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| (1) Item no. | (2) Component | (3) Function | (4) Failure mode | (5) Failure cause | Failure effects | (8) System failure mode detection | (9) Compensating action | Risk analysis |
| (6) Local | (7) System | (10) SEV | (11) OCC | (12) DET | (13) RPN | (14) Recommended action |
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| 1 | AC voltage meter | Measures AC voltage | No reading | Damage | Humming | Loss of supply voltage monitoring | Humming | Fuses (main fuse and F1) to prevent circuit overloads | 3 | 2 | 2 | 12 | Replace voltmeter |
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| 2 | Solenoid valves | Open and close to control the passage of compressed air | i. Fail to open | i. Voltage failure | i. Overheating | Sample capsules cannot be transferred into the reactor and back | Valves not open or close to transfer sample capsules | Fuses (main fuse, F1, and F2) to prevent circuit overloads | 5 | 2 | 4 | 40 | Replace solenoid valve |
| ii. Fails to close | ii. Coils short or burnt | ii. Humming |
| iii. Control Spring failure |
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| 3 | Phototransistors | They switch +24 DCV when detecting dark at their base glass surface to control the solenoid valves | i. Permanently ON or OFF | i. High radiation of samples | Fail to switch (not responding) | Solenoid valves’ opening and closing cannot be controlled | i. Sample capsule into the reactor and back to the detector not being controlled | Fuses (main fuse and F1) to prevent circuit overloads | 5 | 3 | 3 | 45 | Replace phototransistor |
| ii. Fail to control | ii. Malfunction of LED |
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| 4 | Light Emitting Diodes (LEDs) | A semiconductor device that emits visible light to operate the phototransistor | i. Burnt | i. Dropper resistor failure | Fail to turn ON | i. The phototransistor cannot function | Intermittent operation of solenoid valves and phototransistors | Fuses (main fuse, F1, and F2) to prevent circuit overloads | 5 | 3 | 3 | 45 | Replace LED |
| ii. Illumination intensity reduced | ii. Supply voltage reduced | ii. Light flickering | ii. Solenoid valves cannot be controlled |
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| 5 | Switches | Isolate and deisolate load(s) from the power supply | i. Fail to open | i. Contact dirty/corroded | i. Overheating | i. Intermittent operation of loads | i. Loads not operating | None | 6 | 2 | 2 | 24 | i. Replace switches |
| ii. Fail to close | ii. Release spring failure | ii. Arcing | ii. Intermittent measurements | ii. Abnormal measurements | ii. Can also use electrical circuit breakers |
| iii. Visual smoke or arcing |
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| 6 | Fuses | Prevent overcurrent | i. Blow prematurely | i. Overcurrent | i. Blown fuse | i. System shutdown | i. Visual smoke | Fuses (F1 and F2) to prevent circuit overloads | 6 | 3 | 1 | 18 | Remove the overload and replace fuse with spare. Consider the fuse rating |
| ii. Fail to blow upon overcurrent | ii. Improper fuse selection | ii. Arcing across fuse electrodes | ii. System malfunction | ii. Loads not operating |
| iii. Fuse burned into place | iii. System power overload | iii. Indication and warning lights OFF |
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| 7 | Relays (coils and contacts | Close relay contacts when energized. The contacts engage and disengage the solenoid valves to the circuit | i. Coil short circuit or burnt. ii. Fail to close (engage) | i. Contact dirty/corroded | Overheating | i. Circuit overheating | i. Voltage measurements not as expected | Fuses (F1 and F2) to prevent circuit overloads [6] | 5 | 3 | 3 | 45 | Replace relay and any blown fuse(s), wire(s), or connector(s) |
| iii. Open (disengage) | ii. Release spring failure | ii. Blown fuse | ii. Visual smoke |
| iii. Loss of power supply to operate the solenoid valves | iii. Loads (solenoid valves) not operating |
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