Napkin Diagrams

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Tag Archives: fluid flow

Pressure Drops In Pipes: Part 2, Series and Parallel

This is Part 2 in a series on pressure drops in pipes. Part 1 covered the basic concepts and equations (1-4b). It is recommended to read that before proceeding, or to have it open along side this article for reference.

Symmetrical Parallel Pipes

Figure 1. Liquid flow branching into two symmetrical pathways before rejoining.

A single pipe is not usually sufficient to solve a real—life problem. Instead, systems of pipes, often quite complex, are used to achieve all desired results. The math, as a result, becomes more difficult, but where would be the fun if it was easy?
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Pressure Drops In Pipes: Part 1, Basics

Stack of Pipes

A a fluid flows through a pipe, it will experience a natural pressure drop due to several factors. Friction is a major player, which itself involves flow velocity, pipe dimensions, and possibly internal pipe roughness. Height changes across the length of a pipe also contribute to pressure drops. Any and all fittings, coupling, et cetera will account for a part of any drops as well, although less so than the former two. Pressure drop can be related to head loss, a way of measuring the energy drop, with Equation 1, where ΔP is pressure drop, ρ is fluid density, g is gravity, and Δh is height difference.
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