Is this a decent vacuum pump?

[plzdontbetaken]

Hi,

I am looking to purchase a proper set of tools to build a phase change cooling system. I am currently studying Mechanical Engineering in school... so I am on a budget, but I would like to buy nice enough equipment to put together a quality unit (more than one if I enjoy myself ).

The first unit I build will most likely be a chiller, but I am posting here because this section seems to get more traffic and it wouldn't really make a difference for my post content.

On that note, would this be a good purchase? If not, can someone point me towards something that would be a better fit? At this point, I do not have the real world experience to know what I should buy for myself, so any help is appreciated.

Thanks

[Stewie007]

That should be just fine. You could check ebay to see if anyone is selling one, though. If you buy one new at least you can take care of it from the start. However, there are some pretty good deals there from what I'm seeing.

http://www.ebay.com/sch/i.html?_from...All-Categories

[plzdontbetaken]

That should be just fine. You could check ebay to see if anyone is selling one, though. If you buy one new at least you can take care of it from the start. However, there are some pretty good deals there from what I'm seeing.

http://www.ebay.com/sch/i.html?_from...All-Categories

Thanks Stewie. I think I would be more comfortable with a new one than the used ones off of ebay unless I knew the person that was selling it to me or it was someone off of the forums.

[wdrzal]

Two Stage Performance Using Twin-Port Technology

In the first line of the link the way it is worded doesn't exactly say it's a two stage pump ?????? And doesn't give a micron reading either.
be careful !!!!

plzdontbetaken

[kitfit1]

Can i please offer a word of caution here. I also bought the 3.0 CFM pump linked to about a 18 months ago.
These pumps are manufactured in China (that's why they are so cheap). The one i bought burnt out within 30 mins of first running it, even with the correct type and amount of oil in it.
Because of the cost of shipping it back to the seller (Hong Kong ), it was cheaper to take the loss and buy a good quality branded pump (which i did).

My advice : don't touch it, get a good branded pump.

[DetroitAC]

^ I second that, I'd rather have a used good quality pump than a cheap Chinese pump.

Yellow Jacket/Ritchie, JB, Robinaire, Edwards

[plzdontbetaken]

In the first line of the link the way it is worded doesn't exactly say it's a two stage pump ?????? And doesn't give a micron reading either.
be careful !!!!

plzdontbetaken

Can i please offer a word of caution here. I also bought the 3.0 CFM pump linked to about a 18 months ago.
These pumps are manufactured in China (that's why they are so cheap). The one i bought burnt out within 30 mins of first running it, even with the correct type and amount of oil in it.
Because of the cost of shipping it back to the seller (Hong Kong ), it was cheaper to take the loss and buy a good quality branded pump (which i did).

My advice : don't touch it, get a good branded pump.

^ I second that, I'd rather have a used good quality pump than a cheap Chinese pump.

Yellow Jacket/Ritchie, JB, Robinaire, Edwards

Thanks for the words of caution.

I chose that one because of the price, but from others experience it is a poor choice, even for the price. Can anyone recommend me a good pump instead (that won't break the bank)? What would I be looking at spending for a new one? Does anyone know anyone looking to sell one used? (anywhere around Atlanta and I could avoid shipping) I am hesitant to buy a used piece of equipment from a non reputable seller because I have seen how some people take care of things.

[Stewie007]

You'll find that a Robinair, JB, etc will drop you probably around approximately 300 or more. There are some Robinair pumps (15601,15401) for around that price. I am quite sure you'll find plenty of selections from the other brands, I just didn't look that far. The one that you found is not a brand I recognized, and I do agree with the further comments that it appears to be a questionable product.

It reminds me of times when we switched to Chinese suppliers for things like oil pumps only to find that it was a monumental error. I don't know what was more humorous... The engineers frantically pacing back and fourth trying to figure out what to do, or the bean counters' refusal to believe that their cheap skate mentality lead to such a drastic cost cutting error. The problem with a lot of non-reputable China suppliers are the conditions of their factories and total lack of quality control. You never know, that vacuum pump could have been built in a messy garage; or more likely the internal parts were. I mean that quite literally; some of those places are just a mess.

