New blog!

We have a new blog, and I mean "we"! You're all invited to participate. Check it out at http://oui-sez.blogspot.com/.

See you there!

Rewound.

Today I declare "TwiDurf in NYC" to have officially ended, except for comments and emergency posts. Twila says she wants to start a new blog along "He Sez, She Sez" lines, but we don't have any real ideas yet about what to talk about.

This has been a lot of fun, and thanks to all of you!

P.S. Jan, are you getting my email?

Rewind.

It just occurred to me that I really don't like writing about myself, and if you aren't already bored with it you soon will be, I promise. The problem is that there are thousands of stories a day in New York and the last story in Loveland was recorded last year.

I thought I might try to keep this blog going, but Twila says she's through and I don't have anything to write about. If you have any suggestions about how to solve this conundrum, please send them to the email address of this blog, whatever it is.

I, Durfbot.

A couple of years ago when I, somewhat reluctantly, became retired, I was pleasantly surprised by how much I enjoyed it. The pay is horrible, but I really like being able to do whatever I want whenever I want. I did not experience a loss of identity, as I had when I was unemployed for several months in 1980. I could spend hours reading newspapers, then more hours flicking away the day. My failure to produce anything useful did cause some guilt, but I was raised Catholic, so I'm used to that.

I wasn't surprised that I didn't write a novel or create a best-selling iPhone application. Throughout my life I've worked hard for others, but have almost zero personal ambition. I am content to absorb whatever knowledge and pleasure flows my way.

The NuSTAR job was a wonderful experience. Twila and I had a great time, and both of us fell in love with New York City. Getting up in the wee hours and working six days a week was kind of annoying, but it wiped away any guilt I might have felt by goofing off the rest of the time. Not to mention that I was making more money than I'll probably ever make again, or at least until I finish that iPhone app.

Alas, all good things must come to an end (as must all bad things). The time passed quickly, and in a seeming flash it was time to return home to Colorado. That was fine with me. As a bobbing apple on the sea of life, I am used to change. But, there was work to be done. Twila was already in Loveland, so it was up to me to pack the rest of our stuff and get it home. That's when robot mode started.

If I *have* to do something, I just do it. It began gradually and accelerated as the deadline neared. I packed 22 boxes and took them to UPS.

Maybe I need to say something about that. Twenty-two boxes is a lot, but Twila and I weren't able to carry much to NY. Instead, we bought what we needed when we arrived. Before she left NY, Twila shipped back about 6 boxes, including a lot of items related to her business. I shipped many more boxes for two reasons. One is that I had to ship the household items that we shared. The other is that I bought more things in NY. After all, I was making money, and what is money for?

You all know what moving is like. To sum it up, "no fun". As the days wore on, I wandered around our apartment zombie-like, stuffing boxes and cleaning and absolutely determined to do a good job.

That lasted until Twila arrived to drive home with me, and even into the next morning. Then we were on the road. It was as fun a trip back as a non-recreational driving trip can be. But driving up to 10 hours a day for 3 consecutive days is tiring and not without stress. Blessedly, at last we were home.

Then there was the initial unloading of the car and unpacking of boxes and suitcases. After that there were the 4 boxes that I'd shipped first. On Tuesday 10 more boxes arrived (many of them squished and ripped). And today the final 8 boxes appeared.

In addition to the unpacking and trying to figure out where to put everything, I had to register my car, reinstall computer equipment, take care of house maintenance issues, and all the other things that had piled up. I think it will be a couple of weeks, at least, before I can return to my life of useless idleness.

In the meantime, I am a robot. I don't even think about how much I have to do, I just do it. I go from task to task in a semi-trance, almost numb to the exhaustion that's built up over the last few weeks. New hassles don't bother me, they just get put on the pile. I have become a machine.

Brilliant (until 1st round) brackets.

Durf's

Twila's

The beagle has landed.

A very busy day... well, several... lies ahead, but I think it appropriate to take a moment to tell you that last night we arrived safely in Loveland. Besides, my preferred title for this post gives me the opportunity, if not obligation, to name my Outback - Snoopea.

Leaving Tarrytown was a ginormous feat. We arrived there in June with everything packed into my Prius. Before leaving, Twila shipped via UPS 6 medium-sized U-Haul boxes back to Loveland; I managed to pack and ship 22 (mostly medium, some small). Then I folded down the seats in the Outback, smiled at the large amount of space available, and proceeded to pack it completely. It was so full that in the event of a front collision numerous projectiles would have flown forward in a terrifyingly hazardous manner. In the end we couldn't even stuff in a small but nifty waste paper basket that both of us fancied, and several non-food items were stuffed in our cooler (which we forgot to ice).

