A sample tube entry port for an automatic chemical analyzer supports individual draw tubes that are manually delivered to the analyzer at a sample access station. The entry port facilitates removal of samples by the pipette without exposing operating personnel to accidental contact with liquid materials in the draw tube. To accommodate draw tubes of differing heights, the apparatus includes a stripper that is selectively locked onto an elevationally movable ram carrying a receptacle for receiving a draw tube. A spring-biased tube clamp urges each draw tube against guides within the receptacle to center draw tubes of differing diameters. During operation of the apparatus, the receptacle is first lowered to a predetermined elevation, then raised to an intermediate elevation at which a draw tube closure is properly positioned for placement of the stripper immediately adjacent to its upper surface. The stripper is locked relative to the ram in this elevational relationship, which is maintained as the closure is impaled on the puncture tube and/or the pipette that accesses the contents of the draw tube.