Vacuum Pump Discussion

My gauge is an average vacuum gauge that reads from
0 to -30"hg. Similiar to this
http://www.drillspot.com/products/72713/Generic_5WZ37_Vacuum_Gauge

Hey slimjoint, How long have you had the pump? do you change the oil regularly? do you have the correct threaded barb attachment for your pumps port? are all barb to hose connections fitted with hose clamps tightly to ensure seal? Are your threads sealed? Whats your pumps micron rating?

walt cunningham said:

i would re-check your gauges hamma. a 2 cfm pump should not be able to go above 27hg.
i was told i needed a 6fm pump to reach 29.9
someone i know on here just got the cheap one like yours hamma and it only did 26 or something

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I can boil water at room temp. I don't need a gauge to tell me that i can get 29.5, but I do have have a gauge that goes to 30hg and I max it out every time. Use smaller chambers. My buddy has the red robinaire and he can pull 29.5 on a vac oven.
These are the temps with the hg to boil water it was a chart but didn't copy and paste so well.

unless you have a digital micron gauge, then you really cant draw valid conclusions about vacuums in the 25micron range. reading the bottom of a dial gauge just isnt valid for those vacuums. That said, I had a "cheap" $100 digital micron gauge from ebay, and it wouldnt go below 50 microns despite my pump being sold as 25 micron capable. I bought a better gauge, provac for about $200, and it shows that it can go to 22 microns.

if you have any leaks in your system, even seeminly inconsequential leaks, you might not get to your maximum vacuum. to test, you put just the gauge straight to the pump, and any rubber seals should be wetted with mineral oil.

and if there is any moisture or butane left, the residual pressure may just be incomplete purge, not a failure of the vacuum, it cant reach maximum vacuum while there are still volatiles in the system.

but we need a pump that can pull deep deep vacuum to remove residual solvent quickly

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at low pressures, the small difference in 30 or even 100 microns vacuum difference isnt going to be the limiting factor in the speed of purge. the temperature of the oil, the surface area, and the depth of the puddle of oil are much more limiting factors. and unless you have a very large volume system, the cfm isnt important here. the cfm in vacuum pumps becomes important when vacuuming out large volume refrigerant systems.

So what pump works then? Did we get an answer to what pump works? I am tagged on this thread.

Probably a bit pricy, but I use these for work

http://www.knf.com/usa.htm

OrganicBuds said:

So what pump works then? Did we get an answer to what pump works? I am tagged on this thread.

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any working hvac vacuum pump works fine, and an havc vacuum pump probably works better than a recovery pump, but you can use a recovery pump. the difference in cfm and small differences in the final possible vacuum can't possibly make a difference in removing butane from a viscous solution. sure, you can come up with theoretical small differences, but they are moot in practice.

edited to remove grandiose stoned talk ---

What FOAF said. There are 760,000 microns to one atmosphere and we have conviently broken that down to reading 29.92hg on an analog gauge scale of 0 to 30 hg.

At sea level there are of course only about 29.92 hg, so every mark on that analog scale is 25,401 microns.

As long as something is boiling off, the pump can't reach full vacuum. One of the ways that I can tell how much is boiling off, is by how low the pumps can pull down the chamber.

My analog gauge has a calibration screw and I had to reset it every time I used it for months, but as it finally wore in, it stayed close to calibration. Never the less, I still have to recalibrate it regularly. When it was new, it would fail to return to zero by up to three graduations.

It has been unecessary to measure in microns, for anything I've tried, because 29.5"hg is low enough.

For measuring at a micron level, something more precise than an analog gauge is required. I started measuring in microns, but continued to use my analog gauge after my digital micron gauge failed, and haven't had any issues. The effects aren't that refined or subtle.

I have picked up a Hastings vacuum gauge and am searching for a DV-6 sensor tube for it. It is a logrythmic analog gauge, that measures from atmosphere to 1 micron, and has set points with contacts.

Organicbuds - I would suggest anything american made. Yellow jacket bullet series and JB industries Platinum series or eliminator series are all great quality american made vacuum pumps. I'd say the best out of all them would probably be the JB industries Platinum series, these are considered premium pumps and are rated down to 15 microns. Even if some of the cheap chinese brands work ok, lets support american made tools and not crap from overseas.

