Which modification most effectively minimizes pressure drop in a long compressed air piping system?

Which modification most effectively minimizes pressure drop in a long compressed air piping system?

• A. Larger pipe diameter
• B. Higher supply pressure
• C. Longer runs
• D. Narrower pipe diameter

Answer: (A)

The main factor here is friction losses along a long pipe. Pressure drop in a pipe comes from the resistance the air encounters as it flows, which grows with velocity and with the length of the pipe. If you increase the pipe’s diameter, the cross-sectional area goes up, so for the same flow rate the air moves more slowly. Since friction losses depend strongly on velocity (and on the length-to-diameter relationship in the flow equations), reducing velocity and the L/D effect dramatically lowers the pressure drop along the run. In other words, a larger diameter pipe carries the same air with less resistance, so the pressure at the end stays higher. Raising the supply pressure doesn’t reduce the friction loss along the length; it merely starts you at a higher pressure, so you can still lose a substantial amount across the same piping. A longer run increases the pressure drop, while a narrower diameter increases it, making those options worse for minimizing drop.

The main factor here is friction losses along a long pipe. Pressure drop in a pipe comes from the resistance the air encounters as it flows, which grows with velocity and with the length of the pipe. If you increase the pipe’s diameter, the cross-sectional area goes up, so for the same flow rate the air moves more slowly. Since friction losses depend strongly on velocity (and on the length-to-diameter relationship in the flow equations), reducing velocity and the L/D effect dramatically lowers the pressure drop along the run. In other words, a larger diameter pipe carries the same air with less resistance, so the pressure at the end stays higher.

Raising the supply pressure doesn’t reduce the friction loss along the length; it merely starts you at a higher pressure, so you can still lose a substantial amount across the same piping. A longer run increases the pressure drop, while a narrower diameter increases it, making those options worse for minimizing drop.