A wireless process communication adapter is provided. The adapter includes a housing having a plurality of openings. An end cap is coupled to a first opening of the plurality of openings. A field device coupling is disposed at the second of the plurality of openings. The housing, end cap and field device coupling define a chamber therein. At least one circuit board is disposed within the chamber, the circuit board has wireless communication circuitry disposed thereon and is coupleable to a field device through the field device coupling. In one aspect, substantially all remaining volume in the chamber is filled with a solid material. In another aspect, an explosion-proof barrier is provided in the field device coupling. Combinations of the aspects are also provided.