[wdrzal]

Yellow Jacket/Ritchie, JB, Robinaire, Edwards

DetroitAC listed the best pumps,..........I have quit a few Robinair 15600 6CFM pumps.

Robinair sales pumps in their CoolTools line (model 15600 6 cfm & 15400 4cfm) that are real good pumps,look for models with the same style.but they also sell the chinese pumps rebranded as Robinair........so be careful.
The rebranded pumps look like the one in the orginal link you posted.


Look at this link: The blue pumps are the good ones. The red are chinese. Look at the style not only the color because the older robinair pumps are the same as the now blue ones. http://www.amazon.com/Robinair-15600.../dp/B000JFNAJE

[Stewie007]

^ +1 to Walt and DetroitAC

These guys know what they're talking about, so listen.

[Newb101]

Well darn. I was going to say go for the red Robinair, now I know why they are so cheap!

Btw, I was told there is such a thing as going too big. I remember something about 1cfm/ton (12,000 BTU) system size. "Boiling oil" or sucking it out. Supposedly. I don't know how you can boil out the oil. But I could see perhaps displacing it.

[Stewie007]

There is indeed such a thing as going too large. Over sizing the pump can cause an initial pull down that is too quick. This can cause moisture to freeze inside the system, where it will remain for the duration of the evacuation; not good. For these units, 3-4CFM will be fine. I can't imagine him buying a pump that is too big considering his budget.

[LMB]

There is indeed such a thing as going too large. Over sizing the pump can cause an initial pull down that is too quick. This can cause moisture to freeze inside the system, where it will remain for the duration of the evacuation; not good. For these units, 3-4CFM will be fine. I can't imagine him buying a pump that is too big considering his budget.

Interesting ...... I did not know that . Good info to keep in mind .

I have a 5 cfm Robinaire 15500 Vac Master that I bought new @ Johnstones Supply . It was on sale for $145.00 new, never opened in the box. I think though it is not only the cfm but also the size of the motor . The Robinair has a 1/3 hp motor . My JB DV- 85 N is a 3 cfm pump with a 1/2 hp motor with a blown shaft seal and still pulls down quicker than the Robinaire

I really liked the JB pump . Bought it new on the Bay . Used it one time a the shaft seal blew . Pump was "supposedly" NEW. I believe it was a refurb ... looking back now . Stay away from the Bay for critical purchases such as pumps , micron gauges .... etc.

My 2 cents

-LMB

[Stewie007]

Well, the freeze can happen during the initial pull down rather than the remainder after that initial air mass is removed. I did a little bit of research to confirm it, however I don't think anyone should really be worrying about it at these pump sizes.

Lets compare it to Cycling. The stronger cyclist wins the mountainous stage of the Tour de France because he can climb the hills more effectively. However, the sprinter typically has better burst speed. So when the flat part of the stage begins, the sprinters rush out ahead. Then the mountains arrive, and the climbers take over. This is of course ignoring the 'roids and doping.

Basically, if you follow my logic, the pump with the 1/2HP motor is more efficient at evacuation than the 1/3HP motor despite the higher CFM when you get into deeper levels of vacuum. It seems pretty logical to me with the given information.

[Xeon th MG Pony]

Well where at it lets discus oil qualities too, I use a fairly thick vac oil, it is harder on the pump when it first starts but gives an excellent over all vac due to the thining effect as it warms!

[LMB]

http://www.centurytool.net/DVO_24_JB.../jbidvo-24.htm

All I would ever use . A bit pricey but well worth it to me

[plzdontbetaken]

Thanks for all the information guys. I haven't pulled the trigger yet but I think I am going to go with the Robinair 15600... mainly because of the price. It seems to have the lowest cost by a fair bit of any of the reputable branded pumps yall mentioned.

[LMB]

Key word being "reputable" Not a bad choice at all ! Good brand with a good warranty . Keep fresh clean oil in it at all times and keep the outside wiped down and clean and that pump will out last YOU !!

Good Luck!

-LMB

[Stewie007]

Cheers. You should be happy with that one.