I bought a 6cfm when i looked around. The 10 would be better for commercial jobs. The bigger pumps will freeze some of the moisture in the system. Hope that helps

 

Not likely... Do you use your refrigerant manifold to evacuate?

 

Rule of thumb is the cfm squared is how many tons of refrigeration it can do. So, residential 3cfm is ok...

a 6 cfm is good for 36 tons.

More importantly is your hose size and if your pulling through a schrader valve. A 1/4 hose will yield about .8 CFM. Thats right 8 TENTHS of a CFM! Do a couple searches here on proper evacuation techniques and micron gauges..

I use a JB Platinum 7cfm. I highly recommend JB vacuum pumps. You get what you pay for.

 

I find that the fewer CFM's the vacuum pump capacity - the less it weighs to carry - and the less space it take up in the truck. So far the smallest one I've found is 1.5 CFM. If there is any length of pull-down time difference between it and my 6 CFM pumps - it must be too little to get my attention.

I have a feeling that the CFM Rating is measured with the pump pumping free air. That is not what this industry ever requires. What we really need to know is the 'below 3000 microns' pumping efficiency Rating. <g>

PHM
------

 

ISo far the smallest one I've found is 1.5 CFM.

Refco has a 1.35 cfm eight pounder they say will pull to 15 microns I've been eye'n
No drain plug
You tip it over to drain
I have practice at that already lol



Does yellow jacket still make a 1.5?

 

iIuse a 4 cfm, and only do 4 ton's and less. Works good for me, by the time i finish installing line set insulation, sensing bulb, and drain, plus wiring i'm at about 350 micron's.

 

I have a 1.5 cfm belt driven cast iron ancient pump at the shop that I use for all sorts of stuff. Its never been any slower than my other pumps. Its weighs 56 pounds without the cart I carry it on so it doesn't see much field work though.

 

This sounds just like the monster I junked last year. You gotta be a man to lug that thing around, I used mine for everything for a while until I could get the funds to buy a real (read light weight) pump. I had installed wheels on mine so the biggest problem was loading and unloading. Sure glad that thing is gone.

 

If you are pulling through your manifold the smallest pump you can find will work just fine. If pulling through 1/2" hoses with the schraders removed and work on commercial units a 7 cfm will be nice . That is what I use and it is sucking down so fast I can hear the air rushing through the line set when it is switched on just as if I was pressurizing it with nitrogen

 

I use my Vacmaster 3 cfm. I also have a JB Platinum 5 cfm, but I think the Vacmaster is better. Both work great, though. I am never in any rush when pulling a vac. I will try to get the leak repaired or the line sweated back in first and get the pump running while I finish up the what is left.

On new installs, if possible, I find that leaving the system on nitrogen over night helps speed the process greatly. New clean oil helps a lot too.

With my JB, I seem to need to break with nitrogen more often than the Vacmaster.

 

I have a 3 cfm small cheapo rotary vane 2 stage from ebay that works as well as my yellow jacket bullet 6 cfm. I use 1/2 hoses and a yellow jacket evac manifold with a vg64 micron gauge. I have evacuated 5 ton units with long line sets just fine with the little one. It pulls low microns as long as the oil is clean.

 

I really like this article.
9. If I use a larger CFM pump, will I be able to pull a vacuum on a system faster?
In most cases NO. Using a vacuum pump on air conditioning systems from 1 ton to 10 tons, you will not see the difference between a 3 CFM pump and a 10 CFM pump. For example, if you put a pump on a system and you notice within 2 minutes the pump quiets down and you cannot really feel any air leaving the exhaust. This means that there is no more CFM left in the system and you are now working with molecules. Thus, at this point if you replaced a 3 CFM pump with a 10 CFM pump, there is no change in vacuum or time.


