In Australia and New Zealand, for pool and spa applications, pressure PVC (PVC-U) pipe and fittings are used and these are manufactured to AS/NZS 1477.
AS/NZS 1477 pipe sizes refer to the "nominal diameter" (DN) and not the outer diameter. The outer diameter of "40mm pipe" is approximately 48mm and the outer diameter of "50mm pipe" is approximately 60mm. This is a very common cause of confusion to the typical pool owner.
PVC pipe can also have different thicknesses. PN9 is the most common, but sometimes PN12 pipe is used. PN12 is thicker, therefore the inner diameter is smaller. PVC fittings will fit any pipe thickness as the outer diameter does not change.
Most PVC fittings for pool applications are suitable for use with fittings and valves from the US market. However, European (metric) fittings are not compatiable.
Pipe and PVC Fittings for DWV and Ag pipe are also not usually not compatible.
| Size (DN) | Outer Diameter (mm) | PN9 ID (mm) | PN12 ID (mm) |
Compatibility with US NPS |
| 15mm | 21.20 - 21.50 | N/A | 18.30 | Interchangeable with ½" |
| 20mm | 26.60 - 26.90 | N/A | 23.65 | Interchangeablewith ¾" |
| 25mm | 33.40 - 33.70 | 30.45 | 29.75 | Interchangeablewith 1" |
| 32mm | 42.10 - 42.40 | 38.45 | 37.45 | Interchangeablewith 1¼" |
| 40mm | 48.10 - 48.40 | 44.05 | 42.75 | Interchangeablewith 1½" |
| 50mm | 60.20 - 60.50 | 55.15 | 53.65 | Interchangeablewith 2" |
| 65mm | 75.20 - 75.50 | 68.90 | 66.95 | Not compatible with 2½" |
| 80mm | 88.70 - 89.10 | 81.30 | 79.00 | Interchangeable with 3" |