[JimWoo50]

Anyone using a Positech 4211 oil cooler recall the size of the fittings to connect it to the oil hoses? I tried a AN-8 but the pipe thread side was too small. How does one measure the pipe thread size of these fittings? from the outside of the threads or the size of the opening?

 

[john.schwaner]

NPT OD to Pipe Size Chart

Male Tapered Pipe thread (NPT) is measured from the outside diameter (thread crest) and then referenced to the chart below:

Pipe Size Thread Outside Diameter, inch, approximate
1/16 : 0.310
1/8 : 0.405
1/4 : 0.540
3/8 : 0.675
1/2 : 0.840
3/4 : 1.050
1 : 1.315
1-1/4 : 1.660
1-1/2 : 1.900
2 : 2.375

Female or Boss NPT size is measured at the thread crest using the chart below:

Pipe Size Thread Outside Diameter, inch, approximate
1/16 | 0.258
1/8 : 0.340
1/4 : 0.442
3/8 : 0.557
1/2 : 0.715
3/4 : 0.925

To determine what the NPT size for an AN fitting requires looking at a chart.