A sampling system for collecting periodic composite and/or non-composite samples of vaporized gas during a transfer process from a vaporizer of a cryogenic hydrocarbon liquid including 1) a direct sample pathway to a gas analyzer for instantaneous, real-time vaporized gas analysis, 2) a speed loop pathway for directly collecting fresh vaporized gas samples for subsequent analysis, and 3) a composite sample pathway including a pressurized sample accumulator for collecting a plurality periodically obtained samples of a select volume during the transfer process to create a composite sample of the vaporized gas.