AS NZS 1301.441:2018 pdf free
AS NZS 1301.441:2018 pdf free.Methods of test for pulp and paper
Variable-area flow-measuring device, consisting of three variable-area flowmeters, each having a tapered glass column containing a metering float suspended by the air flow in the column (see Reference [7]). The three columns shall be chosen such that they enable measurement to be made on a continuous scale of flow rate from 10 ml/min to 3 000 ml/min, with some overlap of scales between columns. Each column shall be provided with a means of adjusting the flow rate (float-position knob) and a means of span calibration (calibrating knob). This type of instrument shall operate at a supply pressure of 10,3 kPa.
At air flow rates greater than 1 200 ml/min, the pressure drop in the Sheffield system is substantial and,to ensure the reproducibility of results, it is necessary that the tubing used to connect the flowmeter to the measuring head be carefully controlled with a length of 1,50 m±0,01 m and an internal diameter of 6,25 mm±0,25 mm. For the same reason, openings in valves and other fittings on the instrument shall not be changed from those provided by the instrument manufacturer.
The measuring head shall be connected to the air supply with an airtight seal and the air shall be fed into the gap between the two measuring lands through a narrow hole bored through the material of the measuring head. This can act as impedance in the measurement air line (see Figure 1, Key 4). The central space inside the inner land shall be vented to the atmosphere.
The test assembly shall have a suitable coupling through which the chosen flowmeter is connected to the tube leading to the measuring head. The tube, connecting the measuring head to the instrument,and the tube connectors have internal diameters that provide resistance to the air flow. Alteration of these components from those provided by the manufacturer may change the calibration and operation of the instrument.AS NZS 1301.441 pdf free download.
