14
SYSTEM PERFORMANCE
Rev C
HOW TO DETERMINE RATE OF FLOW FROM THE MERLIN SYSTEM - WORLD
Example
Inlet Water TDS (measured)
300 ppm
Inlet Water Temperature
10°C
Inlet Pressure
4.1 bar
3/8-inch Tubing
4.6 m long
Obstructions in Permeate Line
One 90° elbow
Elevation Difference Between Merlin and Faucet
1.8 m
Post Filter?
Yes
Faucet? Yes
Assigned Values
Pressure Drop per Obstruction
0.03 bar
Pressure Drop per Postfilter
0.21 bar
Pressure Drop in Elevation
0.095 bar per meter
(meters Faucet is above Merlin)
1.
Determine the Inlet TDS =
300 ppm
2.
Determine the Inlet Water Temperature =
10°C
3.
Determine the Net Driving Pressure of the Merlin system
Net Driving Pressure = Inlet Pressure - System Pressure Drop
3A.
Calculate the Flow Rate Adjustment Factor
This factor will be used with Table 1 to adjust the TDS of Inlet Water from 750 ppm to 300 ppm.
-0.0002 (300 ppm) + 0.15 =
0.34 Lpm
3B.
Calculate the Tubing Pressure Drop
Inlet Pressure
= 4.1 bar
Water
Temp
=
10°C
Use Table 1 to estimate flow rate, 750 ppm NaCl @ 10°C and 4.1 bar = 1.85
Lpm
Adjust Table data for actual TDS using the Flow Rate Adjustment Factor 0.34 Lpm
Tubing Flow Rate = 1.85 Lpm
+ 0.34 Lpm = 2.19 Lpm @ 300 ppm NaCl
Use Figure 4 to determine the pressure drop for .304 meter tubing = 0.0095 bar
Tubing Pressure Drop for 4.6 m = 4.6/0.304 x 0.0095 bar =
0.143 bar
3C.
Calculate the Obstruction Pressure Drop
1 obstruction (the elbow) X 0.03 bar =
0.03 bar
3D.
Calculate Elevation Pressure Drop
1.83 m elevation X 0.095 bar =
0.18 bar
3E.
Calculate Postfilter Pressure Drop
1 postfilter X 0.21 bar =
0.21 bar
3F.
Calculate Faucet Pressure Drop
4.1 bar - 0.14 bar - 0.03 bar - 0.18 bar - 0.21 bar = 3.54 bar
Use Table 1 to estimate flow rate, 750 ppm NaCl @ 10°C and 3.54 bar = 1.32 Lpm
Adjust Table Data for actual TDS using the Flow Rate Adjustment Factor 0.34 Lpm
1.32 Lpm + 0.34 Lpm
= 1.66 Lpm @ 300 ppm NaCl
Use Figure 8 and the Inlet Flow Rate of 1.66 Lpm to estimate the Faucet Pressure Drop =
0.31 bar
3G.
Calculate the System Pressure Drop
(System Pressure Drop = Tubing PD + Obstruction PD + Elevation PD + Postfilter PD + Faucet PD
0.14 bar + 0.03 bar + 0.18 bar + 0.21 bar + 0.31 bar =
0.87bar
3H.
Determine the Net Driving Pressure
(
Net Driving Pressure = Merlin Inlet Pressure - System Pressure Drop)
4.1 bar - 0.87 bar =
3.23 bar
4.
Determine the Merlin Flow Rate
Use Table 1 to estimate flow rate, 750 ppm NaCl @ 3.23 bar and 10°C = 1.44 Lpm
Adjust Table Data for actual TDS using the Flow Rate Adjustment Factor 0.34 Lpm
1.44 Lpm + 0.34 Lpm = 1.78 Lpm
TOTAL MERLIN FLOW RATE = 1.78 Lpm
Actual results may vary. Membrane performance may vary ± 15%.