Prior to taking the measurement, review the detector tube instruction for use to familiarize yourself with the operation of the tube. The instructions will specify the number of pump strokes and the color change. The arrow on the tube indicates the direction of flow. Prepare a Uniphos water vapor tube by breaking the tips of the tube and inserting the tube into the pump with the arrow on the tube pointing toward the pump inlet. Insert the tube into the hole on the side of the sampling bulb to approximately 1.5 to 2 inches (4 to 5 cm). Align the red dots on the barrel of the pump and the piston handle and pull the handle all the way back. The handle will engage and the pump cycle will begin to pull 100 ml through the tube with each pump stroke. Upon completion of the required number of strokes, remove the tube from the sampling bulb and read the stain on the tube.