Most of the sensor pipe threads are British Standard Pipe (BSP) threads. Between 1/16 up to 3/8, they differ by 1 additional thread over U.S. NPT. A NPT sender will screw into a metric hole for a few turns but will end up cross threading after 2 full turns. From the 1/2 NPT on up, they are the same threads per inch but the taper is different.

If a BSP to NPT (metric to U.S. NPT) adapter is not available, you can drill out the hole for the next size NPT and re-thread it then use a brass bushing if necessary.

NPT BSP
------- ----------
1/16-27 1/16-28
1/8-27 1/8-28
1/4-18 1/4-19
3/8-18 3/8-19
1/2-14 1/2-14
3/4-14 3/4-14
1-14 1-14

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