.flow-calc-container {
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
max-width: 800px;
margin: 20px auto;
padding: 25px;
border: 1px solid #e0e0e0;
border-radius: 12px;
background-color: #ffffff;
box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}
.flow-calc-header {
text-align: center;
margin-bottom: 25px;
}
.flow-calc-grid {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 20px;
margin-bottom: 20px;
}
.flow-calc-group {
display: flex;
flex-direction: column;
}
.flow-calc-label {
font-weight: 600;
margin-bottom: 8px;
color: #333;
}
.flow-calc-input, .flow-calc-select {
padding: 12px;
border: 1px solid #ccc;
border-radius: 6px;
font-size: 16px;
}
.flow-calc-btn {
background-color: #0073aa;
color: white;
padding: 15px;
border: none;
border-radius: 6px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
width: 100%;
transition: background-color 0.2s;
}
.flow-calc-btn:hover {
background-color: #005177;
}
.flow-calc-result {
margin-top: 25px;
padding: 20px;
background-color: #f9f9f9;
border-radius: 8px;
display: none;
}
.result-item {
display: flex;
justify-content: space-between;
padding: 8px 0;
border-bottom: 1px solid #eee;
}
.result-value {
font-weight: bold;
color: #0073aa;
}
.flow-article {
margin-top: 40px;
line-height: 1.6;
color: #444;
}
.flow-article h2 {
color: #222;
border-bottom: 2px solid #0073aa;
padding-bottom: 8px;
}
@media (max-width: 600px) {
.flow-calc-grid {
grid-template-columns: 1fr;
}
}
Inner Pipe Diameter
Diameter Unit
Millimeters (mm)
Centimeters (cm)
Meters (m)
Inches (in)
Flow Velocity
Velocity Unit
Meters/second (m/s)
Feet/second (ft/s)
Calculate Flow Rate
Results:
Cubic Meters per Hour (m³/h):
0
Liters per Minute (L/min):
0
US Gallons per Minute (GPM):
0
Cubic Feet per Second (ft³/s):
0
How to Calculate Volumetric Flow Rate in a Pipe
Understanding the volumetric flow rate is essential for hydraulic engineering, plumbing, and industrial process design. It represents the volume of fluid that passes through a given cross-sectional area per unit of time.
The Fundamental Formula
The calculation of volumetric flow rate ($Q$) in a pipe relies on the relationship between the cross-sectional area of the pipe and the average velocity of the fluid:
Q = A × v
Where:
Q is the volumetric flow rate.A is the cross-sectional area of the pipe ($\pi \times r^2$).v is the flow velocity.
Step-by-Step Calculation Guide
Determine the Inner Diameter: Measure the inside diameter (D) of the pipe. Ensure you use the internal dimension, as pipe wall thickness can vary.Calculate Cross-Sectional Area (A): Use the formula $A = \pi \times (D / 2)^2$. Convert units to meters if you want the result in standard metric units.Measure Fluid Velocity (v): This is the speed at which the fluid moves through the pipe (e.g., meters per second).Multiply Area by Velocity: The resulting figure is your flow rate.
Practical Example
Suppose you have a pipe with an inner diameter of 100 mm and the water is traveling at a velocity of 1.5 m/s .
Convert diameter to meters: 100 mm = 0.1 m.
Radius (r) = 0.1 / 2 = 0.05 m.
Area (A) = $\pi \times (0.05)^2 \approx 0.007854$ m².
Flow Rate (Q) = $0.007854 \times 1.5 = 0.011781$ m³/s.
To get m³/h: $0.011781 \times 3600 \approx 42.41$ m³/h.
Common Flow Velocity Guidelines
In most commercial plumbing and industrial applications, designers aim for specific velocity ranges to prevent erosion or sediment buildup:
Water Supply Lines: 1.5 to 2.5 m/s (5 to 8 ft/s).Suction Lines: 0.5 to 1.5 m/s (1.5 to 5 ft/s).Gravity Drains: 0.6 to 1.2 m/s (2 to 4 ft/s).
function calculateFlowRate() {
var diameter = parseFloat(document.getElementById('pipeDiameter').value);
var diameterUnit = document.getElementById('diameterUnit').value;
var velocity = parseFloat(document.getElementById('flowVelocity').value);
var velocityUnit = document.getElementById('velocityUnit').value;
if (isNaN(diameter) || isNaN(velocity) || diameter <= 0 || velocity < 0) {
alert("Please enter valid positive numbers for diameter and velocity.");
return;
}
// Convert Diameter to Meters
var diameterMeters;
if (diameterUnit === "mm") {
diameterMeters = diameter / 1000;
} else if (diameterUnit === "cm") {
diameterMeters = diameter / 100;
} else if (diameterUnit === "in") {
diameterMeters = diameter * 0.0254;
} else {
diameterMeters = diameter;
}
// Convert Velocity to Meters/Second
var velocityMS;
if (velocityUnit === "ft/s") {
velocityMS = velocity * 0.3048;
} else {
velocityMS = velocity;
}
// Calculate Area (A = pi * r^2)
var radius = diameterMeters / 2;
var area = Math.PI * Math.pow(radius, 2);
// Calculate Q (m3/s)
var flowM3s = area * velocityMS;
// Conversions
var m3h = flowM3s * 3600;
var lmin = flowM3s * 60000;
var gpm = flowM3s * 15850.3231;
var cfs = flowM3s * 35.3147;
// Display Results
document.getElementById('resM3h').innerText = m3h.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 4});
document.getElementById('resLmin').innerText = lmin.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resGPM').innerText = gpm.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2});
document.getElementById('resCFS').innerText = cfs.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 4});
document.getElementById('flowResult').style.display = 'block';
}