen. RATE
A PL variables can also be programmed from the RATE A GT screen or vice versa by toggling to
the RATE A
PL
mode using the SEL button or magnetic switch. Use the MODE/DN button or
magnetic switch to select the RATE GT display. Press and hold the ENT button or maintain the
ENT magnetic switch. The display will first show a P in the lower left-hand corner and will then
display the first program variable for that rate display mode. Three parameters will be accessed
for either mode as follows:
RATE A
GT RATE A PL
 KFR A VALUE  KFR A VALUE
 GATE A B  SAMPLE A
 ENG UNITS A  ENG UNITS A
KFR A VALUE – Scaling factor to display rate in a desired engineering unit such as GPM. The
KFR factor entered here will also determine the decimal resolution of the rate display. The KFR
is calculated using the K-factor of the transducer being monitored. The K-factor is the number
of impulses per engineering unit established by the transducer manufacturer or by a calibration
test. The K-factor and recommended KFR values are given on the AW-Lake Calibration sheet.
Initial default is 100.00 (Displays Hertz w/ two decimal places)
The KFR factor is calculated using the following formula:
KFR= Time Base Constant/K-FACTOR
Where:
- 100 is the time base constant for eng. units per second
- 6000 is the time base constant for eng. units per minute
- 360000 is the time base constant for eng. units per hour
- 8640000 is the time base constant for eng. units per day
- K-FACTOR is the average number of pulses per desired
eng. unit that the transducer produces.
Determine the number of decimal places desired for rate display, round off the result of the
formula to the desired accuracy and enter the KFR using only that number of decimal places.
Using too few decimal places can cause relatively large display errors up to several percent of
actual reading. Using too many decimal places can result in displays with a level of precision
exceeding the accuracy of the meter. It is recommended to use no more than four digits
regardless of decimal point position! The largest acceptable value for KFR is 65535 with the
decimal in any location.
For example:
A flow meter has a K-factor 2053.57 imp/Gal and the display should read in Gal/Min.
with accuracy to three decimal places.
KFR = 6000 / 2053.57 = 2.921741 for GPM
Round off 2.921741 to three decimal places and enter 2.922 for KFR.