H2flow Controls
FlowVis®
14
Installation
8.3 Pipe Configurations other than those used by NSF for Testing
Piping configurations that are more demanding than those used by NSF for
testing FlowVis, e.g., installing an FV-3 right next to another fitting such as an
elbow, will result in a lower accuracy level than stated above. It is impossible to
determine the exact impact that each scenario will have, but like all flow meters
installed in larger pipe sizes, turbulence becomes an issue. The longer the run of
straight pipe before FlowVis, the better.
8.4 NSF 50 Accuracy Levels
The NSF 50 Standard for flow meters has five levels of accuracy (L1 - L5) that
are expressed as follows:
Level 1 (L1)
- Average of absolute values of all single point deviations must be
≤
2%. Single point deviations shall not exceed
±
4%.
Level 2 (L2)
- Average of absolute values of all single point deviations must be
≤
5%. Single point deviations shall not exceed
±
7.5%.
Level 3 (L3)
- Average of absolute values of all single point deviations must be
≤
10%. Single point deviations shall not exceed
±
12.5%.
Level 4 (L4)
- Average of absolute values of all single point deviations must be
≤
12.5%. Single point deviations shall not exceed
±
15%.
Level 5 (L5)
- Average of absolute values of all single point deviations must be
≤
15%. Single point deviations shall not exceed
±
20%.
