Instrumentation engineering root cause analysis of mechanical temperature indicators (MTI) problems and solutions.
Article Type: | Root Cause Analysis (RCA) |
Category: | Instrumentation |
Equipment Type: | Sensors |
Author: | S. Raghava Chari |
Note: This root cause analysis (RCA) is from real-time scenarios that happened in industries during the tenure of two or three decades ago. These articles will help you to improve your troubleshooting skills and knowledge.
Mechanical Temperature Indicators (MTIs) – filled system, bi-metallic, capillary type, etc. posed the below-listed problems:
Relenting to the author’s appeal he did not shutdown the plant giving two days to resolve the issue. Nightlong thinking showed a way out.
The author gave the operators a trolley-mounted rush-bought moving coil temperature indicator connected to high temp insulation Iron Constantan extension lead (EL). He crimp jointed the wire’s other end.
He named it Extension Lead Thermocouple (ELTC). Operators inserted the ELTC in each TW and read the temperatures. This temperature arrangement mollified the plant superintendent temporarily.
Seeing the satisfied operators, the author decided discarding all MTIs and to provide Thermocouples connected via selector switch Potentiometric Temperature Indicator for all temperature measurements.
He called these Temperature Monitoring Stations (TMS fig 2). Two below given constraints threatened the implementation:
Thermocouple (TC) Selector Switches (TSs) > 6 months delivery; The author resolved this thus: He rush-procured 2‑pole 2-throw telephone switches in 15 days.
The shop made the pedestal-mounted box as per his sketch within the time, Instrument crew under his guidance assembled and wired the telephone switches in a week. Thus constraint 1 vanished
Thermocouple Assemblies long delivery times: The author resolved this thus: He developed a homemade Extension Lead Thermocouple (ELTC).
Instrument crew made these thus:
CO2 and NH3 piston compressors’ TMSs were in service within 3 weeks of the project concept.
Impressed by the TMS offered convenience, uninterrupted availabilities, and savings all plant superintendents clamored for it.
The author and the instrument crew met the challenge and pleased all by commissioning the 9 more strategically located TMSs.
Extension Lead Thermocouples (ELTCs) advantages are:
Benefits Realized are:
Author: S. Raghava Chari
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