Kamikaze Hot Plates Hot plates that heat when off or heat too much.

Transcription

1 Kamikaze Hot Plates Hot plates that heat when off or heat too much. ation-and-fire-from-malfunctioning-lab-stirrerhot-plate-part-2- Take-Note-The-dividends-from-simultaneous-excellence

2 Hot Plate Fires in MIT labs Fires occurred in July 2009, April 2010, & Feb Examination by the Department of Chemistry s Senior Electronics Technician, led him to the conclusion that Corning PC-35 and PC-351 hotplates were inherently unsafe based on their design fire from unattended process involving heating a sugar solution fire from hot plate accidently turned on when items placed in front of it. Have there been others?

3 Runaway Hot Plate Survey Joint project by UPenn and Oak Ridge. Hot plate surveys sent to members of EHS-related lists (DCHAS, CSHEMA). Purpose of survey: To collect anecdotal information on hot plate failures due to malfunction. To better understand the relative prevalence of these malfunctions, what types of malfunctions are occurring, why they occur, and the consequences of the events, including lessons learned.

4 Runaway Hot Plate Survey Results 25 responses 17 respondents described spontaneous-heating malfunctions, runaway-heating malfunctions, or both. Total number of events = events reported to be reproducible or otherwise confirmed as the cause of the unintended heating event

5 32 reported incidents a few examples June 29, 2005 Power switch failed, resulting in fume hood fire. Lawrence Berkeley National Laboratory March 2015 Corning PC 420D hot plate unexpectedly heated to high temperature while heat dial was in the off position. University of Pennsylvania May 12, 2012 Hot plate was left on and ignited combustible materials in the laboratory. University of Pennsylvania July 2014 Fire from hot plate that was plugged in overnight but not turned on. University of Pennsylvania January 2015 A hot plate observed with the Hot Surface light on while hot plate controls were in off position. Oak Ridge National Laboratory

6 What makes a hot plate unsafe? Lack of temperature feedback from plate surface or heating element. Glitch in microprocessor that tells hot plate not to heat. Failure in semiconductor that controls the heat when hot plate is on.

7 Hot Plates With Reported Incidents Brand Model Spontaneous Runaway Other/Notes Heating Heating Corning PC-35 X No temperature feedback. PC-351 X No temperature feedback. PC-200 "Off" does not disconnect power from heating element. PC-220 X "Off" does not disconnect power from heating element. PC-320 X PC-400D X PC-420 X X "Off" does not disconnect power from heating element. PC-420D X X "Off" does not disconnect power from heating element. VWR 7x7 Aluminum top (no model # given) X Troemner Fisher Chemglass Professional Ceramic7x Advanced Ceramic 7x7 Isotemp H/ H Optimag-St CG / CG / CG-1993-T-50 X MIT evaluated 2 of their Troemner hot plates and found safety hazards based on the design and manufacturing practices. "Off" does not disconnect power from heating element. MIT electronics tech verified that this model heated to 300 within a min even though it was off Cimarec* SP46925 X X No temperature feedback. H-4954.xx X IKA X Errors out easily; prone to overshoot when heating Sold under Thermolyne, Barnstead/Thermolyne, and Fisher names depending on age.

8 What makes a hot plate safer? Circuitry is designed to be safe Automatic overtemperature monitoring (fail safe) Separate on/off switch from the heat/stir controls Hot surface light

9 Replacing Unsafe Hot Plates Trade-in program through Fisher Fisher Cimarec+ (safer than older Cimarec model) MIT has verified the safety features. Fisher has special pricing for a certain time period to encourage labs to replace their unsafe hot plates. Quote and instructions are on EHS site

10 THIS BIN IS ONLY FOR UNSAFE HOT PLATES & STIRRERS 1 st Decontaminate Bleach for biologicals Simple Green for chemicals 3 rd Remove or cut cord Make hot plate unusable 2 nd Complete Decon sticker (get stickers from your EHS Coordinator) Stick it on the top 4 th Put Hot Plate & cord In this bin, NOT regular recycling bin

11 Recycle your old hot plates in the large or small totes with the hot plate signs

12 Recommendations Purchasing hot plates Avoid combination plates if only stirring is needed. Buy UL listed or other Nationally Recognized Testing Lab Replace hot plates manufactured prior to 1984 Operations--Best Practices Perform heating functions only when personnel are monitoring heating (Watch what you heat) Cut power when not in use Newer models--use the on/off switch Older models--unplug

13 Recommended Practices Make your work area safer >6 inches Keep plastic, paper, cardboard, etc. at least 6 inches away from hot >2 feet Keep flammable solvents 2 feet away from hot plates, even when hot plate not in use. (on all sides, shelves/monkey bars)

14 Recommended Practices Clear shared work spaces of equipment and reagents when done with procedure. Always pick hot plates up from the base to prevent hand burns. Don t put hot glassware directly on the colder lab bench or on the surface of the fume hood. The glass shards will fly everywhere.

15 Questions?