Jeff N.

My experiance has been that a) you should store them in an oil bath and b) if they are not firm when pressed they are likely not servicable and should be replaced.

I purchased used ones on Ebay and they have been fine. I see lots of warnings about only using new ones but haven't had any issues so far.

Tom M'Guinn

Well, just a quick update. I used this vacuum idea on old lifters that had been sitting on the shelf in oily baggies for years (maybe 7-8 years). After sucking out the air, I only used lifters with solid --no give-- buttons. It worked really well -- zero clatter on start up, not even a tick. I'll be doing this whenever the cam tower comes off now...

Laust Pedersen

Great idea, why didn’t I think of that? I even have a vacuum station for occasional bubble removal when using epoxy and doing silicone castings.

The theory is quite simple. Vacuum grows the air bubbles, which then escapes the lifter (less pressure more volume, PV=nRT) and when the pressure once again is increased to ambient the lifter can only suck in the liquid it is submerged in.

From my casting experience a vacuum of at least 29inHg is needed to remove the vast majority of the air. So the typical 2 to 5inHg vacuum cleaner will not do much.

Laust

URG8RB8

I don't think you need anywhere near that level of vacuum, if they are achieving good results with a mechanical hand pump. Inches of mercury is a lousy unit for vacuum measurement. Torr or microns is much better and industry standard. 760 Torr is 1 ATM and 0 Torr is a theoretical black hole and impossible to achieve on Earth. Some of our chambers can reach a close approximate at 5.0 X 10-12 Torr, this will take months of pumping to achieve. I am not sure what the vapor pressure of the oil is, but I would assume it will start to boil around 50-75 Torr, which would make a huge mess. I would say 99% of the air is going to be removed at around 400-500 torr which is very little applied vacuum. I think you would be lucky to hit 650 Torr with a MightyVac hand pump, but I have never measured it with an accurate electronic vacuum gauge such as a Pirani or convectron gauge. Anything below 1.0X10-4 Torr will require a hot ionization gauge or a cold cathode (less accurate).

Tom M'Guinn

Air bubbles start coming out after the first squeeze of the MityVac hand pump. My Torr meter is out for repair, but I'd estimate the vacuum necessary at approximately that needed to suck a thick Jamba Juice smoothie through a standard drinking straw.

URG8RB8

Like your analogy better Tom! Yes that is about the gist of it.

aglaes

It doesn't matter what unit of measure you use - vacuum is vacuum. When you consider that a perfect vacuum is really only about -15 psig (ie 0 psi absolute), it's really not that much of a pressure differential. Theoretically, each time you cut the pressure in half (assuming the temp is constant) you will remove about half the air - ie the air volume doubles and half of it bubbles out.

ehall

Well, I really glad this worked Tom, but we won't be entertaining any whining and bitching when your pickles taste like crap, or won't stay hard. It's your fault there, Dr. Frankenstein!
Good idea!

URG8RB8

I will agree somewhat, but units make a big difference especially when dealing with absolute and people who really don't understand vacuum. Actually, 760 Torr which is 1 ATM is 29.9213 InHg, most gauges have it backwards and most people write it backwards. I have designed, fabricated, installed, serviced, and sold ultra high vacuum systems for over 20 years. I know a few things about UHV. As you stated the pressure difference in the normal world in psi appears to be very small, but the amount of technology needed to go from 1.0 X 10-6 Torr to 5.0 X 10-12 Torr is Huge, along with the cost! At this range there are literally only a few atoms left bouncing around in the chamber.

ehall

I just want to say, I think bacon tastes good, because I got nuthin.

URG8RB8

I am going to go off topic a bit, because I am stuck in traffic (everyday affair in Bangkok) and maybe a few people might find this interesting. I am going to post some pictures below of ultra high vacuum equipment in which most people never get to see. The technology is quite fascinating actually and most chip components today are made with this equipment including nearly everything in a phone and your computer. The first picture is an Edwards dry mechanical pump. It is capable of evacuating air (mostly nitrogen) at 80 cubic meters per hour or 47 CFM, but will max out at approximately 2.0 X 10-3 Torr depending on the condition of the pump.



The Edward's pump is used as a backing pump for a turbo molecular pump which is magnetically levitated and operates at 500 or 600 Hz. Yes Hertz, which is 30,000 or 36,000 rpm's. The picture below is a proper made in Germany mag lev 2000 which can evacuate 2,000 liters/second! The pumps go for around $75,000.00 each.





Here is another view:





One went bad today and I replaced it with a cheaper Japanese knock off, but it gave me a good opportunity to take a pic of the blades which spin so fast. Think jet engine in reverse. These are billet titanium. This pump goes for around $25,000 so still not cheap.





Another view of whole pump:





Either of these pumps will get a good clean SS chamber down to around the low seven scale say 2.0 X 10-7 Torr. In order to get most decent size chambers say 6 cubic feet to the eight scale or lower you must incorporate a cryogenic pump. The one below is a CTI 8F. This operates at 10 Kelvin and freezes most gas molecules, and then traps them inside of charcoal arrays.









It is powered by a large compressor similar to your A/C but uses ultra pure 99.999% helium and an operating pressure of 250 psi.





The compressor is above and a typical ion mill chamber is shown below. This piece of equipment accelerates argon ions at near the speed of light striking a substrate typically a semiconductive wafer. This will etch or erode the material at a very slow and precise rate. You can literally remove one atomic layer at a time.





The operating base pressure of this chamber is low eight scale and seldom if ever hits the nine range. There are too many O-rings. To get consistent nine or lower all metal seals must be used and prices sky rocket. To get lower than ten scale you need heavy duty titanium sublimation pumps which are extremely rare and expensive. OK back to the topic. Hopefully some people at least find this stuff interesting and I didn't bore anyone.

Voith

So will the vac cleaner do the job or do I have to get that erotic shop device to get one of those hand pumps?


Urg: impressive machinery..

URG8RB8

MightyVac hand pump will work just fine. See Tom's post above.

Dutch944

Nice info!

ehall

Pretty cool gear, but it ain't no pickle jar! That's for sure! Pickle jar tech FTW!

Seriously that is pretty cool. Thanks for sharing that.