Baker Hughes Masoneilan 12400 Series Instruction Manual & Safety Manual

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Baker Hughes Masoneilan 12400 Series Instruction Manual & Safety Manual Manual pdf 50 page image

48 | BHGE ® 2017 Baker Hughes, a GE company. All rights reserved.8.4.4.CHARACTERISTICSDevice Level (SIL) Unit type HFT sd su dd du SFF12400 SeriesDigital LevelInstrumentB 0 0 FIT 192 FIT 575 FIT 72 FIT 91.48.5. SAFETY FUNCTIONThe Safety Function of the 12400 series Digital Level Transmitter must be to monitor the level or interface of a liquid andtransmit a 4-20 mA analog signal within the measurement safety accuracy. It includes the whole hardware and softwaremeasurement chain from the displacer through the torque tube and the electronic board to the primary analog output signalAO_1.8.6. PROOF TESTAccording to section 7.4.3.2.2 f of IEC 61508-2, proof tests must be undertaken regularly to reveal dangerous faults which areundetected by diagnostic tests. This means that it is necessary to specify how dangerous undetected faults, which have beennoted during the FMEDA, can be detected during proof testingThe test intervals necessary for this purpose are defined in the calculation of the respective safety loop.Tests must be conducted by the manufacturer or an authorised person duly trained on the instrument and SIS operations.Recommend Proof testStep Action1 Bypass the safety function and take appropriate actions to avoid a false trip and any safe actionsagainst dangerous atmospheres.2 Inspect the instrument for dirty or clogging parts, adequate wiring, correct mounting of endconnections and other physical damage.3 Examine the torque tube and the displacer to detect corrosion or leaks (replace if necessary).4 Observe the tightening torques for the nuts and studs.5 Check the Bias spring position is correct.5 Use HART communications to retrieve any diagnostics and take appropriate action.6Send a HART command to the transmitter to go to the high alarm current output and verify that theanalog current reaches that value.This tests for compliance voltage problems such as a low loop power supply voltage or increasedwiring resistance.7Send a HART® command to the transmitter to go to the low alarm current output and verify that theanalog current reaches that value.This tests for possible quiescent current related failures.8Perform a five-point calibration check of the displacer and transmitter over the full working rangeusing the process fluids(s).If the calibration check is performed by any means other than the fluid(s) acting on the displacer, thisproof test will not detect any failures of the displacer.9 Lock the settings by adjusting the hardware lock jumper position10 Remove the bypass and otherwise restore normal operation.