Choosing the correct pipe size can be confusing
Help Article ID | 36A |
At Just Spa Parts we realise that when it comes to choosing the correct pipe or fittings needed for your requirements, it can sometimes become a little confusing, especially when it comes to selecting the correct plumbing size. This Help Article is here to help you avoid the common mistakes made by so many when selecting the pipe & fitting size they need.
![Hot Tub Plumbing Pipe Sizes Explained Hot Tub Plumbing Pipe Sizes Explained](/c/images/2/1da25476how-to-measure-a-pipe-od-vernier-png.jpg)
Step 1
The first step is to measure your actual pipe's OD (Outside diameter) in mm. Using a set of Vernier’s is normally the quickest and most accurate way.
Helpful Tip
If you do not have access to a set of Verniers take a sheet of paper and wrap it around the pipe, mark where the paper overlaps. Straighten out and measure the distance in mm, this will now give you the pipe's circumference. Divide this by 3.14 which will provide you the pipe's diameter.
![Correct way to measure pipe](/c/images/2/ff66d2measure-pipe-not-fitting-png.jpg)
![dont mistake the fitting for pipe OD](/c/images/2/58349do-not-measure-a-fitting-png.jpg)
Step 2
Now you know your actual pipe OD (outside Diameter) you can select the correct pipe size. Use the charts bellow work out the size needed based off your actual pipes OD (outside diameter) in mm. Match your measurement with one of the figures in the outer column (Actual Outside Dia. mm)
METRIC PLUMBING
Note - Metric plumbing is not that common in domestic hot tubs and is more often used in Pools and commercial spas.
REF | TYPE | ACTUAL |
20mm | METRIC | 20mm |
32mm | METRIC | 32mm |
40mm | MERTIC | 40mm |
50mm | METRIC | 50mm |
63mm | MERTIC | 63mm |
75mm | METRIC | 75mm |
IMPERIAL PLUMBING
REF | TYPE | ACTUAL |
3/8 Inch | IMPERIAL | 14mm |
1/2 Inch | IMPERIAL | 21.5mm |
3/4 Inch | IMPERIAL | 28mm |
1 Inch | IMPERIAL | 33.4mm |
1-1/4 Inch | IMPERIAL | 42.16mm |
1-1/2 Inch | IMPERIAL | 48.26mm |
2 Inch | IMPERIAL | 60.33mm |
2-1/2 Inch | IMPERIAL | 73mm |
3 Inch | IMPERIAL | 88.9mm |