Faucet Aerator Threads vs. NPT Pipe Thread
Comparing 2 standards across 13 specifications. 13 key differences identified.
Faucet aerators utilize standardized ultra-fine metric and imperial screw threads to attach flow restrictors and stream straighteners to residential and commercial spouts. Common sizes include Standard M24×1.0 male, 55/64"-27 female, Junior M18.5×1.0, and Tom Thumb M16.5×1.0; bathroom lavatory faucets are commonly EPA WaterSense-certified for reduced flow, though the WaterSense program does not cover kitchen faucets.
NPT (National Pipe Taper) is the standard North American tapered pipe thread governed by ANSI/ASME B1.20.1. Featuring a 60° thread flank angle and a 1:16 taper rate (0.75 inches per foot), NPT achieves sealing through flank wedging and deformation, requiring PTFE tape or pipe sealant to prevent spiral leak paths.
Specification Comparison Table
13 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standard Governing Body
|
ASME A112.18.1 / CSA B125.1 / NSF 61 | ANSI / ASME B1.20.1 |
|
Standard / Regular Size (Metric)
|
M24 × 1.0 mm (Male) | M22 × 1.0 mm (Female) | — |
|
Standard / Regular Size (US Imperial)
|
15/16"-27 UNS (Male) | 55/64"-27 UNS (Female) | — |
|
Junior Size
|
M18.5 × 1.0 mm (Male) | 13/16"-27 UNS (Female) | — |
|
Tom Thumb / Tiny Junior
|
M16.5 × 1.0 mm (Male) | 5/8"-27 UNS (Female) | — |
|
Standard Flow Rate (Bathroom WaterSense / Kitchen Federal Max)
|
1.2–1.5 GPM bathroom lavatory, EPA WaterSense-certified | up to 2.2 GPM kitchen, per the federal EPAct maximum (EPA WaterSense has no kitchen faucet certification program) | — |
|
Sealing Method
|
EPDM rubber flat washer compressed against spout shoulder | — |
|
Thread Form & Flank Angle
|
— | 60° symmetric truncated V-thread |
|
Taper Ratio
|
— | 1:16 (0.75 in/ft or 1° 47' with centerline) |
|
Common Pitches (TPI)
|
— | 1/8": 27 TPI | 1/4"-3/8": 18 TPI | 1/2"-3/4": 14 TPI | 1"-2": 11.5 TPI |
|
Sealing Mechanism
|
— | Thread flank interference fit + PTFE tape / anaerobic sealant |
|
Max Working Pressure @ 23°C (73°F)
|
— | Up to 5,000–10,000 PSI (dependent on pipe schedule/fitting) |
|
Primary Geographical Region
|
— | United States, Canada, and Mexico |