Hardware manual

Chapter 2 - TeleFlow Standard ACCOL Load
TeleFlow™ Standard ACCOL Load
2-8
the total cleared for the next period. The running total is not cleared; it accumulates
to 10 million at which point it rolls over to zero and continues accumulating.
Averaged Extension
The average value of the Extension ( square root of the product of process DP and
absolute Static Pressure) is computed for each log period (hour or 15 min) and for
the day and saved in an archive. This average is maintained separately from the
value used in calculating the flow volume for a Calculation interval.
Back Flow
The time spent in a Back Flow condition is totaled for the current and previous day
and an alarm is generated if the condition exceeds a user-specified limit. As each
input sample is processed, the DP reading is examined to see if a Back Flow
condition is present.; (i.e. DP is less than 0.0 and the absolute value of DP is greater
than the DP Cutoff). If a Back Flow condition is detected, a Back Flow timer is
started. If the Back Flow condition remains in effect for a user configured number
of seconds, a Logical Alarm signal is turned 'ON'.
The amount of time during which a Back Flow condition has been detected for the
current day is accumulated in an Analog signal. At the end of the contract day, the
value in this signal is transferred into the previous day's Back Flow Time signal
and the signal is set to 0.0. All intervals of Back Flow are accumulated,
independent of the alarm state. (i.e. Short durations of Back Flow, less than the
Back Flow timer, are accumulated even though the Back Flow Alarm is not turned
'ON'.)
Gas Energy Calculations
Gas flow volume for a Calculation interval is converted to energy in MMBTU (i.e.
DekaTherms; a DekaTherm is 10 million Btu) by multiplying by a Heating value in
BTU/cu.ft. and dividing by 10 million; the Heating value can come from a fixed
value or from an AGA5 calculation.
The energy for the interval is summed to produce an energy total in MMBTU for
the each hour and day, and for the current month.
Flow rate is converted to energy rate in MMBTU/hr.