2 1 0 60 26M NAA | XSER IE S G 5 | 125Connect the calibration standard to the calibration test port.Apply pressure to the next preferred verification pressure.After the current reading stabilizes, enter the pressure value from the calibration source,and click OK.After all the static pressure markers have been set, determine if calibration is required. Return themanifold to service before exiting Calibration mode if more calibration is not required.11.1.3 Calibrating static pressureA three- or five-point pressure method is used to calibrate the flow computer SP cell. Differentpressures are applied to the cell from a known, traceable source with resultant pressure valuesentered into the flow computer using PCCU32 software.IMPORTANT NOTE: The flow computer uses an absolute static pressure (SP) cell. Absolutepressure measures the referenced pressure to a vacuum or sealed pressure. This differsfrom a gauge cell which measures the referenced pressure to the atmosphere. Since the SPcell is an absolute device, it always measures the true pressure, relative to a vacuum orsealed chamber. As such, when vented, it measures the true barometric pressure. For otherpoints of calibration, add the reading of the PSI and the barometric pressure to arrive at thePSIA. Once this has happened, enter the reading.11.1.3.1 Absolute vs. GaugeThe initial calibration point should be completed under vented conditions. Additionally, when this takesplace, ensure that the barometric pressure reading (in PSI) is used as the initial point.When operating in PCCU32 Absolute mode, other points of calibration are determined by adding thePSI reading and the barometric pressure to arrive at the PSIA. Enter this reading.Operating in PCCU32 Gauge mode, the readings may be entered as read. Upon completion, abarometric pressure reading is entered.11.1.3.2 Calculating PSITo convert barometric pressure measured in inches of mercury to PSI, perform the followingcalculation:Barometric Pressure (inHg inches of mercury) * 0.49115 = Barometric Pressure in PSI11.1.3.3 CalibrationWhile performing the following procedures, wait for the flow computer display to stabilize beforeentering the new values. If the flow computer is not in Calibration mode, the display will notnecessarily match the applied cell pressures.Select Calibration on the tool bar to place the flow computer in Hold mode.Select the measurement tube in the navigation tree.On the Calibration tab, select SP from the Calibration drop-down menu.Select either a 3- or 5-point calibration from the corresponding drop-down menu.Select the range (URL) of the transducer SP pressure cell. The range should agree with thetag attached to the transducer.Define the SP display value: Absolute or Gauge.IMPORTANT NOTE: Selecting Absolute will display the value with the barometric pressureadded in. If calibrating in Absolute mode, the barometric pressure is the low calibrationtarget point. Subsequent values require that the barometric pressure be added to the valuebefore the value is entered.Selecting Gauge will display values in gauge pressure. Subsequent values require that theentered values be in gauge pressure.Enter the barometric pressure in the bottom field before proceeding.Verify that the vent valve is closed.Open both the high and low equalizer valves.