Foaf - Ya I know my average vacuum gauge is not going to give an accurate reading and that a digital micron gauge is necessary for a correct read out. But I can close my inline ball valve between my pump and chamber, shut the pump off at full vacuum and it does not loose any vacuum at all it stays right at -28"hg. Would'nt that be an indicator of no leaks in my system? I will attach my gauge rite to my pump to see it gives a different result, but I'm pretty sure I have no leaks. I also keep my oil at a constant temp(110f-130f) to keep it's viscosity lowered while at full vacuum, along with my oil being spread very thin on the parchment. Even doing all this it still takes me 3+ hours to purge a few grams. I can tell it's still removing solvent 3+ hours in by the rainbow tinted bubbles that continue to form. Would you consider that a normal purge time for that small of an amount? I feel like people are purging batches that size in a fraction of the time. Thanks for your replies

GW - Thanks for sharing your gauge experiences

Hamma - Thanks for graph/numbers you posted

More info the better

I don't suggest you shouldnt try to figure out ways to purge faster, but I bet you are mostly purging your oil more completely than some of the reported quicker purges. I really don't keep track of how long a minimum vacuum purges take, because I put mine on an interval timer so it cycles on for a few minutes and off for a while, and leave it overnight. My oil is usually not spread very thin either. It sounds like you are doing it just right to me.

Is the butane you are using pure? ANY non condesibles in the area under vacuum will cause it to not reach full potential.

I have a JB Eliminator pump. It's the bomb. High quality, high value for dollar, and excellent company to do business with.

Every time I had a issue with the harbor freight 2 stage pump it was my fault, I had vacuum leaks. Vacuum leaks can be very tiny and if your not using a vacuum grease to seal joints then thats your problem.

midwestHIGHS said:

everything has hose clamps where they're barbs and the correct 1/4" SAE threaded barb attachment. Threadings are all sealed.

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.

I had leaks with ground glass and real dow corning vacuum grease. Also fyi hose clamps the screw kind are far from round.

i have a robinair 15500 5cfm, don't change the oil as much as i should but she runs like a champ. has an internal check valve so when you turn it off, the vac is held, no external valve like on some other models. i personally like that, but others may not.
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here's some info i found from around the way -

From http://www.licensedelectrician.com/Store/Vacuum_Pumps.htm

The Importance of Deep Vacuum in refrigeration :


The purpose of a vacuum pump is to remove moisture and air from an A/C-R system. Modern systems are built tighter and charges are more critical. That means these systems have a greater sensitivity to moisture and other contaminants, making thorough evacuation more important than ever before.

Moisture in a refrigeration system, directly or indirectly, is the cause of most problems and complaints. First, moisture can cause freeze-up in a system. Moisture is picked up by the refrigerant and transported through the refrigerant line in a fine mist, with ice crystals forming at the point of expansion.


“Freeze-up” is not the only problem caused by moisture. It can also result in corrosion, the effects of which are not apparent until the real damage has occurred.



Moisture alone is bad enough, but combined with refrigerants containing chlorine, hydrochloric acids can form. These greatly increase the corrosion of metals.
Also, refrigerant oil rapidly absorbs moisture. Water-formed acids combine with the refrigerant, forming a closely bonded mixture of fine globules.


The effect is called sludging and it greatly reduces the lubricating ability of the oil.
A vacuum pump removes troublesome moisture by lowering the pressure within the system and vaporizing (or boiling off) the moisture, then exhausting it along with air.


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From http://www.hvacfun.com/a-how-to-pull-a-vacuum.htm

What vacuum pumps do

A vacuum pump doesn't actually vacuum out the system, but rather removes moisture by lowering the pressure within the system and reducing the boiling point of water at normal temperatures, thus vaporizing the moisture and air out of the system.


For vaporization to occur, you need to expose the system to 1.066 psia at a temperature of 104 F (the boiling point of water is 27.75 inches of vacuum at 104 F). The lower the internal pressure the lower the boiling point of the moisture. So the lower you bring the system, the less heat you need. Once all the moisture has been vaporized, both the pressure and the heat dissipation rate will decrease, and the measurement on the gauges will decrease.


The more liquid there is in a system the longer it will take to pull a vacuum. If a system has a leak, the vacuum will not be deep and the needle will rise when the valves are closed and the leak or the moisture in the system will not allow you to produce a deep vacuum.


There are two main types of vacuum pumps: single-stage and two-stage. Single-stage pumps are used when we do a triple evacuation style. The two-stage pumps are used when we need to pull a deep vacuum. Most two-stage vacuum pumps can pull down to about 50 to 80 microns.



No pump will remove all the air. If your pump can produce 28 inches Hg, it will remove only about 94 percent of the air. You will need to heat the moisture to about 100° F or higher, then the moisture can be pumped out as vapor.
Some service techs evacuate a system for eight hours at a high temperature or some will do it even longer at a lower temperature. Often the evacuation procedure needs to be repeated a few times to ensure that it is free of moisture, but only by the use of a micron meter can we determine the level of vacuum achieved.

