Determining Water Equivalents: |
| One U.S. Gallon Water |
= |
3.785 Liters
3785 milliliters (mL)
8.34 pounds |
| One Cubic Foot Water |
= |
7.48 US Gallons |
| 2.3 ft. of water |
= |
1.0 PSI |
| 1 grain hardness |
= |
17.1 ppm |
|
 |
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|
Calculating Parts per Million to Grains per US Gallon: |
| A. To convert ppm of hardness to grains per US Gallon, divide by 17.1: |
| Calculation: |
|
ppm hardness
17.1 |
= |
grains/US Gallon |
|
| Example: |
|
250 ppm hardness
17.1 |
= |
14.61 grains per gallon |
|
|
|
|
| B. To convert grains per U.S. Gallon to parts per million of hardness, multiply by 17.1: |
| Calculation: |
|
| (Grains hardness) * (17.1) |
= |
ppm hardness |
|
| Example: |
|
| (14.61 grains) * (17.1) |
= |
249.83 ppm hardness |
|
|
|
|
| C. Softener Capacity: Estimate 25,000 grains removal capacity per cubic foot of resin: |
| Calculation: |
|
(Cubic feet of resin) (25,000)
(Feed hardness in grains) |
= |
Softener capacity in gallons |
|
| Example: |
|
(35 ft3) (25,000 grains/ft3)
(25 grains/gal) |
= |
35,000 gallons |
|
|
|
|
Calculating Reverse Osmosis System Recovery: |
| Calculation: |
|
| (Permeate GPM/Feed GPM) (100) |
= |
% Recovery |
|
| Example: |
|
| (75 GPM/100 GPM) (100) |
= |
75% Recovery |
|
|
|
|
Calculating Reverse Osmosis Salt Rejection: |
| Calculation: |
|
| (1 - (permeate TDS/feed TDS)) x 100 |
= |
% rejection |
|
| Example: |
|
|
|
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Calculating the Concentration Factor: |
| A. Recovery Based Concentration Factor: |
| Calculation: |
|
| 1 / (1-recovery) |
= |
concentration factor |
|
| Example: |
|
|
|
| B. Conductivity Based Concentration Factor: |
| Calculation: |
|
(Concentrate Conductivity – Permeate Conductivity)
(Feed Conductivity – Permeate Conductivity) |
= |
concentration factor |
|
| Example: |
|
(4000 us – 3 uS)
(1000 us – 3 uS) |
= |
4 |
|
|
|
|
Converting Temperature |
| A. Degree Fahrenheit to Degree Celsius: |
| Calculation: |
|
|
| Example: |
|
| (77°F – 32) (.556) |
= |
25.02°C |
|
| B. Degree Celsius to Degree Fahrenheit: |
| Calculation: |
|
| °C / (0.556 + 32) * 100 |
= |
°F |
|
| Example: |
|
| 25°C / (.556 + 32) * 100 |
= |
76.8°F |
|
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|
Calculating Chemical Injection Rates in Milliliters per Minute: |
| Calculation: |
|
Feed GPM * Chem PPM * (8.34)
(chemical lb per gallon) * 1,000,000 |
= |
GPM/minute * 3785 = ml/mn |
|
| Example: |
|
Feed GPM = 200
Chemical dosage PPM = 2.0
Chemical # per gallon = 10.48 |
| |
|
(200 * 2 * (8.34) * 3785)
10.48 * 1,000,000 |
= |
1.20 milliliters per minute of neat chemical |
|
| |
|
1.20 milliliters per minute
Percent dilution |
= |
milliliters per minute of a diluted solution
|
|
| Note: |
|
Note: Express percentages as decimals. |
|
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|
Calculating Chemical Dilutions (applicable to very dilute solutions*): |
| Calculation: |
|
| 8.34 * Vd * Cd / 100 * Dn |
= |
Vn |
|
| Where: |
|
Vn = Volume of neat chemical required, gallons
Vd = Dilution volume, gallons
Cd = Percent dilution by weight
Dn = Neat solution density, lb/gallon |
| Example: |
|
Vd = 200 gallons
Cd = 5%
Dn = 10.48 lb/gallon |
| |
|
| 8.34 * 200 * 5 / 100 * 10.48 |
== |
7.96 gallons |
|
| Note: |
|
*To calculate more concentrated solutions, use Avista’s Chemdose program. |