http://www.jbind.com/technical/faq-pumps.aspx







1. My vacuum pump runs, but I cannot get a vacuum.
The coupler between the shaft of the pump and the shaft of the motor is either broken or slipping. Make sure the set screws are tight on the flats of the two shafts.
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2. Why is it so important to change the oil often in my vacuum pump?
The proper oil in a vacuum pump acts as a blotter and absorbs all of the moisture and non-condensables. As the oil becomes saturated with these contaminants, the efficiency of the pump is dramatically reduced. Maintaining clean oil in the pump ensures that the pump will operate at peak efficiency and prolong its life.
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3. Can I use any oil in my vacuum pump?
No. JB Black Gold oil is extremely pure and non-detergent. Black Gold is hydro processed which means it goes through a series of catalytic steps rendering the oil extremely refined, more viscous, and more stable. The result is a clear mineral oil that will alert you to contamination sooner as it becomes cloudy or milky.
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4. Why is it important to change my oil when the pump is hot?
As the pump cools, the moisture and contaminates start to separate in the pump and when drained, the contaminants cling to the walls of the pump. When you refill the pump with new oil, those contaminants will mix in with the new oil as the pump warms up resulting in the new oil quickly becoming contaminated.
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5. If I am always pulling a vacuum on clean, dry systems, is there a way to check my oil in the pump to see if it is contaminated and not have to change it so frequently?
It is recommended that a micron gauge be attached directly to the pump and should pull to 50 microns or lower if the oil is clean. If the micron gauge does not pull to 50 microns, it is an indication that the oil is becoming contaminnated and should be changed.
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6. Other than pulling air out of the system, how does my vacuum pump get rid of the moisture in the system?
Most two stage vacuum pumps will go low enough in vacuum and reduce the atmospheric pressure within the system, thus allowing boiling of the moisture at a lower temperature. Once the moisture is in a vapor form, it is readily removed by the pump.
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7. What is a gas ballast and how do I use it?
On the initial pull of vacuum on a system, the gas ballast is open allowing the initial volume of air in the system to bypass the oil so as to not contaminate the oil immediately. When the pump starts to quiet down, close the gas ballast and the pump will start reducing atmospheric pressure in the system to boil the moisture and non-condensables.
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8. What is a blank-off valve?
The blank-off valve acts no different than a water valve. Open it, and with the pump running you will get your desired vacuum. Close it, and with the pump running there is no vacuum.
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9. If I use a larger CFM pump, will I be able to pull a vacuum on a system faster?
In most cases NO. Using a vacuum pump on air conditioning systems from 1 ton to 10 tons, you will not see the difference between a 3 CFM pump and a 10 CFM pump. For example, if you put a pump on a system and you notice within 2 minutes the pump quiets down and you cannot really feel any air leaving the exhaust. This means that there is no more CFM left in the system and you are now working with molecules. Thus, at this point if you replaced a 3 CFM pump with a 10 CFM pump, there is no change in vacuum or time.
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10. What is a micron?
There are 25,400 microns in an inch. Therefore, with a compound gauge reading 0 inches to 30 inches, there are 762,000 microns.
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11. I have been using my low side gauge to pull a vacuum, is this wrong?
YES. The low side gauge knows only atmospheric pressure and cannot sense moisture or non-condensables. A micron gauge is a heat sensing device that not only reads atmospheric pressure, but also measures the gases created by the vacuum pump as it boils the moisture. For example, if you were to pull a vacuum on an enclosed bottle of water, the low side gauge when pulling a vacuum will read a perfect vacuum. Using a micron gauge, it will immediately tell you with a high reading the you have a problem in you system.
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12. I have been pulling a vacuum on my system using a micron gauge and cannot get it down to a low reading.
See FAQ #1. Another possibility is that some oil may have entered the micron gauge and is giving false readings. The remedy is to pour regular rubbing alcohol into the connector on the micron gauge, shake, and pour out (do not use a q-tip, rag, or any other material - use the liquid alcohol only). Do this about three times, then try to pull a vacuum with the gauge.
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13. I am able to pull a vacuum on my system, but when I blank-off, the micron gauge rises rapidly.
Unless you are using JB`s DV-29, copper tubing, or flexible metal hoses, it is not recommended to use your existing manifold and hoses for blanking-off a system to check for leaks. Hoses work very well under high pressure. Vacuum is very critical in leaks, more so than pressure. All charging hoses, including the black hoses 1/4" or 3/8" permeate. Where the crimp is on the brass to the hose also has possible leak issues, and the gasket at the coupler is a major leak offender. The vacuum industry uses O-rings on most couplers. When you screw down on a gasket, it goes into many contortions and will not seal. When using an O-ring, you screw down on it to get a metal to metal seat and the O-ring lies around the lip of the flare giving it a positive seal.
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14. Can I mount my micron gauge onto the vacuum pump?
It is not recommended to do so as you are reading what the pump is doing and not what the pump is doing to the system (see DV-29). It is suggested that you tee off on the suction side of the system and mount the gauge there.
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15. How low of a vacuum should we pull on a system?
JB recommends that a system be pulled to at least 250 microns and held at least five minutes. On any polyester oils in a system, it is recommended to pull a much lower vacuum as moisture is very difficult to remove even with heat and vacuum.
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16. Why does the micron gauge slowly fall back and then start to hold after pulling a vacuum and blanking-off?
The reason for this is there is equalization within the system. If you pull a vacuum lower, it will then fall back at a shorter range and hold.
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17. Why do I need to check the oil level when the pump is running?
The reason for this is that if the vacuum is not broken before pumps are shut down the oil in the cover will seek the vacuum still in the cartridge and intake chamber. Then the oil level will drop in the sight glass and give the appearance of a low oil level. Then if the pump is refilled to the oil level line and the pump started, the oil that got sucked back into the cartridge and intake chamber will be kicked back into the cover and now you’ll be over filled and the oil will shoot out the handle (exhaust port).

