{"id":624,"date":"2026-08-06T16:19:05","date_gmt":"2026-08-06T20:19:05","guid":{"rendered":"https:\/\/flextech-ind.com\/news\/?p=624"},"modified":"2026-08-06T16:19:05","modified_gmt":"2026-08-06T20:19:05","slug":"pressure-drop-calculations-in-flexible-hose-systems","status":"publish","type":"post","link":"https:\/\/flextech-ind.com\/news\/pressure-drop-calculations-in-flexible-hose-systems\/","title":{"rendered":"Pressure Drop Calculations in Flexible Hose Systems"},"content":{"rendered":"

At Flextech Industries, we work with engineers and procurement teams across chemical processing, power generation, oil and gas, and HVAC who assume flexible hose behaves like rigid pipe when it comes to flow resistance. It\u00a0doesn’t, and\u00a0getting pressure drop calculations in\u00a0flexible hose systems<\/a>\u00a0wrong means undersized pumps, inadequate flow rates, and expensive system corrections after installation.<\/p>\n

Why Flexible Hoses\u00a0Have a\u00a0Higher Flow Resistance Than Rigid Pipes<\/h2>\n

Internal geometry is the issue. Corrugated and convoluted hose designs create recirculation zones that rigid smooth-bore pipe simply\u00a0doesn’t\u00a0produce. Every convolution interrupts laminar flow, increases turbulence, and raises the effective friction factor well above what a standard\u00a0Moody\u00a0diagram predicts for equivalent pipe.<\/p>\n

Smooth-bore PTFE-lined hoses reduce this effect significantly, but they\u00a0don’t\u00a0eliminate\u00a0it. The liner creates a smoother flow path, but transitions at fittings and the compliance of the hose wall still contribute losses that rigid pipe calculations\u00a0won’t\u00a0capture.<\/p>\n

The practical consequence: if your team is applying rigid pipe friction factors to a flexible hose run,\u00a0you’re\u00a0underestimating pressure drop. That error compounds across longer runs and higher flow velocities.<\/p>\n

Learn all about chemical compatibility considerations for flexible hose selection.<\/a><\/p>\n

The Calculation Framework: Modified Darcy-Weisbach<\/h2>\n

The Darcy-Weisbach equation is the correct starting point:<\/p>\n

\u0394P = f \u00d7 (L\/D) \u00d7 (\u03c1v\u00b2\/2)<\/p>\n

Where \u0394P is pressure drop, f is the friction factor, L is hose length, D is internal diameter, \u03c1 is fluid density, and v is\u00a0flow\u00a0velocity.<\/p>\n

The equation itself\u00a0isn’t\u00a0the problem. The friction factor is.<\/p>\n

Why Manufacturer Data Is Not Optional<\/h3>\n

For rigid pipe, you can derive friction factor from surface roughness using established correlations. For flexible hose, that approach fails. The friction factor varies with hose construction,\u00a0annular corrugated, helical corrugated, and smooth-bore lined designs each produce different results,\u00a0and no universal correlation covers them accurately.<\/p>\n

Manufacturer-supplied pressure\u00a0drop\u00a0curves, derived from actual flow testing, are the only reliable source for this value. Using a generic friction factor because\u00a0it’s\u00a0convenient will give you a number that looks credible and is wrong.<\/p>\n

Flow Velocity as a Design Variable<\/h3>\n

Flow\u00a0velocity directly affects pressure drop and hose longevity. Keeping velocity within the range your hose manufacturer recommends\u00a0isn’t\u00a0just a wear concern;\u00a0it’s\u00a0a pressure management decision. Higher velocities amplify the friction losses caused by internal hose geometry, meaning the relationship between velocity and pressure drop in flexible hose is less forgiving than it is in rigid pipe.<\/p>\n

Installation Factors That Change Your Final Numbers<\/h2>\n

Hose routing decisions are part of the pressure drop calculation, not an afterthought.<\/p>\n

Factors that add resistance:<\/p>\n