.flow-rate-calculator-container {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 0 auto;
color: #333;
line-height: 1.6;
}
.frc-calculator-card {
background: #ffffff;
border: 1px solid #e0e0e0;
border-radius: 8px;
padding: 30px;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
margin-bottom: 40px;
}
.frc-input-group {
margin-bottom: 20px;
}
.frc-label {
display: block;
font-weight: 600;
margin-bottom: 8px;
color: #2c3e50;
}
.frc-input-wrapper {
display: flex;
gap: 10px;
}
.frc-input {
flex: 2;
padding: 12px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
}
.frc-select {
flex: 1;
padding: 12px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
background-color: #f9f9f9;
}
.frc-btn {
background-color: #0073aa;
color: white;
border: none;
padding: 14px 24px;
font-size: 18px;
font-weight: bold;
border-radius: 4px;
cursor: pointer;
width: 100%;
transition: background-color 0.2s;
}
.frc-btn:hover {
background-color: #005177;
}
.frc-results {
background-color: #f0f7ff;
border-left: 5px solid #0073aa;
padding: 20px;
margin-top: 25px;
display: none;
}
.frc-result-item {
display: flex;
justify-content: space-between;
margin-bottom: 10px;
padding-bottom: 10px;
border-bottom: 1px solid #dcebf7;
}
.frc-result-item:last-child {
border-bottom: none;
margin-bottom: 0;
padding-bottom: 0;
}
.frc-result-label {
font-weight: 600;
}
.frc-result-value {
font-family: monospace;
font-size: 18px;
color: #0073aa;
font-weight: 700;
}
.frc-error {
color: #d63638;
margin-top: 10px;
display: none;
font-weight: bold;
}
h2, h3 {
color: #23282d;
margin-top: 30px;
}
p {
margin-bottom: 15px;
}
.frc-formula-box {
background: #f1f1f1;
padding: 15px;
border-radius: 4px;
font-family: monospace;
text-align: center;
font-size: 1.2em;
margin: 20px 0;
border: 1px solid #ddd;
}
function calculatePipeFlow() {
// Get Elements
var diameterInput = document.getElementById('frc_diameter');
var diameterUnit = document.getElementById('frc_diameter_unit').value;
var velocityInput = document.getElementById('frc_velocity');
var velocityUnit = document.getElementById('frc_velocity_unit').value;
var resultsArea = document.getElementById('frc_results_area');
var errorMsg = document.getElementById('frc_error_msg');
// Parse Values
var d_val = parseFloat(diameterInput.value);
var v_val = parseFloat(velocityInput.value);
// Validation
if (isNaN(d_val) || isNaN(v_val) || d_val <= 0 || v_val < 0) {
errorMsg.style.display = 'block';
resultsArea.style.display = 'none';
return;
} else {
errorMsg.style.display = 'none';
resultsArea.style.display = 'block';
}
// Normalize Diameter to Meters (m)
var d_meters = 0;
if (diameterUnit === 'mm') d_meters = d_val / 1000;
else if (diameterUnit === 'cm') d_meters = d_val / 100;
else if (diameterUnit === 'm') d_meters = d_val;
else if (diameterUnit === 'in') d_meters = d_val * 0.0254;
else if (diameterUnit === 'ft') d_meters = d_val * 0.3048;
// Normalize Velocity to Meters per Second (m/s)
var v_ms = 0;
if (velocityUnit === 'ms') v_ms = v_val;
else if (velocityUnit === 'fts') v_ms = v_val * 0.3048;
else if (velocityUnit === 'kmh') v_ms = v_val / 3.6;
else if (velocityUnit === 'mph') v_ms = v_val * 0.44704;
// Calculate Area (A = pi * r^2 = pi * (d/2)^2) in m²
var radius = d_meters / 2;
var area_m2 = Math.PI * Math.pow(radius, 2);
// Calculate Flow Rate (Q = A * v) in m³/s
var flow_m3s = area_m2 * v_ms;
// Convert Results
var res_m3h = flow_m3s * 3600; // m³/h
var res_ls = flow_m3s * 1000; // Liters/s
var res_gpm = flow_m3s * 15850.32; // US GPM
var res_cfm = flow_m3s * 2118.88; // CFM (ft³/min)
// Update DOM
document.getElementById('res_m3h').innerHTML = res_m3h.toFixed(2) + ' m³/h';
document.getElementById('res_ls').innerHTML = res_ls.toFixed(2) + ' L/s';
document.getElementById('res_gpm').innerHTML = res_gpm.toFixed(2) + ' GPM';
document.getElementById('res_cfm').innerHTML = res_cfm.toFixed(2) + ' CFM';
document.getElementById('res_area').innerHTML = area_m2.toFixed(4) + ' m²';
}
Understanding the Formula to Calculate Flow Rate in a Pipe
Calculating the volumetric flow rate of a liquid moving through a pipe is a fundamental task in fluid mechanics, plumbing, and civil engineering. Whether you are designing an irrigation system, sizing a pump for a swimming pool, or analyzing industrial piping, understanding the relationship between pipe size, velocity, and flow rate is essential.
The Flow Rate Equation
The most basic formula to calculate the flow rate ($Q$) assumes the pipe is full of liquid and the velocity is constant. The formula relies on the Continuity Equation:
Q = A × v
Where:
- Q = Volumetric Flow Rate (e.g., m³/s, GPM)
- A = Cross-Sectional Area of the pipe (e.g., m², ft²)
- v = Average Velocity of the fluid (e.g., m/s, ft/s)
Step 1: Calculate the Cross-Sectional Area
Before you can find the flow rate, you must determine the area of the pipe's cross-section. For a standard round pipe, the area is calculated using the internal diameter ($d$):
A = π × (d / 2)² or A = (π × d²) / 4
Note: It is critical that the units for diameter match the units used for velocity. For example, if velocity is in meters per second, the diameter should be converted to meters before calculating the area.
Step 2: Multiply Area by Velocity
Once you have the area ($A$) and the velocity ($v$), simply multiply them to get the flow rate ($Q$).
Example: If a pipe has an internal area of $0.05 \text{ m}^2$ and the water is flowing at a speed of $2 \text{ m/s}$, the flow rate is:
$Q = 0.05 \text{ m}^2 \times 2 \text{ m/s} = 0.1 \text{ m}^3/\text{s}$
Common Unit Conversions
In real-world scenarios, you will often encounter mixed units. Here are common conversion factors used in this calculator:
- 1 m³/s = 1,000 Liters per second (L/s)
- 1 m³/s = 3,600 Cubic meters per hour (m³/h)
- 1 m³/s ≈ 15,850 US Gallons per minute (GPM)
- 1 m³/s ≈ 2,118.9 Cubic feet per minute (CFM)
Factors Affecting Flow Rate
While the formula $Q = A \times v$ is geometrically correct, achieving a specific velocity depends on factors like:
- Pressure Differential: The force driving the fluid.
- Friction Loss: Resistance caused by the pipe material and internal roughness.
- Viscosity: The thickness of the fluid (e.g., oil vs. water).
- Fittings and Bends: Valves and elbows create turbulence that reduces velocity.
For complex systems requiring pressure drop calculations, engineers use the Darcy-Weisbach or Hazen-Williams equations, but for determining capacity based on known velocity, the Continuity Equation used above is the standard.