 

my wife tells me that size matters...i have no idea why she would know anything about vacuum pumps though.

 

hmmmm . . . . maybe you should look into some new ways to maximize her utility value?

PHM
------

 

I have 3 different vacuum pumps, a JB 3 cfm, JB platinum 7 CFM, apion TEZ 8 CFM. I did some testing on pulling a vacuum on a 50lb recovery tank and my results made me rethink my purchases on vacuum pumps a little. I pulled with all three vacuum pumps a 1/4 hose and 3/8 hose hooked directly from the vacuum pump to the tank, vacuum gauge reading off the other side of the tank. My 3 cfm pump pulled a vacuum to 500 micron faster than my 8 cfm did with a 1/4 hose. The moral of the story is no matter how big the vacuum pump is it doesn't matter if your using anything less than 3/8 hoses. My current set up is a yellow jacket 4 port gauges, I removed the high side and low side gauge flare fittings and installed 3/8 fittings. I replaced the 3/8 vacuum fitting with a 1/2 fitting and use 1/2 hose off my vacuum and 3/8 hoses everywhere else. This is probably unnecessary for anything residential as I work on systems that hold between 25-100 lbs refrigerant. For a residential guy the biggest purchase you can make is good 4 port gauges with 3/8 hoses so you have a vacuum port to isolate. And don't forget the heavy duty charging hoses and core removal tools. That and a good quality vacuum gauge will be a better investment than the high cfm vacuum pumps any day.

I actually somewhat regret spending the money on the high dollar 8 cfm appion because my 7 cfm pulls a vacuum just as quick on systems holding 100 lbs. With my appion I have to change the oil 3-4 times during a vacuum vs the JB I change 1 time either before or after. This allows me to leave it alone and take longer lunches : )

 

I was happy with my 10 cfm JB. I like my TEZ a lot. I use (most times), 1/2 inch hoses with 3/8 and 1/4 ends. Still when its -8* out it seems to take forever to get to 500 microns.

 

Sounds like you have some nice pieces. Why not get rid of the manifold and extra hoses and connect the hose(s) direct to the pump?

 

Do another test with just one ½" and one ⅜" hose to your recovery tank direct to your pump no manifold. Big difference loosing the manifold and total hose length.

 

I've had my eye on the Refco RL-2 but the cost of the others are tempting

http://www.refco.ch/us/products/vacuum-pums.php

 

RL-2??? Seems quite compreable to the value.... is the RL-2 the one you were thinking?

Is refco good do you know?

