Siemens SITRANS P Operating Instructions Manual page 270

Sealing plug / thread adapter
D.4 Dimensional drawings for accessory part
Thread adapter Ex d, M25 x 1.5 on M20 x 1.5 and
M25 x 1.5 on ½-14 NPT, dimensions in mm
Sealing plug Ex d ½ -14 NPT
270
①
Sealing ring: Use for dust protection "Ex t" type
of protection.
SITRANS P320/P420 with 4 to 20 mA/HART
Operating Instructions, 11/2019, A5E44852162-AC