This calculator helps you estimate the water pressure at a given point in a plumbing system based on the flow rate and pipe characteristics. Understanding water pressure is crucial for designing efficient and effective plumbing systems, ensuring adequate water supply for various applications, and preventing issues like water hammer.
function calculateWaterPressure() {
var flowRateLPM = parseFloat(document.getElementById("flowRate").value);
var pipeDiameterMM = parseFloat(document.getElementById("pipeDiameter").value);
var pipeLengthM = parseFloat(document.getElementById("pipeLength").value);
var pipeRoughnessMM = parseFloat(document.getElementById("pipeRoughness").value);
var fluidViscosity = parseFloat(document.getElementById("fluidViscosity").value);
var fluidDensity = parseFloat(document.getElementById("fluidDensity").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous results
// Input validation
if (isNaN(flowRateLPM) || isNaN(pipeDiameterMM) || isNaN(pipeLengthM) || isNaN(pipeRoughnessMM) || isNaN(fluidViscosity) || isNaN(fluidDensity) ||
flowRateLPM <= 0 || pipeDiameterMM <= 0 || pipeLengthM <= 0 || pipeRoughnessMM <= 0 || fluidViscosity <= 0 || fluidDensity 4000), we'll use an approximation. For laminar flow, friction factor is 64/Re.
if (reynoldsNumber < 2100) { // Laminar flow
frictionFactor = 64 / reynoldsNumber;
} else { // Turbulent flow
// Explicit approximation of Colebrook equation (e.g., Haaland equation)
var term1 = Math.pow(reynoldsNumber, -0.5);
var term2 = -1.8 * Math.log10((pipeRoughnessM / pipeDiameterM) / 3.7 + Math.pow(6.9 / reynoldsNumber, 1.1));
frictionFactor = Math.pow(term1 + term2, -2);
// A simpler approximation for turbulent flow:
// frictionFactor = Math.pow(-2 * Math.log10((pipeRoughnessM / pipeDiameterM) / 3.7 + 1.765 / Math.pow(reynoldsNumber, 0.9))), -2);
}
// Calculate head loss due to friction using Darcy-Weisbach equation
// h_f = f * (L/D) * (v²/2g)
var gravity = 9.81; // m/s²
var headLossMeters = frictionFactor * (pipeLengthM / pipeDiameterM) * (Math.pow(fluidVelocity, 2) / (2 * gravity));
// Convert head loss from meters of fluid to pressure (Pascals)
// P = ρ * g * h
var pressureDropPa = fluidDensity * gravity * headLossMeters;
// Convert Pascals to a more common unit like Bar or PSI if desired.
// 1 Bar = 100,000 Pa
// 1 PSI ≈ 6894.76 Pa
var pressureDropBar = pressureDropPa / 100000;
var pressureDropPSI = pressureDropPa / 6894.76;
resultDiv.innerHTML = "