Appendix a: derived functions – GF Signet 8900 Multi-Parameter Controller User Manual
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Signet 8900 Multi-Parameter
•
% Recovery is a derived measurement based on fl ow rate
only. In a reverse osmosis system, % Recovery is fl ow rate
in the permeate (product) compared to the fl ow rate of the
incoming feed water.
•
To measure % Recovery, the 8900 must have two fl ow
sensors connected. They may be located in the Feed line,
the Concentrate line or the Permeate line.
•
The 8900 provides 3 different methods for calculating
Recovery to accomodate any confi guration.
• Both
fl ow sensors must use the same timebase and units of
measure.
Appendix A: Derived Functions
When two or more measurements of the same type are present, the 8900 can calculate several derived functions from like pairs.
Up to three derived Functions can be defi ned and used as the source for display and output functions.
•
Flow, Temperature, Pressure, and Level channels must have matching units. (fl ow channels must also have same timebase)
•
Conductivity channels will automatically scale to μS/cm before the function calculation is made.
•
Three derived measurements can be applied to any set of sensors, regardless of type.
• Ratio:
Measurement 1 ÷ Measurement 2
• Difference:
Measurement 1 - Measurement 2
• Sum:
Measurement 1 + Measurement 2
•
% Passage and % Reject are derived from conductivity
measurements only, specifi cally for use in reverse osmosis
systems.
•
% Passage is the amount of contaminates remaining in the
product water compared to the level of contaminates in the
feed water. For example, if the feed water measures 100 μS
and the product water measures 5 μS, the % Passage is
(5 ÷ 100) x 100, or 5%.
•
% Reject is the amount of contaminates rejected to the
concentrate water compared to the amount of contaminates
in the feed water. For example, if the % Passage is 5%, the
% Reject is 95%.
•
Decreasing Reject values and increasing Passage values
usually indicate a problem with the RO membrane.
% Recovery
% Passage and % Reject
% Passage:
(Permeate ÷ Feed) x 100
% Reject:
[1 - (Permeate ÷ Feed)] x 100
RO Membrane
RO Membrane
RO Membrane
Feed
Concentrate
Permeate
RO Membrane
RO Membrane
RO Membrane
Feed
Concentrate
Permeate
% Recovery A: (Permeate ÷ Feed) x 100
In the Setup menu, select the option that represents
Feed
Permeate
% Recovery B: Permeate ÷ (Permeate + Concentrate) x 100
In the Setup menu, select the option that represents
Concentrate
Permeate
% Recovery C: [(Feed - Concentrate) ÷ Feed] x 100
In the Setup menu, select the option that represents
Concentrate
Feed
RO Membrane
RO Membrane
RO Membrane
Feed
Concentrate
Permeate
Feed
Concentrate
RO Membrane
RO Membrane
RO Membrane
Permeate