11066 Searchpoint Optima Plus v2.indd - Merkantile

MAN0551.P65 Issue 06 - 03/042108M05015. COMMISSIONING5.3.2 Gas Response Testing (Multimeter) OnlyCAUTIONWithout the SHC-1 interrogator it is not possible toINHIBIT the gas detector. To avoid unintended executiveactions or alarms, it is recommended to either isolate thedetector itself or inhibit / isolate the corresponding controlcard.Functional gas testing can be performed using the multimeterto monitor the 4-20mA output:-(1) Isolate the detector by disconnecting the 4-20mAoutput from the loop terminal and connecting themultimeter to measure the 4-20mA current to either the+24V (for current sink) or 0V (for current source).Alternatively, if the control card has been isolated /inhibited, connect the multimeter in series with the 4-20mA loop.(2) Making use of either the gassing cover, or the remotegassing cell (where fitted), perform a functional gas testas detailed in Section 5.5.CAUTIONIf the 4-20mA current is not as expected, double checkthe unit’s zero, the test gas and the gassing technique.(IR gas detectors do not exhibit significant span drift andin most instances the problem is with the zero or the testgas / technique.) Only consider re-calibrating a unit whencertain that the zero, test gas and technique are correctand that the unit’s gas response is significantly out. Thecalibration procedure is detailed in Section 6.3.49