A ________ fitting is used when the pipe size is different than the pump suction size.

A ________ fitting is used when the pipe size is different than the pump suction size.

• A. Eccentric tapered reducer or increaser
• B. Concentric reducer
• C. Elbow
• D. Tee

Answer: (A)

When you’re tying into a pump, the fitting must both change the diameter and keep the flow path smooth and filled with liquid. An eccentric tapered reducer or increaser does exactly that: it provides a gradual bore change so the pipe size difference at the pump suction is accommodated, and the eccentric (offset) bore lets you position the larger end so the bottom of the line stays full. This prevents air pockets from forming at the suction and reduces turbulence, which is crucial for proper priming and steady pump operation. A concentric reducer changes diameter but centers the bore, which can still allow air space in horizontal runs and doesn’t control the bottom-fill as reliably. Elbows and tees alter direction or create branches and don’t address matching sizes, so they’re not used for adapting pipe size to a pump suction.

When you’re tying into a pump, the fitting must both change the diameter and keep the flow path smooth and filled with liquid. An eccentric tapered reducer or increaser does exactly that: it provides a gradual bore change so the pipe size difference at the pump suction is accommodated, and the eccentric (offset) bore lets you position the larger end so the bottom of the line stays full. This prevents air pockets from forming at the suction and reduces turbulence, which is crucial for proper priming and steady pump operation. A concentric reducer changes diameter but centers the bore, which can still allow air space in horizontal runs and doesn’t control the bottom-fill as reliably. Elbows and tees alter direction or create branches and don’t address matching sizes, so they’re not used for adapting pipe size to a pump suction.