 

Yes you're not wrong about the Value pump being expensive to import. They won't ship out of Europe and it's 95€ to get it to Austria where I can get my mail forwarder to send it on to me. There looks like there's a slightly larger variation of that pump on aliexpress which might be more achievable to get cost effectively.

 

Im waiting for this awesome guy...

http://toolguyd.com/makita-cordless-vacuum-pump/

 

Yeah I got excited at first until I saw it was only a single stage pump. I'm trying to get my brother in law who only works on auto ac to get one first.

 

It like three times the money

 

The smiley face has got to be worth something...

Any idea on the quality of refco?

 

It Swiss made
Can't be too bad right

There is a rep here. I guess the next size up may be more bang for the buck.

 

It Swiss made
Can't be too bad right

One step up would defeat the whole purpose of this exercise... lol

I found the RL-2 for under $300

 

I could have made a tree and connected directly off the pump. The systems I work on have pump down solenoids and eev's and I like being able to shut off the pump and have both sides of the system open to each other while checking if the vacuum holds with the pump off. Otherwise I could have the vacuum on one side of the system and not know if the other side is rising. I will usually be able to get the two hoses off the guages hooked up and an additional hose directly off the vacuum pump with an appion core removal tool to isolate it.

 

If you buy some solenoid magnets and put one on each solenoid valve - in place of the electro-magnet coil - you will have the entire system open all at the same time.

PHM
---------

 

Hey,

The RL-2 is rock solid, and yes it pulls down to 15 microns. Even with the smiley face.

However, I would get the RL-4. It has 3/8" and 1/4" connections and yes.... a drain plug.
Nearly as small as the RL-2 but better performance and its only 2.3 CFM

I would and do put these small pumps against large CFM 9-12 pumps and pull a lower vacuum every time.
I mean with a digital vac gauge connected with a short hose as a test.

Iceman, shoot me a line and I will send you one out for free.
ahhhh ......as a "extended" field test.

 

The CFM rating in terms of vacuum pumps is very misleading. As is the sizing of hoses, and direct piping with copper and all the other things you will see / hear preached about. It more about bragging rights than it is about worthwhile performance gains.

You will be far better off improving yourself, your work habits, and your working efficiency than in buying any bigger vacuum pump.

Think about what You are doing as a Work Performance. Every thought, every movement, every step. Sort the required steps and then arrange them in the most efficient order. And then do them in that order. For single example: Always do all the piping first. Then leak check. Then evacuate. While the pump is running - start on the other job-tasks. Wiring, insulating, etc.

Also: Never walk back to the truck empty-handed. Anything which can be put away / you are done with it - take it back When you are going back anyway to get the next thing out.

I have pumps to 10 CFM and I've rented them to do hundreds of CFM. They all sit on the shelf now. About 99% of the time I use a 1.5 CFM vacuum pump. <g>

The CFM "rating" is with the pumping in open air. Something which you will never be doing. The entire internal volume of the systems you will be working on are a few cubic feet. In the first minute of pumping it's pretty much empty. What counts is how Low the pump pumps - not the volume it will pump at atmospheric pressure.

A vacuum pump pumping in a vacuum has almost no capacity. It's no different than a refrigeration compressor. No suction pressure and the capacity plummets.

Start with You -

Arrange your work habits into a smooth, efficient, and streamlined fashion and you will save far more time than you would by having a larger vacuum pump. If you get to the point where you work on larger systems - buy more smaller pumps. You gain both versatility and redundancy. If your single big pump breaks you are dead in the water. And small pumps are easier to carry. <g>

BTW: Do all the piping First.

PHM
---------

 

PHM If a system holds 1 ft³ of air at ATM
It still will have 1 ft³ of air at say 1000 microns and your pump of a good one will still be moving a similar CFM as free air only you are moving less molecules of air per ft³ as long as your connections don't restrict the pump.
The pump performance does drop off the deeper you pull but it happens lower than you might think.

 

Expat, can you send me an email, I'd like to speak with you but cannot find your private message or email. Thanks

 

Poodle Head,

You are more correct than you even know.
It is soooo refreshing to hear (read) another human being say what I have been preaching all over the world.

