New Vacuum Pump - need your advice

[lior307]

Hi guys ,

I have an opportunity to buy this Vacuum Pump.
It is a Two Stage , 1.5CFM (50Hz) , 25 Microns , 1/4HP .

Is this a good pump for Vacuuming my Phase ???
Here is the Picture:



Here's the Link:
http://www.worldvalue.cn/Products_item_big.asp?id=24

IS this pump will be good enough for Vacuuming a Phase change ???

[barbus]

Hi, I can't give much advice on that pump have never used them, but if it's for light phase work I'm sure it will do the trick, better than a compressor!
I would suspect it's more than capable of sucking the life out of a small phase system.

[Nosfer@tu]

I cant say how strong a vacume you need to pull.

I found these threads for you..

http://www.under-the-ice.com/forums/...7&t=138&hilit=
http://www.xtremesystems.org/forums/...d.php?t=104454

maybe that will give you the information you need.

because I dont know if that pump is cabable of pulling 25 microns as in max.
Or if that is how strong it is and then over time builds up more.

Hope it helps.

[tiborrr]

This one will do it's job very well!

[sdumper]

I would go with this one (15300) its a 2 stage 3cfm made by robinair its cheap and dependable.

http://www.testequipmentdepot.com/ro...2561?ref=gbase

[lior307]

I can get ONLY the Same Vacuum Pump but with 3CFM (85 l/min , 1/3 HP , 25 Microns )
Here is the Link:
http://www.worldvalue.cn/Products_item_big.asp?id=25

(the Difference Between the 1.5CFM to the 3CFM is about $100 .
1. What will the 3CFM Model give me Besides Less Vacuum time ??

2. Do i need a Better Vacuum Pump for a Cascade ??

[sdumper]

Originally Posted by lior307

I can get ONLY the Same Vacuum Pump but with 3CFM (85 l/min , 1/3 HP , 25 Microns )
Here is the Link:
http://www.worldvalue.cn/Products_item_big.asp?id=25

(the Difference Between the 1.5CFM to the 3CFM is about $100 .
1. What will the 3CFM Model give me Besides Less Vacuum time ??

2. Do i need a Better Vacuum Pump for a Cascade ??

It just saves some time but you are ok with 1.5cfm

[SexyMF]

That vac pump is fine. In fact a normal fridge compressor works. A couple of hundred micron works. There is a good deal of sentiment here that you need a crazy low vaccum for many hours and triple purge vacuum cycles to make things work. It's just not needed.

[lior307]

BUT is this 1.5CFM (25Microns/ 1/4HP) Vacuum Pump is enough for Cascade ??

[sdumper]

Originally Posted by lior307

BUT is this Vacuum Pumpis enough for Cascade ??

Yes

[ruffus]

oh ya it will work for all y want it to as i have a 1.5cfm that i bought when i first started building and it is still running good but i did buy a better one after i started to build system for customers

[ultralo1]

Originally Posted by SexyMF

That vac pump is fine. In fact a normal fridge compressor works. A couple of hundred micron works. There is a good deal of sentiment here that you need a crazy low vaccum for many hours and triple purge vacuum cycles to make things work. It's just not needed.

The purpose of a deep and long vacuum is to make them last, not only to work. The deep vacuum is to remove as much moisture as possible. Moisture in the oil leads to acid, acid leads to winding failures.

The purpose of the triple nitrogen sweep is three fold
1: reduce moisture
2: speed vacuum times
3: let the water that has frozen thaw so it can be vacuumed out

To understand number 3 you need to place a cup of water ina bell jar and pull a vacuum on it. You will see that as it boils off ice crystals form around the cup. Once the pressure is brought back up in the jar they will thaw more easily.

[[XC] gomeler]

Let's use our heads real quick. How much internal volume do our systems typically have? Maybe a cubic foot for a casacde? Compare that to a typical home HVAC system which must have at least a cubic foot of condenser if not more. Those 3 cuft/min vacuum pumps are great if you are vacuuming down something HUGE. I have a 1.5cuft single stage vacuum pump and I've never had moisture problems outside of tainted POE oil. Just change out the vacuum pump oil frequently and it'll keep on purring away.

Originally Posted by ultralo1

The purpose of a deep and long vacuum is to make them last, not only to work. The deep vacuum is to remove as much moisture as possible. Moisture in the oil leads to acid, acid leads to winding failures.

The purpose of the triple nitrogen sweep is three fold
1: reduce moisture
2: speed vacuum times
3: let the water that has frozen thaw so it can be vacuumed out

To understand number 3 you need to place a cup of water ina bell jar and pull a vacuum on it. You will see that as it boils off ice crystals form around the cup. Once the pressure is brought back up in the jar they will thaw more easily.

QFT.

[SexyMF]

The purpose of a deep and long vacuum is to make them last, not only to work. The deep vacuum is to remove as much moisture as possible. Moisture in the oil leads to acid, acid leads to winding failures.

The purpose of the triple nitrogen sweep is three fold
1: reduce moisture
2: speed vacuum times
3: let the water that has frozen thaw so it can be vacuumed out

Not to be trite but our systems are never employed long enough to worry about acid eating windings.
A filter/dryer will take out the tiny amount of moisture in a DIY system.

Most people just stick a hair dryer on the compressor to heat it up during vacuuming and shake it around a bit.

I started out using two freezer compressors in series. Never used nitrogen and only ever vacuum once.
My rigs worked fine.

[ultralo1]

Originally Posted by SexyMF

My rigs worked fine.

I am sure they do your are a good builder, I was just letting you know what he crazy, long deep vacuums are for Technically.

QFT.

Dont know what it means.

[wdrzal]

Vacuum pumps CFM ar rated @ free air,, ,,,,,,,,so a system that has 1.5 cfm volume ,a 1.5 cfm pump will get most (98%)of the non-condensables out in the first minuite. If the sytem has 3 CFM it takes 2 minuite to remove 98%. Once the vacuum gets deeper the CFM rating plummets. When you start to get below 2000 microns things slow down. This is where breaking the vacuum with dry nitrogen helps, so does removing valve cores, and large diameter short hose work best. At very low absolute pressures restriction are very critical on how fast non-condesables are removed. Mainly air which is mostly nitrogen 78%,20.9 oxygen,and little CO2.

One thing if you understand the correct procedures ,have the proper tools, and you want to get into this field to earn a living,you sould do very well.

[lior307]

Finally i bought the 3CFM / 25Microns , 1/3HP 85L/min .

I paid an extra of $25 over the 1.5CFM and i took it .

Here is the Vacuum Pump i bougth(50 Hz Version):


http://www.worldvalue.cn/Products_item_big.asp?id=25

[wdrzal]

A 2 stage pump is good.........I can't commet on that brand but a 1/3hp thats rated down to 25 microns sould work nicely.