08.12.2005
The new geometrical primary standard on basis of the principle of flow comparator (which was developed in the PTB and is patented) was assembled for the flow rates between 0.02 and 4 m³/h and was prepared for the first function test. The principle has been tested very successfully in the last two years with a small prototype used for flow rates below 5 l/h. Based on the mechanical concept it will be possible to calibrate meters with non-aggressive gases up to an pressure of 10 bar with an uncertainty of about 0.05 % (k = 2).
The main advantages in comparison to conventional piston devices are:
- constant pressure and temperature before and during the calibration (initial run time of meter under test is unlimited)
- very low uncertainty of the geometrical reference volume due to the measurement of the outer diameter of the piston and the driving mechanics (spindle)
- verifiability of internal leakage during the calibration process
- ability to calibrate meters under test, which set the flow rate by themselves (sonic nozzles, mass flow regulators)
Main application field will be the calibration of flow measurement devices as orifice meters, laminar flow elements, thermal mass flow meters, mass flow regulators and sonic nozzles.
Figure 1: The new assembled flow rate comparator up to 4 m³/h, general view and view of the driving unit.
Contact person:
R. Kramer, FB 1.4, AG 1.42, E-mail: rainer.kramer@ptb.de