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 pathAbnormal 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 10 -7 torr and the chamber must be opened frequently. The differential seal allows pressures in the 10 -10 torr range. It is also available with an integral viewport or electrical feedthroughs.

http://www.mcallister.com/gizmos1.html

Stretching over the limit

A shortcut induced short

Great Economy ?

VacuumChamber

1

VacuumChamber

4

VacuumChamber

3

VacuumChamber

2

Turbo Turbo Turbo Turbo

BackupTurbo Station Will vent when power fails.

VacuumChamber

1

VacuumChamber

4

VacuumChamber

3

VacuumChamber

2

Turbo Turbo Turbo Turbo

BackupTurbo Station Will vent when power fails.

Mishap can multiply Small Leak

Murphy’s law strikes hard!

VacuumChamber

1

VacuumChamber

4

VacuumChamber

3

VacuumChamber

2

Turbo Turbo Turbo Turbo

BackupTurbo Station

The catastrophe happens where it can cause the most damage.

Backuppump

Consequence

1. All chambers vented.

2. One operating chamber subject todamage of several instruments:

filaments burnt, channeltron damaged, etc. Takes several weeks to recover.

Too fragile

Broken cooling connector

L

F

Improper ways to tightening bolts:

net force times large distance large strainIncreased possibility of

crack formation at the weld joint.

Proper ways to tightening bolts: net torque without net force !

Too slipperyBeware 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!

Too Slippery

Consequence of flood1. 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 2nd floor and eventually goes down to a lab in the ground floor. One photocopier in the 2nd 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.

Too hot!

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 bossySpace 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.

Too absent-minded

Improper installationviewed 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.