After final jamming on Friday morning, we dropped the keys off at the manager's office and hit the road. Well, tapped the road might be a more apt description. A major artery near us had been closed because of flooding, and the street outside the apartment complex was filled with bumper-to-bumper stop-and-go westbound traffic. Cleverly, we turned east and circled around most of that traffic, only to not-so-cleverly miss our turnoff. Searching for another way around the mess we ended up in Dobbs Ferry, which at the time could more accurately be described as No Man's Land. To cross the Hudson meant a huge amount of traffic in either direction from there, so we adapted by getting lattes.

Finally we did reach the Tappan Zee bridge and our long trip began. It was annoying at first, because the Outback only had 300 miles on the odometer, and use of cruise control was advised against during the 1000-mile break-in period. Being virtually wed to the concept of cruise control, I found having to use my foot to control the accelerator while simultaneously having to monitor speed to be painfully retro. I did get to 800 miles before starting to cheat, though.

We spent the first night in Youngstown, Ohio, and the second in Altoona, Iowa. We arrived in Loveland at 6 PM Sunday, though with the changes in time zone combined with the switch to daylight saving time, it could have been 5 or 7:30 PM.

Hopefully Twila will overcome her blogophobia long enough to fill in some of the blanks. I'm off to rediscover my home.

NYC, I hardly got to know ye.

I just started the last dish laundry and am about to disconnect the cable modem to return it. Twila will be taking off in 1 hour, if all goes well.

Catch y'all on the flip-flop!

Vacuum doesn't suck, Part 3.

I apologize for scooting through this thread, but Twila and I will be driving home on Friday and things have busified. It would be fun (for me, maybe not for you :p ) to talk about other kinds of vacuum pumps, but I'll jump ahead to leak detection.

With luck, our vacuum chamber pumped quickly down to high vacuum. But luck? - hah! Suppose we can't pump to a low enough vacuum, or suppose the vacuum rises too quickly when we close the pump valve? We have a leak, and the fun begins.

Remember that we aren't talking about big globs of air in the chamber, we're talking about scattered molecules. It doesn't take many new ones to affect the pressure. Gas molecules are very small and there will always be a few getting in somehow, but not all vacuum leaks are leaks.

I'm at a machine that is not reaching the required vacuum. Once I've verified that the plug is in the wall, the pumps are running, and the ON/OFF switch is in the ON position, three possibilities pop into my cranial vacuum:
1) There is a leak. Gas molecules are getting into the chamber from the outside.
2) Outgassing is occurring. Some things, such as water vapor, are extremely difficult to pump. Or there might be a contaminant in the chamber that is releasing molecules.
3) There is a virtual leak. There might be, for example, a tiny crack somewhere inside the chamber. At atmospheric pressure, air eventually fills the crack. When the chamber is pumped, air leaks from that crack at a slow rate that mimics a leak from the outside.

There are ways to diagnose and deal with #2 & #3. For example, pump long enough and both problems will resolve. We'll assume first that there is a real leak.

It's interesting to have a large chamber with portholes and fittings and o-rings and welds, and to know that somewhere there is something wrong that could be invisible to the naked eye. How will we go about it? The first step is to check obvious things. Bolts on any portholes should be properly tightened so the o-rings between them and the chamber are not distorted. The action of the mechanical pump - which will become the backing pump - should be checked by seeing if the pumping time to crossover (from mechanical pump to high vacuum pump) is typical. Seals that open and close, such as the bottom of a bell jar, should be checked for the proper amount of vacuum grease, if appropriate. O-rings should not be twisted. If all of those things are okay, we bring out the big gun - a leak detector.

A leak detector is a self-contained device that contains a vacuum pump and a simple mass spectrometer tuned to helium. The pump is connected to a fitting so it can sample gas that has been pumped from the chamber, which is then sent to the mass spectrometer. If any helium is detected in that gas, an alarm sounds.

Once the leak detector is connected and the chamber is pumped, we take a wand and spray helium on the outside of the chamber. Helium is an ideal gas to use because its molecules are very small and will slip through any openings big enough to be considered a leak; and because it won't blow up like the Hindenburg if something goes haywire. If we spray helium where the leak is, it will enter the chamber and then the leak detector, which will alarm and let us know we've found the leak.

One problem is that if too much helium is sprayed, the leak detector could continue to wail for a long while while we aren't really sure when the helium got into the chamber. (I really wanted to write "while while".) So filling the room with helium wouldn't work, although it would be a lot of fun talking.

I guess I have to aside this. If you inhale helium and then talk, your voice will sound like Daisy Duck's. Try it with a big helium balloon sometime. There isn't any danger because helium is non-toxic. If your lungs are full of helium, though, you aren't getting any oxygen, so don't get so carried away with duck talk that you don't take a real breath now and then.

Finding a leak with a leak detector requires releasing a very small amount of helium at the exact location of the leak, which is where the art comes in. I once worked for a company that manufactured custom vacuum equipment, and I had to find a tiny leak in a chamber that was the size of a Hummer. MMMMMMMMM, that was a lot of fun!

