PhD6 Multi-Gas Detector Reference Manual - Honeywell Analytics

educed oxygen level in the calibration gascylinder allows the oxygen sensor’s response tobe tested in the same manner as the toxic andLEL sensors.If the O2 sensor fails to register a reading below19.5% during the gas calibration, the display willshow “Check O2 Sensor Response”. PressMODE to continue.If the oxygen sensor fails to register the drop inoxygen during the gas calibration while beingchallenged with calibration gas containing lessthan 19.0% oxygen, it should be considered outof tolerance and retired from service immediately.See section 5.2.4 under Gas Values for moreinformation on the O2 sensor check.A sensor that cannot becalibrated or is found to be out of toleranceshould be replaced immediately. Aninstrument that fails calibration may not beused until testing with known concentrationtest gas determines that accuracy has beenrestored, and the instrument is once again fitfor use.Possible causes and remedies for oxygensensor failure:1. Calibration gas cylinder does not contain areduced level of oxygen. Verify that thecylinder contains less than 19.0% oxygen.To challenge the oxygen sensor withoutcalibration gas, hold your breath for about 10seconds and then slowly exhale directly ontothe face of the sensor (in the same way youwould attempt to fog up a piece of glass). Ifthe descending oxygen alarm is set to 19.5%,the instrument should go into alarm after afew seconds. If the oxygen sensor fails to gointo alarm during the exhalation test, theoxygen sensor must be replaced.2. Oxygen sensor has just been replaced andhas not had time to stabilize.3. Oxygen sensor failure.4.4 Special Calibration Instructionfor NDIR CO 2 sensorThe Infrared CO 2 sensor requires two differentgas sources for full calibration. The reason forthis is that it is effectively impossible to zerocalibrate a CO 2 sensor in ambient air becausethere is an unknown and varying amount ofbackground CO 2 present in the atmosphere.4.4.1 CO 2 Sensor True ZeroTo determine if the CO 2 sensor requires zerocalibration, connect the PHD6 to a cylinder ofcalibration gas that contains 0.00% CO 2 while theinstrument is in normal operation.If the reading shows 0.00% CO 2 , then the CO 2sensor does not require zero calibration.Disconnect the cylinder from the PHD6.If the reading shows anything other than 0.00%CO 2 , leave the calibration gas on and press theMODE button three times within two seconds toinitiate the zero calibration sequence. PressMODE again when prompted to begin the zerocalibration. Instruments equipped with a CO 2sensor will automatically show the message“Press MODE if applying Zero Air” with another 5-second countdown. Press MODE again to beginthe true zero calibration and follow theinstructions given on the screen. Once the zerocalibration is complete, remove the zero aircylinder from the instrument and proceed to thegas calibration (if necessary).The gas calibration of the CO 2 sensor isperformed during the standard gas calibrationthat is described above in section 4.3. The PHD6will automatically prompt the user to apply theCO 2 calibration gas during the standard gascalibration sequence.4.5 Special Calibration Instructionsfor NDIR-CH 4 SensorIn many ways, the NDIR-CH 4 sensor used in thePHD6 is similar to a hot bead LEL sensor. Forthe purpose of calibration, they are very different.While LEL sensors can be calibrated with anumber of other gases when properly configured,The NDIR-CH 4 sensor must be calibrated withmethane to the exact amount shown on thecalibration gas cylinder. (This is different fromLEL sensors, where methane may be used forcalibration, but is often done at a scale thatmakes the readings mimic those given by aspecific amount of propane or pentane).The NDIR CH 4 sensor inthe PHD6 must be calibrated using methane(CH 4 ) calibration gas at the actual amountshown on the cylinder. The defaultcalibration gas value for the NDIR-CH 4 sensoris 50% LEL. The appropriate calibration gaslevel for the 50% LEL default calibration gassetting is 2.50%/vol. CH 4 . Use ofinappropriate calibration gas may lead toinaccurate and potentially dangerousreadings.5. Menu OptionsThe PHD6 operating firmware includes two menuoptions: the Basic Menu and the Main Menu.5.1 Basic MenuThe Basic Menu is a shortened version of theMain Menu that offers immediate access to a fewkey functions including:PID On/Off (enable or disable the PIDsensor)Displayed VOC (select the targetcompound for the VOC sensor)Contrast (display’s light vs. dark setting)22