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From http://www.totaline.com/pr/vacuum_pump_oil

Don’t Wait to Change that Vacuum Pump Oil

With the arrival of spring and warmer weather, now is the time when HVAC/R technicians will likely be servicing AC units. When you’re called upon to charge a unit with new refrigerant, you’ll use a vacuum pump to remove system contaminants first. But where do those contaminants go? Directly into the pump oil, said Totaline Category Manager Ken Rando.

“Vacuum pump oil is one of the most rigorously used oils, and it’s used in a tough environment,” Rando said. “Vacuum pumps are designed to remove moisture and air, as well as contaminants, from the system. The accumulation of contaminants in the vacuum pump oil is normal.” Because of this, Rando said that it’s important to change the vacuum pump oil after each and every use.

“The pump oil is like the life blood of the vacuum pump,” Rando added. “In addition to providing all the lubrication and sealing of the pumping components, it also collects all the moisture and contamination of the system.”

“Because the vacuum pump oil holds the contaminants in suspension, they float around in the vacuum pump system. If you don’t remove them, they can significantly shorten the life of your vacuum pump, which is why you should change the oil every time,” Rando said, adding that replacing a vacuum pump can be a hefty expense – a new one can cost between $300 and $400.

For best results, Rando recommended that the pump run for at least 15 minutes before changing the oil. “The reason for that is to get the moisture and contaminants floating around and suspended, rather than leave them laying at the bottom of the tank.” He also said that it is imperative to use good quality vacuum pump oil, and to buy in quarts or gallons.

Here's me goin' hard on the vac oven!

Maxed out!

Some skirt steak for fajitas, vacuum marinaded of course.

^Nice! I'll admit to using mine for that too... actually kept my old pressure pot just for food

back on topic, anyone have experience with the yellow jacket "bullet" it looks to me they're cheapest model:

http://www.amazon.com/Yellow-Jacket-93600-Bullet-Vacuum/dp/B003AJIWOY/ref=pd_sxp_f_pt

maybe thats over kill, i just want something better than my old HF 2 stage 3CFM, in which ive had two failures

i hear a lot about the robinair 15500, anymore long term, reports?

Thanks for the pictures hamma, total home run! Dank steak marinating with vacuum pumps. I don't know why I never though of that and I marinate almost daily! I've been looking at vacuum ovens to, found a couple under $1000, but some look really used and beat up. Where did your buddy get his? Also is the hose from the vacuum oven to the pump just shoved onto the samller 1/4" port with no barb attachment? If so thats a stellar seal for tubing shoved onto a male threaded port. I also noticed you have a thermometer in the oven, I've done that in my chamber, but the negative pressure pulls on the thermometer to, giving me a much lower reading than the actual tempurature.

Synthacide-If you are trying to save a little money, I'd either get one of the yellowjacket bullet seriers, its their cheaper pump seriers than the Superevac series or The JB industries Eliminator vacuum pump, it's their cheaper pump as well. Both of these pumps are two stage, rated down 25micron or better and quality made in America. Personally though why not just get the best and be done. Go with a yellowjacket superevac 2stage 11cfm or Jb industries 2stage 7cfm platnium series. Both are rated down to 15 microns or better, now thats a deep vacuum! hehehehe

Thenewguy2012- Thanks for the general info on pumps!

The hose's are shoved on then twisted, so they are kinda threaded on.I have found that when working with vacuum, if you use rubber or silicone for hose's, the pull of the vacuum will make good seals.
The thermometer is made for ovens, not vacuum, so maybe that has something to do with it. It is accurate, I have tested it with an laser thermometer.
My buddy got his used on ebay for a steal. You must be very careful buying a used though, no telling what has been through these things.

I second the advice given by "midwestHigh"...

hammalamma,
I am envious of that vacuum oven; they are certainly harder to find great deals on...
This may sound kind of weird, and off topic, but how much better is the marination under vacuum? My little brain is puffing smoke thinking of all of the things I could marinate for dinner... Any local places that sell those vacuum containers? I tried BBB with no luck.

Back to vacuum:

If money is really tight, the CPS model VP6D has worked great for me over the last two hundred plus hours; for around $200, I haven't seen many other two-stage 6cfm pumps which deliver on a 10micron vacuum rating.
If you believe my CPS Digital micron gauge, this pump with a fresh oil change just pulled a 9micron vacuum in under two minutes with the gauge attached directly to the pump's 1/4"flare fitting... While I am certainly surprised to see this pump pull that vacuum; it has been producing nothing but "Fire" since I started using it...

While I do have a JB Platinum on order for use with my newly finished Terpenator, in no way do I think of the CPS pump as inferior pump in terms of function; how long it lasts is certainly an unknown, and the replacement part is more expensive than the cost of a new pump. In the end, I decided to go with the JB for long term use with my Terpenator because I wanted the utmost reliability and performance. I am sure the Yellow Jacket pumps are great, I just happened to choose JB...