Humidity sensor with improved contaminant sealing

An apparatus for measuring humidity of air flowing in a conduit, comprising:

• a probe comprising a probe arm configured to be inserted into the conduit;
• a humidity sensor element disposed at a distal end of the probe arm;
• and
• a filter connectable with the probe arm to enclose the humidity sensor element, the filter comprising a filter housing that defines an interior in which the humidity sensor element is disposed, and an opening that provides fluid communication between the interior and exterior of the filter housing;
• wherein the filter further comprises a filter membrane that spans the opening, the filter membrane being constructed of a hydrophobic material that allows air and water vapor to pass freely through its structure from the exterior to the interior, and that blocks liquid water and particulates from passing through its structure from the exterior to the interior, wherein:
• the filter comprises an end-cap for enclosing the sensor element at the end of the probe arm;
• the filter housing further comprises a socket with an internal tapered bore configured to permit the insertion of the terminal end of the probe arm, the filter housing comprising internal threads adjacent the socket;
• the probe arm comprises external threads on a terminal end of the probe arm;
• an O-ring is fitted into an annular groove in the probe arm adjacent the external threads;
• the internal threads of the filter housing engaging external threads on the probe arm, which permits the filter to be screwed onto the probe arm, the O-ring being compressed by the tapered bore to form a seal between the filter housing and the probe arm when the filter is screwed onto the probe arm.