Calculations for Elution Study
CALCULATIONS FOR ELUTION STUDY
AREA OF VESSEL CROSS SECTION
A = π r²
Where:
A = area of the vessel in square feet
π = 3.1415
r = radius of vessel in feet
Example:
A = 3.1415 × 2² = 12.6 ft²
VOLUME OF RESIN
V = A × D
Where:
V = volume of resin in cubic feet
A = area of vessel in square feet
D = depth of resin bed in feet
Example:
V = 12.6 × 3 = 37.8 ft³
MAXIMUM FLOW RATE OF BACKWASH
Max BWflow = 6.0 × A
Where:
Max BWflow = max flow of backwash in GPM
A = area of vessel in square feet
Example:
Max BWflow = 6.0 × 12.6 = 75 GPM
TOTAL FLOW OF BRINE AND DILUTION WATER DURING BRINE DRAW
Total BDflow = 1.9 × Asoftener
Where:
Total BDflow = total flow of brine and dilution water in GPM
A = area of vessel in square feet
Example:
Total BDflow = 1.9 × 12.6 = 24 GPM
FLOW OF BRINE DURING BRINE DRAW
BDflow = 0.385 × Total BDflow
Where:
BDflow = flow of brine in GPM
Total BDflow = total flow of brine and dilution water in GPM
Note: The eductor drive water ideally dilutes the brine in a 1.6 to 1.0 ratio (1 / 2.6 = 0.385)
Example:
BDflow = 0.385 × 24.0 = 9.2 GPM
AMOUNT OF BRINE NEEDED
Brine = Total Salt / 2.6
Where:
Brine = amount of 100% saturated brine in gallons
Total Salt = total salt needed
2.6 = lbs of salt in one gallon of 100% saturated brine at 70°F
Note: Total salt is determined by dosage × volume of resin. Dosages range from 6 to 15 lbs per cubic foot of resin. For this example, use 10 lb dosage per cubic foot of resin.
Example:
Brine = (37.8 × 10) / 2.6 = 145.4 gallons
TIME FOR BRINING
Time = Brine / BDflow
Where:
Time = time for brining in minutes
Brine = amount of 100% saturated brine in gallons
BDflow = flow of brine in GPM
Example:
Time = 145.4 / 9.2 = 15.8 minutes