Installation | 8631 Venturi
INSTALLATION
Piping Considerations:
A certain length of straight upstream and downstream piping is necessary to optimize the accuracy of any differential pressure device.
Upstream: The following tabulation provides the minimum straight upstream lengths (expressed as multiples of pipe ID) required for 0.0% and 0.5% additional potential affect in base flow accuracy.
Expander 0.75D to D w/length of D
Reduer 1.33D to D w/length of 2.3D
Expander 0.67D to D w/length of 2.5D
Reducer 3D to D w/length of 3.5D
Two 90° bends within 15D
Full bore ball or gate valve fully open
Single 90°bend
Upstream feature
Additonal Uncertainty Length
0.00% 0.50% 0.00% 0.50% 0.00% 0.50% 0.00% 0.50% 0.00% 0.50% 0.00% 0.50% 0.00% 0.50% 14D 3D 18D 3D 4D ------- 7D 5D 10.5D 2.5D 5.5D 3.5D 5.5D 3.5D
Downstream: For zero additional uncertainty due to downstream piping, ensure that there are no fittings for 1.5D downstream of the Venturi.
Lifting Instructions All Venturis may be lifted using a pair of lift points in the same plane. A four-point lift is preferable as it will reduce the stress on the Venturi. Rain Cap and Bird Screen Lift points The horizontal rain cap-bird screen lift point is solely for the lifting of the rain cap-bird screen alone. It must not be used for lifting the overall assembled Venturi with rain cap-bird screen.
The vertical rain cap-bird screen lift point may be used to lift the entire assembled venturi with rain cap-bird screen.
Flow Transmitter After installing the Venturi, the flow transmitter must be zero trimmed during comissioning before being placed into service.
Bulletin 8631 page 8
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