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ISO 8791-2:2013 pdf free

ISO 8791-2:2013 pdf free.Paper and board一Determination of roughness/smoothness (air leak methods)
Flowmeter. The flow rate shall be measured by variable-area flowmeters which offer optional flow rate measurements in the ranges 5 ml/min to 150 ml/min, 50 ml/min to 500 ml/min and, on some instruments, 300 ml/min to 3 000 ml/min. These three variable-area flowmeters shall be capable of being read to within 2 ml/min, 5 ml/min and 20 ml/min respectively. The variable area flowmeter may be replaced by another kind of air flowmeter having a measuring range suitable for the material measured that allows the air flow to be determined with an error of less than±5 ml/min or±5 % whichever is greater.
One capillary tube shall be provided for verifying the calibration of each variable-area flowmeter. The capillary tubes shall be within the working range of the relevant flowmeter and shall themselves be accurately calibrated against a reliable standard (e.g. a soap-bubble meter) under the same pressure difference as that in the measuring head (Annex B gives details of the calibration of capillary tubes and variable-area flowmeters).
Place the instrument on a rigid level bench. Level the instrument, ensure that no vibration can cause erroneous readings, and turn on the air supply.
Decide which variable-area flowmeter will be used for the test, selecting, where possible, the variable-area flowmeter which will give a reading in the upper 80 % of the range with the 1,47 kPa manostat weight. Do not use air flows above 1 200 ml/ min because at high air flows the pressure drop between the flowmeter and the measuring head can be sufficient to render the calibration of the variable-area flowmeter invalid.
Set the valves at the bottom of the variable-area flowmeters so that air flows through the selected variable-area flowmeter. When the air flow has started, gently place the 1,47 kPa manostat weight on the shaft and start it spinning. It should continue to spin smoothly.ISO 8791-2 pdf download.

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