The first question from a field service engineer looking to buy a new vacuum pump should be, "what is the factory micron rating?"
That is a measure of how hard a particular pump can PULL at optimum conditions, which are new pump with fresh oil connected to an accurate digital vacuum gauge with a short copper tube with braised 1/4" flare nut connections. If you use a flexible hose a good vacuum pump will pull air right thru the walls of the evacuation hose and the micron gauge will read it.

Remember on a typical install lets say 10 tons or less, all the "air" is gone after 30 min or less.
At that point does more CFM help you? NO!

At that point what you are evacuating is moisture molecules. A.K.A. water.
So, what matters is how fast can a pump PULL the moisture out of a system.

I often use an automotive analogy. CFM is equal to horse power and Micron rating is equal to Torque.
You all know the difference in-between HP and torque.

What do you need to pull the water out of a system?
Lots of torque... and fresh oil.

CFM only comes into the equation on large commercial systems, where you are actually better off using multiple high torque pumps on the high side and low side of the system. Remember whichever side you install a single pump on you will have a closed metering device restricting your flow from the other side of the system low to hi or hi to low depending on where you hook up you single pump. So on large systems use two pumps and PULL from both sides of the restrictive metering device.

For some reason the manufactures marketing has bamboozled the public into believing higher CFM is better or even worse the HP of the motor running the pump.... CFM is less than half of the important part...
But men being men generally believe more is better so they want a high CFM pump regardless of its micron rating.....
Its a false assumption but you just try to change that worldwide marketing trend.... Impossible.
Aaaaanyways.....

The key to a fast and deep system evacuation is a vacuum pump with low micron rating, fresh oil, oversize evac hoses and a CRT. (core removal tool) that has a blank off valve and a upstream port to connect an accurate digital vacuum gauge.

 

...CFM only comes into the equation on large commercial systems, where you are actually better off using multiple high torque pumps on the high side and low side of the system....

so, how many "high torque, 1.5 CFM" vacuum pumps should I use on my 3,000 ton chillers?

Answer: 0

CFM does make a difference. Sure, the ability of a vacuum pump to achieve a low micron rating is ultimately important and just about any brand any can achieve <100 microns right off the pump, however, to claim CFM only makes a difference in a generic term such as "large commercial" is misleading. CFM does make a difference.

The smaller and cleaner/newer the system is, the less difference CFM size makes, however, on the same size system, with the same connections, a larger CFM pump will be drawing a deeper vacuum per revolution and will get your evacuation done faster.

How much faster? That depends on your system size. But CFM does matter.

 

Jayguy,

In your example you are correct.
Even if it is an extreme example.

Of course you would never use a 1.3 CFM pump on a 3,000 chiller system. That's just stupid. Not even two or three of them.
However, if you used say two 5.3 CFM pumps instead of one 12 CFM pump that is a more efficient way to do the evacuation.
Or two 10 CFM pumps with a good micron rating would be even better.

My comments were exclusive to systems under 10 tons.
Lets keep it real.

 

...My comments were exclusive to systems under 10 tons.
Lets keep it real.

and my example was made up?

your EXAMPLE was 10 tons or less...not your comments.

This is what pisses me off.

guys come on here claiming everything under the sun (some are correct and some are not so correct) and don't realize their impact. As I have just shown (and you agreed with me), the "devil is in the details". We are an industry of specifics and yet many talk in generalities. Many residential guys read and learn a lot here. For many of them, your statements are applicable and correct regarding vacuum pump size. The problem becomes, that since you didn't clarify your conditions (10 ton system), those same residential guys take it as an absolute fact. Then some of them move to a commercial company where they work on larger units...taking your "facts" as gospel...when they shouldn't.

if you (meaning everybody) only want to talk about 10 ton systems and under (or over, or whatever), then great! Have at it! But make sure you clarify what you are talking about.

 

Nice iceman.

Having all the torque with no traction is good for doing burnouts but not for speed.
Nice addition to the automotive analogy.

Larger hoses, give your torque pump the traction it needs to keep pulling.
I'm going to steal that....