FloBoss 503 and 504 Instruction Manual
Rev 04/04 General Information 1-9
1.4.2.2 Flow Calculations for Turbine Metering
The turbine flow calculation is in accordance both with 1996 AGA Report No. 7 (1993 API Chapter
21.1) and with ISO 9951-1993(E). The FloBoss 504 performs 1992 AGA8 compressibility calculations
in accordance with AGA Report No. 8 1992 (API Chapter 14.2); for ISO calculations, the FloBoss 504
performs ISO 12213-2 compressibility. The flow calculation may be configured to use either Metric or
US units. Pulse fidelity/integrity checking at Level A through Level E is also performed according to
AGA/API 5-5 and ISO 6551-1982(E). These integrity levels are summarized as follows:
♦ Level A – This is the highest level of integrity; it provides continuous protection against errors.
Both verification and correction are performed by comparing two pulse streams from the
turbine. The two pulse streams are checked against each other to produce a corrected pulse
stream, which is then used in the flow calculation. Errors are indicated even when corrected.
For Level A, the FloBoss 504 employs a patent-pending algorithm and requires a high-
precision turbine with no more than 1% phase error between blades.
♦ Level B – This level provides continuous warning of errors by comparing two pulse streams
from the turbine against each other. For Level B, the FloBoss 504 employs a patent-pending
algorithm.
♦ Level C – This level provides automatic warning of errors at specified intervals by comparing
two pulse streams from the turbine against each other and requires a turbine with no more than
15% phase error between blades.
♦ Level D – This level provides manual warning of errors at specified intervals by comparing
the results of one pulse stream from the turbine visually against another means of
measurement, such as a mechanical meter.
♦ Level E – This is the lowest level of integrity; it provides no detection of errors by comparison
of the one pulse stream from the turbine to any other results, but instead depends entirely on
the quality of the installed equipment.
After power-up, the Master Controller Unit (MCU) enters the normal operation mode. The Sensor
Module (SM) then counts the pulses as they occur. Once every 992 ms, the SM reports to the MCU
the number of pulses received by its pulse inputs, as well as the static and auxiliary pressures. The
values are stored in temporary memory.
Once every Scan Period, the MCU processes the pulse counts, determines the number of pulse counts
since the last reading, and calculates a rate. Next, the static pressure and auxiliary pressure values are
read. Then the temperature is read and linearizing compensation is applied to the pressure readings if
necessary. The RTD is internally re-calibrated for every 5°C (9°F) change as sensed by the enclosure
temperature diagnostic input.
All resultant values are stored in the current value database. The values are taken from the current
value database and used to calculate the Minute, Hour, and Daily historical values.
Finally, the MCU enters a low-power mode and waits for the beginning of the next cycle.
Once a minute and once an hour, the values are logged along with other configured values to the
Historical Database. At the configured Contract Hour, the values are stored to the Daily Historical
Log and zeroed for the start of a new day.