Presentation on theme: "Murphy’s law Everything that can go wrong will go wrong. Especially true when we explore the unknown."— Presentation transcript:
Murphy’s law Everything that can go wrong will go wrong. Especially true when we explore the unknown.
Murphy’s law Always strikes to make the biggest damage! Painful Examples: 1.Too long. 2.Too late to know. 3.Too short. 4.Too slippery. 5.Too hot. 6.Too cold. 7.Too complicated. 8.Too absent minded. 9.Too tired. Wise people learn from someone else’s pain.
Two mm too long
Two mm too long.
Two mm too long
Normal welding path Abnormal part
Cracked welding path
Closeup of the cracks
Cost of that negligence An expensive gate valve. One whole week of effort to find the problem. A lot longer to solve the problem. Delayed graduation by 3 month.
More perspective is better.
Small details sometimes count big Welding bead is likely to cause reduced ID, but of which tube? A B C
Intricacy of gate valves “UHV” compatible? Vapor pressure of the lubricant counts! Do pay attention to small prints! Sometimes it counts a lot! Too late to know
Why you need a RGA
Too late to know (2) This differentially-pumped quick door is really handy for quick access to large systems where the base pressure is lower than torr and the chamber must be opened frequently. The differential seal allows pressures in the torr range. It is also available with an integral viewport or electrical feedthroughs.
Stretching over the limit
A shortcut induced short
Great Economy ? Vacuum Chamber 1 Vacuum Chamber 4 Vacuum Chamber 3 Vacuum Chamber 2 Turbo Backup Turbo Station Will vent when power fails.
Vacuum Chamber 1 Vacuum Chamber 4 Vacuum Chamber 3 Vacuum Chamber 2 Turbo Backup Turbo Station Will vent when power fails. Mishap can multiply Small Leak
Murphy’s law strikes hard! Vacuum Chamber 1 Vacuum Chamber 4 Vacuum Chamber 3 Vacuum Chamber 2 Turbo Backup Turbo Station The catastrophe happens where it can cause the most damage. Backup pump
Consequence 1. All chambers vented. 2. One operating chamber subject to damage of several instruments: filaments burnt, channeltron damaged, etc. Takes several weeks to recover.
Broken cooling connector
L F Improper ways to tightening bolts: net force times large distance large strain Increased possibility of crack formation at the weld joint.
Proper ways to tightening bolts: net torque without net force !
Too slippery Beware of cooling connections. Bad pratices cause lots of flood. Never use teflon tape to compensate for mismatching hose diameter! Absolutely bad idea! The damage could be huge!
Consequence of flood 1.The connection under pressurized water very slowly slipped and finally break loose near midnight. The pressurized cooling water squirted toward a running PC. In particular, onto and destroyed an interface board of a CCD camera. Unfortunately, the manufacturer of that expensive CCD had already gone out of business, and no replacement card can be found. The expensive CCD thus becomes useless. 2.The water accumulate on the lab floor and leaked through the cracks, “showering” the lab below on 2 nd floor and eventually goes down to a lab in the ground floor. One photocopier in the 2 nd floor lab get soaked. Fortunately, after taking it apart and cleaned everything, it goes back to work. Hindsight: Use only as much cooling as is needed. We now use fishtank circulator plus a water container. The water pressure is so much smaller and the total amount of water is limited.
The burnt pump
Is heat from baking the last straw?
Hindsight Exactly the same thing happened in Prof. Jim Lin’s lab. “Alcatel” has found the problem and issued a recall. (They used a cheap but unreliable capacitor!) “Alcatel Taiwan” has not informed us of the recall. This is really unwise! The fire could become a major disaster if not found early. Then they will be responsible for much bigger loss. “Alcatel Taiwan” has provided free repair of the pump. It is your judgement whether that can repair their reputation? Pump make and model: Alcatel: Pascal 2015SD
Prevention ? IAMS has since bought a far infrared thermal camera for inspection of the lab or malfunctioned instrument. It’s quite some experience to see the world from a totally different wavelength! You should ask your lab’s safety officer to borrow it and record images of your instrument while it is still normal.
Too bossy Space Shuttle Challenger. The weather can’t be too cold at Florida? If you are not fuuly convinced, discuss with your boss! (unless you prefer to get into big trouble).
Two units are too confusing. Mar’s rover Team work needs communication. Always ask questions! If you have to do it, you deserve a satisfying answer.
Improper installation viewed from the inside of the chamber
Too tired. The catastrophic end of a turbo.
Be prepared. If we run a Turbo pump long enough, it’s going to crash sooner or later. How do we handle such situation? Get the research done and graduate before the turbo quit. Leave it to the boss? What about your boss run out of cash for the next 6-month?
Contain the butterfly. Don’t give it a chance to amplify. 假如 項羽 當年渡過烏江 ? 李清照 《夏日絕句》 生當作人傑，死亦為鬼雄。 至今思項羽，不肯過江東。 Control the damage!
Go for it. Exercise your own Judgment Resist temptations Do it right If you are innovative, you will encounter un-anticipated surprises. With all the small mishaps, life Goes On! And I hope you all make big discoveries sooner or later.