Air calibration facility - The Bulderbaan
The air flow test facility, also known as the Bulderbaan, conducts first time verification, control and recalibration of volume, mass, and dP meters, using atmospheric air in the flow range of 65-25000 m3/h, Ucmc 0,23%.
Air flow calibration facility - one of the largest in the world
With its 14 m in length and 1,8 m in height, the air flow calibration facility is one of the largest of its kind in the world, especially due to its flow range capacity from 65 (Q-min) to 25000 m3/h (Q-max).
The air facility consists of five parallel reference lines, and a measuring line in series with these, where the meter under test (MUT) is located.
The air flow facility operates according to the suction principle under atmospheric conditions, where two RPM controlled centrifugal blowers draw air from the calibration room, through the meter under test, and then through the reference strings containing the working standards further downstream.
- (BU201) Blower A: Supplies WS201, WS202, and WS203 with air flow
- (BU202) Blower B: Supplies WS204, and WS205 with air flow
Flow meter types:
The air calibration facility can handle all types of flow meters for measurement of air and other gasses, including USM, turbine meters, swirl meters, coriolis meters, flare gas meters, etc. up to 50” in diameter.
Take tour in the air flow calibration facility - the Bulderbaan
How does the Bulderbaan conduct air flow calibration?
The butterfly valves POV201-205 are regulators, used to control the flow going through each corresponding working standard (WS). They also function as shut-offs to control the flow distribution, making sure that a single reference string can be used or multiple in parallel, if needed. Relevant reference strings are chosen based on flow rate requirement and meter size.
After each working standard and MUT, a thermistor is located, which measures the air temperature under calibration, so that the results can be corrected for temperature differences between the MUT and the Working standards.
Similarly, a differential pressure transmitter PDT201 measures the pressure differences between the working standards, MUT and ambient so that the results can be corrected for pressure differences.
The error is then determined by comparing the indicated output of the MUT to the actual real flow, which is determined by the working standards with the appropriate corrections in terms of temperature and pressure differences throughout the loop.
Before calibration can begin, the meter and the selected working standards are conditioned for at least 5-20 minutes. Additional conditioning is performed when changing flowrate and/or working standards, in order to stabilize the loop temperature and pressure.
The calibration is performed in descending order, with the highest specified flow rate first.
Additionally, an adjustment of the MUT can also be carried out after determination of the error reading at each flow point. The adjustment is meter specific (polynomial, linear or point to point) and can be carried out by the staff.
Does the Bulderbaan operate according to a BIPM approval?
In the begining of 2020, FORCE Technology will apply for the BIPM, expecting to get the BIPM approval by the end of 2020.
In 2020, FORCE Technology will work on reaching a lower Ucmc estimated at level 0,19%.
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