Fire extinguisher

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| rowspan=2 | Shredding cutoff time-delay
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| rowspan=2 | Top Assembly
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* Turns motor on and keeps motor temporarily turning after paper has passed through to ensure complete shredding
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* Contains the triggering mechanism for the extinguisher
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| Electrical failures: Short circuited
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| Top handle breaks
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| rowspan=2 | Product ceases to function reliably.  Shredding no longer possible.
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| Cannot depress pin to trigger the extinguisher
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| 8 || Intense heat and/or vibrations loosen connections, resulting in intermittent operation || 4 || Run under extreme working conditions || 3 || 96 || Add solder to strengthen connections. Add dampening to decrease effect of vibrations || Switch manufacturer prior to purchase || - || 8 || 3 || 3 || 72
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| 10 || Extinguisher falls or is hit by an object || 1 || Test durability of top handle || 5 || 50 || Increase thickness of plastic. Use Stronger Plastic || Design Engineers || - || 10 || 1 || 5 || 50
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| Mechanical Failures: Creep. Fatigue. Deformation. Shear.
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| Bottom Handle breaks
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| 8 || Flat metal spring fatigues leading to fracture. Thermal deformation from heat generation. Plastic deformation from shredding unapproved items || 4 || Compress and expand spring repeatedly and under extreme conditions || 3 || 96 || Treat metal to strengthen. Increase thickness of spring. || Switch manufacturer prior to purchase|| - || 8 || 2 || 3 || 48
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| Uncomfortable to hold/use
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| 3 || Extinguisher falls or is hit by an object || 1 || Test durability of bottom handle || 5 || 15 || Increase thickness of plastic. Use Stronger Plastic || Design Engineers || - || 3 || 1 || 5 || 15
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| Helical Blade || Mechanical Failures: Shearing. Fatigue. Thermal. Wearing. || Fracture of blade will result in inefficient, but continued, function. Bending of blade can result in wear against other blades, which can also result in a chain reaction leading to complete failure. || 7 || Bending and shearing can result from shredding unapproved items. Fracture and malfunctions can also result from malfunctions of other components such as the main shaft or gears. || 4 || Shred unapproved items. Work at high rpm. Shred lots of paper and/or credit cards || 5 || 140 || Thicker blades for strength. Smaller opening so unapproved items are harder to fit. || Blade stamping department || - || 7 || 2 || 5 || 70 ||
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| Valve Pin|| Does not seal properly || Could result in slow loss of pressure from the canister, leaving the extinguisher useless || 10 || Rubber gaskets may not fit on the pin correctly resulting in an ineffective seal || 3 || Test seals performance at large range of pressure|| 2 || 60 || Find a better way to secure gasket to pin || - || 10 || 3 || 2 || 60 ||
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| Canister || Over pressurized || Could result in unexpected rapid decompression, rendering the extinguisher useless and possibly exploding  || 10 || Canister is over pressurized  || 3 || Test canister to see its maximum pressure || 2 || 60 || Increase safety factor by increasing the maximum pressure rating of the canister|| - || 10 || 3 || 2 || 60 ||
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Revision as of 21:58, 23 September 2007

Automated fire extinguisher



Item & Function Failure Mode Effects of Failure S Causes of Failure O Design Controls D RPN Recmd Actions Responsibility & Deadline Actions Taken S* O* D* RPN*
Mounting Bracket Extinguisher falls off bracket Compromises structural integrity of the canister and triggering mechanism. 8 Canister not secured to bracket 5 Secure canister to bracket 5 125 Add strap to make sure canister is secured to bracket Design Engineers - 5 5 5 125
Bracket falls off wall Compromises structural integrity of the canister and triggering mechanism 5 Bracket not screwed securely to wall 5 Test mounting bracket on different types of walls 3 75 Treat motor axis to add strength Design Engineers - 5 5 3 75
Pressure Gauge May not display proper reading. Empty extinguisher could read as full. 10 Pressure from canister not correctly transmitted to gauge. 2 Test gauges by slowly discharging canister 3 50 Increase space around the pressure gauge in order to ensure that the gauge correctly reads the pressure in the canister Design Engineers - 10 2 3 50
Safety Pin Pin breaks and cannot be removed If the pin cannot be removed, the extinguisher will not discharge 10 Pin is thin, may snap if not pulled out straight 3 Test strength of pin 2 50 Make pin thicker. Use stronger plastic. Pin Manufacturer - 10 3 2 50
Top Assembly
  • Contains the triggering mechanism for the extinguisher
Top handle breaks Cannot depress pin to trigger the extinguisher 10 Extinguisher falls or is hit by an object 1 Test durability of top handle 5 50 Increase thickness of plastic. Use Stronger Plastic Design Engineers - 10 1 5 50
Bottom Handle breaks Uncomfortable to hold/use 3 Extinguisher falls or is hit by an object 1 Test durability of bottom handle 5 15 Increase thickness of plastic. Use Stronger Plastic Design Engineers - 3 1 5 15


Valve Pin Does not seal properly Could result in slow loss of pressure from the canister, leaving the extinguisher useless 10 Rubber gaskets may not fit on the pin correctly resulting in an ineffective seal 3 Test seals performance at large range of pressure 2 60 Find a better way to secure gasket to pin - 10 3 2 60


Canister Over pressurized Could result in unexpected rapid decompression, rendering the extinguisher useless and possibly exploding 10 Canister is over pressurized 3 Test canister to see its maximum pressure 2 60 Increase safety factor by increasing the maximum pressure rating of the canister - 10 3 2 60


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