An ultrasonic flow meter for measuring the flow of a fluid through a pipeline comprises a spool piece including a throughbore and a transducer port. The transducer port extends along a central axis from an open end at the throughbore to a closed end distal the throughbore. In addition, the flow meter comprises an acoustic transducer disposed in the transducer port. The transducer includes a piezoelectric element. Further, the flow meter comprises a drain port in fluid communication with the transducer port. The drain port is axially positioned between the open end and the closed end of the transducer port. Still further, the flow meter comprises a drain conduit having an inlet end coupled to the drain port and an outlet end opposite the inlet end. The drain port is configured to drain a liquid from the transducer port into the inlet end of the drain conduit.