Calibration Vessel-5%

Use the calibration vessel in the inside/outside calibration tubes to calibrate the concrete air meter.  The curved outside calibration tube screws into the petcock. While the needle valve lever presses the petcock to open and fill the calibration vessel.  Once filled to the top, the opposite petcock opens up so the water in the tube can flow back into the base.  This procedure allows there to be 5% air in the base of the air meter in order to calibrate the gauge properly.