Obstruction Right Angle Bend Radius Angle Bend r=1D or less Opposed Blade Damper 30° Bend Tapered Contraction Sudden Contraction
±10% 10.0D 10.0D
±15% 3.5D 3.5D
10.0D 3.5D 3.5D 3.5D
3.5D 2.0D 2.0D 2.0D
Table 10: Uncertainty and Repeatability of Measurement Expected uncertainty of measurement with typical system obstruc- tions:
Straight Upstream Length
Required to Maintain
Note: For rectangular ducts D= Width + Height of Duct/2
On any particular installation repeatability of signal output is likely to be better than ±5%.
When calibrated on site (See Previous Page) uncertainty of mea- surement is likely to be better than ±5%.
MAINTENANCE No maintenance is normally required except where a high dust burden is likely to be encountered in the air stream. Deposits in the pressure holes will affect calibration and it is advisable to provide some means of access for cleaning when installing the AFG Flow Grid. The Series AFG Flow Grid is not field serviceable and should be returned if repair is needed (field repair should not be attempt- ed and may void warranty). Be sure to include a brief description of the problem plus any relevant application notes. Contact cus- tomer service to receive a return goods authorization number before shipping.
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Printed in U.S.A. 12/05
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