Using CO2 as a purging gas instead of Nitrogen

[KickedGinger]

Does anyone use c02 to purge with while welding instead of nitrogen?
Is nitrogen drier? or is c02?
We have a tank of c02 for blowing out condensers and have always used c02. I have never really questioned what we should use but I want to be a better tech and part of that is using the right equipment.
They use c02 as a refrigerant so it must be ok to use as a purging tool right??
Let me know guys!
thanks

[jpsmith1cm]

Does anyone use c02 to purge with while welding instead of nitrogen?
Is nitrogen drier? or is c02?
We have a tank of c02 for blowing out condensers and have always used c02. I have never really questioned what we should use but I want to be a better tech and part of that is using the right equipment.
They use c02 as a refrigerant so it must be ok to use as a purging tool right??
Let me know guys!
thanks

I have used both and I cannot tell a difference between the results.

Some try the argument that CO2, in the presence of water, forms carbolic acid. This is true. Since we're evacuating the system to remove moisture, I don't see this as a major issue.

Depending on the CO2 grade that you buy, it may or may not have a significant quantity of moisture in it.

I like CO2 because there is a LOT more of it per can. I DON'T like it because that thing is HEAVY dragging it up to and across the roof.

[Capz]

CO2 is a corrosive gas and should not be used.

[Capz]

But it is ok to drink it but you wouldn't if you knew what is in it or should say what use to be in it prior to the soda bottlers pushing for higher purity beverage grade co2. I was in the ind gas business for 27 years. I can't count the amount of times I had to dump large co2 tanks full of product due to high levels of a poison gas. (The name escapes me, I been away from this stuff for six yrs). This gas would rise to the top of the tank and would not liquify but never the less, if a sample from the tank after a 20 ton delivery came back positive, we would be called out to dump it. Funny thing is, Coke never shut down. They kept filling soda. But keep in mind, product withdrawal was from the liquid side or bottom of the tank and the -5F liquid is vaporized with steam or electric heaters.

[KickedGinger]

CO2 is a corrosive gas and should not be used.

Can you back this up with evidence?
It cant be that bad if there is a big push for c02 as a refrigerant.

[Capz]

I'm not a scientist or a metallurgist, I cannot back it up. I do know co2 cylinders are required to be retested every 5 years rather than 10 yrs as for nitrogen, argon because it is considered corrosive. I was taught not to use co2 in refrigeration systems. I'm old school, try and do things correctly & safely. If co2 is okay to use why hasn't it been accepted for the last 30 years as a purge gas? I never read one time anywhere where is can be substituted for nitrogen. Have you? But I do know co2 is much heavier than nitrogen. I'd never for anything but blow out dusty condensers. Would really suck as a leak tester in a pressurized system, too dense.

[syndicated]

CO2 is considered an inert gas under normal conditions.
It is used for MIG welding but it can make steel more brittle due to the CO2 reacting to the high temps.
I'd be reticent to use it as a shielding/purging gas for brazing copper without proof it won't react with the joint in the long term

[duckman373]

Don't CO2 racks use stainless pipes?

[BALloyd]

Don't CO2 racks use stainless pipes?

High side is stainless. Low side is copper. From what I have seen. Makes sense given the price of stainless.

Sent from my SGH-I747M using Tapatalk 2

[mspanky]

Beverage grade co2 cannot be used as a refrigerant due to it's many contaminants. The grade used in racks is sometimes called Coleman grade.

[MicahWes]

CO2 is NOT corrosive in its pure form.

[Pascone10]

ALL tanks are to be hydro tested every 5 years.. Some ( Firefighting tanks etc.) that are not made of steel or aluminum must be disposed of after 15 years.. other then that as long as they pass hydro are good to go.

But in response to capz I never heard of a hydro on a tank longer then 5 years.. I mean air is not corrosive and that needs to be done every 5 years..

[syndicated]

CO2 is NOT corrosive in its pure form.

It is when heated during welding!

[Capz]

But in response to capz I never heard of a hydro on a tank longer then 5 years.. I mean air is not corrosive and that needs to be done every 5 years..

Typical high pressure steel cylinders for nitrogen, argon, etc every 10 yrs.

§ 180.209 Requirements for requalification of specification cylinders.

(a) Periodic qualification of cylinders. (1) Each specification cylinder that becomes due for periodic requalification, as specified in the following table, must be requalified and marked in conformance with the requirements of this subpart. Requalification records must be maintained in accordance with §180.215. Table 1 follows:

(b) DOT 3A or 3AA cylinders. (1) A cylinder conforming to specification DOT 3A or 3AA with a water capacity of 56.7 kg (125 lb) or less that is removed from any cluster, bank, group, rack, or vehicle each time it is filled, may be requalified every ten years instead of every five years, provided the cylinder conforms to all of the following conditions:

(i) The cylinder was manufactured after December 31, 1945.

[pherman]

Beverage grade co2 cannot be used as a refrigerant due to it's many contaminants. The grade used in racks is sometimes called Coleman grade.

I recall in a Hill Phoenix Secondary class them saying that you could use bev grade CO2 if you didn't have any or couldn't get Coleman grade and it would be OK.

[pherman]

But I've eaten and slept since then so.....

[Pascone10]

Typical high pressure steel cylinders for nitrogen, argon, etc every 10 yrs.

§ 180.209 Requirements for requalification of specification cylinders.

(a) Periodic qualification of cylinders. (1) Each specification cylinder that becomes due for periodic requalification, as specified in the following table, must be requalified and marked in conformance with the requirements of this subpart. Requalification records must be maintained in accordance with §180.215. Table 1 follows:

(b) DOT 3A or 3AA cylinders. (1) A cylinder conforming to specification DOT 3A or 3AA with a water capacity of 56.7 kg (125 lb) or less that is removed from any cluster, bank, group, rack, or vehicle each time it is filled, may be requalified every ten years instead of every five years, provided the cylinder conforms to all of the following conditions:

(i) The cylinder was manufactured after December 31, 1945.

Interesting.. I learned something new. Thanks for posting the link.

[eng&tech]

Beverage grade should NEVER be used with any CO2 refrigeration system!! There is to much moisture in a beverage grade CO2. You should use Coleman Grade or Instrument Grade, the idea grade should be 99.99% pure and free of moisture and non-condisables. With some secondary CO2 systems you can use industrial grade as long as its you run it though a liquid filter/dryer before you put it into you system. Please remember there are three types of CO2 system currently being used all over the world inculding the USA and Canada.

USA and Canada
CO2 Secondary - Over 60 currently installed for low temp operating pressure's of 175 - 250 psig depending on load
CO2 DX Cascade Systems - Over 50 currently installed. this is a cascade system using an HFC on the upper cascade and CO2 in the lower cascade operating pressure - 400 to 500 psig on the high side (+20 condensing) 200 - 250 psig (-20 SST)

Both of these systems are subcritical and use only copper pipe. Just like any refrigeration system we must use a dry system without non-condensables or moisture.

The last type of CO2 is Booster system they are the one's that operate at the highest pressures. They use black pipe or SS on the high side from the rack to the condensor/gas cooler back to the rack. They use L and K copper inside the store, but this type of system is HFC free. Can I get an AMEN!!!

[KickedGinger]

Sounds like C02 as a purging/pressure test tool gets a failing grade.
Maybe I should make the switch.
I just purchased a new micron gauge and 1/2 evacuation manifold with 1/2 hoses!! (in the mail)
Cant wait!

[Grayline]

Only the science and medical Grade contains 0.000% moisture
Also Co2 is a simple compressed gas so having a containment of it would be ridicules it would be so heavy it wouldnt make sense