body {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
line-height: 1.6;
color: #333;
max-width: 800px;
margin: 0 auto;
padding: 20px;
}
.calculator-container {
background-color: #f8f9fa;
border: 1px solid #e9ecef;
border-radius: 8px;
padding: 25px;
margin-bottom: 30px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.calc-header {
text-align: center;
margin-bottom: 25px;
color: #2c3e50;
}
.form-group {
margin-bottom: 20px;
}
label {
display: block;
margin-bottom: 8px;
font-weight: 600;
color: #495057;
}
input[type="number"] {
width: 100%;
padding: 10px;
border: 1px solid #ced4da;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.input-hint {
font-size: 0.85em;
color: #6c757d;
margin-top: 4px;
}
button.calc-btn {
width: 100%;
background-color: #007bff;
color: white;
border: none;
padding: 12px;
font-size: 16px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
transition: background-color 0.2s;
}
button.calc-btn:hover {
background-color: #0056b3;
}
#results-area {
margin-top: 25px;
background-color: #fff;
border: 1px solid #dee2e6;
border-radius: 4px;
padding: 20px;
display: none;
}
.result-row {
display: flex;
justify-content: space-between;
align-items: center;
padding: 10px 0;
border-bottom: 1px solid #eee;
}
.result-row:last-child {
border-bottom: none;
}
.result-label {
font-weight: 600;
color: #555;
}
.result-value {
font-size: 1.2em;
font-weight: bold;
color: #28a745;
}
.article-content {
margin-top: 40px;
}
h2 {
color: #2c3e50;
border-bottom: 2px solid #eee;
padding-bottom: 10px;
margin-top: 30px;
}
h3 {
color: #495057;
margin-top: 20px;
}
p {
margin-bottom: 15px;
}
ul {
margin-bottom: 15px;
}
.formula-box {
background-color: #e8f4fd;
padding: 15px;
border-left: 4px solid #007bff;
font-family: monospace;
margin: 15px 0;
}
function calculateDosing() {
// Get inputs
var flowRate = parseFloat(document.getElementById('flowRate').value);
var targetPPM = parseFloat(document.getElementById('targetPPM').value);
var activeStrength = parseFloat(document.getElementById('activeStrength').value);
var specificGravity = parseFloat(document.getElementById('specificGravity').value);
// Validation
if (isNaN(flowRate) || isNaN(targetPPM) || isNaN(activeStrength) || isNaN(specificGravity)) {
alert("Please fill in all fields with valid numbers.");
return;
}
if (activeStrength <= 0 || specificGravity <= 0) {
alert("Active Strength and Specific Gravity must be greater than 0.");
return;
}
// Calculation Logic
// Formula: Rate (L/hr) = (Flow (m3/hr) * PPM) / (Specific Gravity * Active Strength % * 10)
// Explanation of the factor 10:
// 1. PPM is mg/L or g/m3.
// 2. Active Strength is %. 1% = 10,000 ppm.
// 3. To convert appropriately with SG, we use the standard water treatment formula.
// Step 1: Calculate grams of active chemical required per hour
// Flow (m3/hr) * Target (g/m3) = grams/hr
var gramsActivePerHour = flowRate * targetPPM;
// Step 2: Calculate grams of solution required per hour
// gramsActive / (Strength / 100)
var gramsSolutionPerHour = gramsActivePerHour / (activeStrength / 100);
// Step 3: Convert grams of solution to Liters of solution
// Volume = Mass / Density
// Density in g/L = Specific Gravity * 1000
var densityGramsPerLiter = specificGravity * 1000;
var litersPerHour = gramsSolutionPerHour / densityGramsPerLiter;
// Alternate standard calculation for verification: (Q * PPM) / (10 * % * SG)
// litersPerHour = (flowRate * targetPPM) / (10 * activeStrength * specificGravity);
// Calculate other metrics
var mlPerMin = (litersPerHour * 1000) / 60;
var litersPerDay = litersPerHour * 24;
// Display Results
document.getElementById('resLitersPerHour').innerText = litersPerHour.toFixed(2) + " L/hr";
document.getElementById('resMlPerMin').innerText = mlPerMin.toFixed(2) + " mL/min";
document.getElementById('resDaily').innerText = litersPerDay.toFixed(1) + " L/day";
// Show result container
document.getElementById('results-area').style.display = 'block';
}
Understanding Chemical Dosing Calculations
Precise chemical dosing is fundamental to effective water treatment, industrial processing, and agriculture. Whether you are chlorinating drinking water, adjusting pH levels in wastewater, or adding nutrients to an irrigation system, calculating the correct dosing rate ensures process efficiency and safety.
This calculator determines the volumetric flow rate required for your dosing pump based on the process water flow, the desired chemical concentration, and the properties of the chemical being dosed.
The Dosing Formula
To calculate the required chemical feed rate in Liters per hour (L/hr), the standard formula used in the water treatment industry is:
Rate (L/hr) = (Q × D) / (10 × % × SG)
Where:
- Q: Water Flow Rate in cubic meters per hour (m³/hr).
- D: Dosage or Target Concentration in parts per million (PPM) or mg/L.
- %: The Active Strength of the chemical solution (e.g., 12.5 for 12.5%).
- SG: Specific Gravity of the chemical (Density in kg/L).
- 10: A constant conversion factor to align units.
Key Input Variables Explained
Water Flow Rate (m³/hr)
This is the volume of water passing through the injection point every hour. If your flow meter reads in Liters per minute (L/min), you must convert it to m³/hr by multiplying by 0.06.
Target Concentration (PPM)
The "Part Per Million" represents the desired residual or dosage. For example, in drinking water chlorination, you might aim for a dosage of 2.0 PPM to maintain a residual of 0.5 PPM after demand.
Active Strength (%)
Chemicals are rarely 100% pure. For example, commercial Sodium Hypochlorite is often sold at 10% to 15% strength. If you input 100% here, the calculator assumes you are dosing a pure liquid, which creates a much lower volume requirement.
Specific Gravity (SG)
The specific gravity represents the density of the chemical compared to water. Water has an SG of 1.0. Heavy chemicals like Sulphuric Acid (98%) have an SG around 1.84, while Sodium Hypochlorite (12.5%) usually has an SG around 1.15 to 1.20. Accounting for density is crucial because dosing pumps move volume, but chemical reactions depend on mass.
Why Calculation Accuracy Matters
Under-dosing can lead to unsafe water conditions, bacterial growth, or failure to meet environmental discharge regulations. Over-dosing wastes expensive chemicals, can damage equipment through corrosion, and may create toxic byproducts. Using an accurate calculation tool helps calibrate metering pumps correctly for optimal system performance.
Common Chemical Properties
- Sodium Hypochlorite (12.5%): SG ≈ 1.20
- Sulphuric Acid (98%): SG ≈ 1.84
- Caustic Soda (50%): SG ≈ 1.52
- PAC (Poly Aluminium Chloride): SG ≈ 1.20