State of the project - clarification.

Sorry, I somehow overlooked that "oops" could be taken different ways. FM1 is missing because it was completed. FM2 should be completed on Friday. My own part in all of that ended last week when we were going to only one optic so I could devote myself to packing and, perhaps, sleeping in a bit.

State of the project - FM1.

oops

Vacuum doesn't suck, Part 2.

At atmospheric pressure (like you're in now!), any old fan can pump air out of a chamber. All the air molecules are pressing against each other and trying to expand. The fan blade hits them and pushes them away. But after a while there isn't as much air and the fan struggles. Air is pushing back against the blade, and a lot of those molecules get through.

When air molecules are bumping against each other and pressing in all directions, the pumped stream is called viscous flow. When the air molecules are hitting the walls of the chamber more than they're hitting each other, it's called molecular flow, and a simple fan won't do. What will pump the remaining molecules? Why, yes! Boiling oil!

There are many kinds of vacuum pumps, but one of the most common is called a diffusion pump. They are cylinders with silicone-based oil inside that is boiled by a heating element. They look like this:

The rising oil vapor goes into a device that directs the flow of the vapor back downward.

How does it work? Well, the remaining air molecules in the chamber are zooming around like crazed banshees on speed. Some of them go downward by chance, some hit a wall or another molecule and lose energy, and all of them have to deal with gravity. If they get low enough, the downward-flowing oil vapor pushes them down further. The more-concentrated air at the bottom of the pump is then removed by a simpler pump.

Here is the basic procedure which is used on a lot of vacuum equipment. There is a pump outside the production area (for cleanliness) that is similar to a fan, but the blades spin through oil to reduce leakage. Most of the time that pump, called a mechanical pump, is used to remove whatever molecules are loose in the diffusion pump. When it's time to pump down a chamber, a valve redirects the mechanical pump's action from the diffusion pump to the chamber - if the diffusion pump were exposed to atmospheric pressure, it would be overwhelmed. When the air pressure in the chamber reaches approximately 6% of atmospheric pressure, the mechanical pump switches back to pumping on the diffusion pump, and a large valve opens that exposes the diffusion pump to the chamber, and pumping the molecular flow of air begins.

Just a brief word about measuring vacuum. Atmospheric pressure is about 14.7 pounds per square inch, which is simply the weight of the air on that square inch. On half of a square inch, the weight would be about 7.4 pounds. That's not really handy, since it's area-dependent. So systems are used that measure the weight of the gases independent of area. Imagine that you have a U-shaped tube that has all the air removed and is partially filled with a liquid - mercury, for example. The height of the mercury in each half of the tube would be the same. But if you then opened the top of only one of the tubes, air would press down on the mercury in that side and the other side would rise. The amount that side rises represents the pressure of the air on the other side. It doesn't matter how big the two sides are, as long as they're equal.

Using that method of measurement, standard atmospheric pressure is about 29.92 inches of mercury. Using our U-tube, the airless side of the tube would see the mercury rise that high. That's equivalent to 760 millimeters of mercury (why is this country too dumb to switch to the metric system?). When measuring vacuum, 1 millimeter of mercury is called 1 torr, because "torr" is a lot easier to say than "millimeter of mercury".

If you're still reading, here is the last thing. When we started pumping our chamber, the pressure inside was 760 torr. To reach high vacuum, the pressure has to be reduced to 1/1,000,000 of a torr, and that's kind of low high vacuum. A billionth of a torr is common pressure for many processes.

Okay, only one more of these to go, since time is running out. The last part will be about finding leaks in vacuum equipment, which is probably the most fun part. It was for me, for sure.

Out and about.

When Twila was here in NY she was out exploring several days a week. My own explorations have been somewhat less frequent. If you leave out looking for latte shops, today was the first. I wanted to get my car some highway miles, I had to leave XM radio on for 15 consecutive minutes so it would start working, and I needed something to blog about. So I tacked a map on the wall, closed my eyes, and threw a knife at the map. Ten minutes later I was on my way to Armonk, New York.

One nice part of the trip was that I was in Connecticut awhile. It's always fun to pop into another state, even a U.S. state. There weren't any signs to let me know I was in Connecticut, but I could feel it. I felt... well, insured.

A short while later I was in Armonk. I'd hoped for a sleepy, picturesque village, but Armonk did not fit that bill. I did not, actually, see anything at all to recommend it. There was quite a bit of traffic, including some guy who leaned on his horn behind me even though there were three cars stopped in front of me and no place to go. No place to go also sums up Armonk, IMO, but all those cars must have been going someplace. Maybe they were just trying to get out of town.

My XM radio didn't start working, either. Now I have to find another reason to drive for 15 minutes. I wonder how long it takes to get to Costco.