Pump Discharge Flow Rate Calculator
.pump-calculator-widget {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 20px auto;
padding: 25px;
background: #f9fbfd;
border: 1px solid #e1e4e8;
border-radius: 8px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.pump-calculator-widget h3 {
color: #2c3e50;
margin-top: 0;
border-bottom: 2px solid #3498db;
padding-bottom: 10px;
margin-bottom: 20px;
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.pump-input-group {
margin-bottom: 20px;
}
.pump-input-group label {
display: block;
font-weight: 600;
margin-bottom: 8px;
color: #34495e;
}
.pump-input-group input {
width: 100%;
padding: 12px;
border: 1px solid #cbd5e0;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
transition: border-color 0.3s;
}
.pump-input-group input:focus {
border-color: #3498db;
outline: none;
}
.pump-help-text {
font-size: 0.85em;
color: #7f8c8d;
margin-top: 5px;
}
.pump-btn {
background-color: #3498db;
color: white;
border: none;
padding: 14px 24px;
font-size: 16px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
width: 100%;
transition: background-color 0.3s;
}
.pump-btn:hover {
background-color: #2980b9;
}
.pump-results {
margin-top: 25px;
background: white;
padding: 20px;
border-radius: 4px;
border: 1px solid #eee;
display: none;
}
.pump-result-row {
display: flex;
justify-content: space-between;
align-items: center;
padding: 10px 0;
border-bottom: 1px solid #f1f1f1;
}
.pump-result-row:last-child {
border-bottom: none;
}
.pump-result-label {
color: #555;
font-weight: 500;
}
.pump-result-value {
font-weight: bold;
color: #2c3e50;
font-size: 1.1em;
}
.pump-error {
color: #e74c3c;
margin-top: 10px;
display: none;
font-weight: bold;
}
.article-content {
max-width: 800px;
margin: 40px auto;
line-height: 1.6;
color: #333;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}
.article-content h2 {
color: #2c3e50;
margin-top: 30px;
}
.article-content ul {
margin-bottom: 20px;
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.formula-box {
background: #f0f4f8;
padding: 15px;
border-left: 4px solid #3498db;
font-family: monospace;
margin: 20px 0;
}
function calculateFlowRate() {
var diameterInput = document.getElementById('pipeDiameter');
var velocityInput = document.getElementById('flowVelocity');
var errorDiv = document.getElementById('pumpError');
var resultDiv = document.getElementById('pumpResult');
var d_mm = parseFloat(diameterInput.value);
var v_ms = parseFloat(velocityInput.value);
// Reset display
errorDiv.style.display = 'none';
resultDiv.style.display = 'none';
// Validation
if (isNaN(d_mm) || isNaN(v_ms) || d_mm <= 0 || v_ms <= 0) {
errorDiv.style.display = 'block';
return;
}
// Calculation Logic
// 1. Convert Diameter from mm to meters
var d_m = d_mm / 1000;
// 2. Calculate Cross-Sectional Area (A = pi * r^2)
// radius = diameter / 2
var radius_m = d_m / 2;
var area_m2 = Math.PI * (radius_m * radius_m);
// 3. Calculate Flow Rate (Q = A * v) in m³/s
var q_m3s = area_m2 * v_ms;
// 4. Conversions
var q_m3h = q_m3s * 3600; // Cubic meters per hour
var q_lpm = q_m3s * 60000; // Liters per minute
var q_lps = q_m3s * 1000; // Liters per second
var q_gpm = q_lpm / 3.78541; // US Gallons per minute
// Display Results
document.getElementById('resM3h').innerText = q_m3h.toFixed(2) + " m³/h";
document.getElementById('resLpm').innerText = q_lpm.toFixed(2) + " L/min";
document.getElementById('resGpm').innerText = q_gpm.toFixed(2) + " GPM";
document.getElementById('resLps').innerText = q_lps.toFixed(2) + " L/s";
resultDiv.style.display = 'block';
}
Understanding Pump Discharge Flow Rate
Calculating the discharge flow rate of a pump is a fundamental task in fluid mechanics, civil engineering, and industrial process management. The flow rate determines how much volume of liquid is moved over a specific period, which is critical for sizing pipes, selecting pump motors, and ensuring system efficiency.
The Flow Rate Formula
The most common method to calculate flow rate inside a pipe—assuming the pipe is full of liquid—is based on the Continuity Equation. The formula relates the flow rate ($Q$) to the cross-sectional area of the pipe ($A$) and the average velocity of the fluid ($v$).
Q = A × v
Where:
- Q = Volumetric Flow Rate (e.g., m³/s)
- A = Cross-sectional Area of the pipe (m²)
- v = Average Fluid Velocity (m/s)
How to Calculate Area (A)
Since most pipes are cylindrical, the cross-sectional area is calculated using the internal diameter ($d$). If you are measuring the diameter in millimeters, you must first convert it to meters for standard SI calculations.
The formula for Area is: A = π × (d / 2)² or A = (π × d²) / 4.
Example Calculation
Let's say you have a discharge pipe with an internal diameter of 100 mm and the fluid is moving at a velocity of 2 m/s.
- Convert Diameter: 100 mm = 0.1 meters.
- Calculate Area: A = π × (0.1 / 2)² = 3.14159 × 0.0025 ≈ 0.00785 m².
- Calculate Flow ($Q$): Q = 0.00785 m² × 2 m/s = 0.0157 m³/s.
- Convert to m³/h: 0.0157 × 3600 ≈ 56.52 m³/h.
Factors Affecting Discharge Flow
While the calculator above provides a theoretical maximum based on velocity and area, real-world discharge rates are influenced by:
- Friction Loss: As fluid moves through pipes and fittings, friction reduces the pressure and potential flow rate.
- Head Pressure: The vertical distance the pump must lift the fluid (Static Head) significantly impacts the output.
- Fluid Viscosity: Thicker fluids (like oil) flow more slowly than water at the same pressure.
- Pump Efficiency: Mechanical wear and impeller design affect the actual output compared to the theoretical rating.
Common Units Used
Depending on your industry and location, flow rate is measured in various units. This calculator provides conversions for the most common ones:
- m³/h (Cubic Meters per Hour): Standard in industrial water treatment and chemical processing in Metric regions.
- L/min (Liters per Minute): Common for smaller hydraulic systems and consumer pumps.
- GPM (Gallons Per Minute): The standard unit in the United States for HVAC, fire protection, and plumbing.