Abstract: A sampler for communicating with the interior of a vessel containing a slurry under pressure extracts a sample of the slurry from the vessel and conveys the same to a point of collection. The sampler includes a conduit having an inlet for communication with the interior of the vessel and an outlet to the exterior of the vessel, and a valve for selectively establishing and interrupting communication between the conduit inlet and the interior of the vessel. When communication is established, a sample of slurry flows into the inlet, through the conduit and to the outlet for collection, and when communication is interrupted a source of flushing liquid is coupled with the inlet to flush the conduit clean of residual sampled slurry. By virtue of introduction of flushing liquid through the conduit when slurry is not being sampled, residual slurry is prevented from settling out and/or hardening in the conduit and clogging the sampler.