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price increaseNote: Argon Prices Increased over 50% in the past 2 yrs!
In 2014 PRAXAIR announced 35% and AIRGAS 25% increases.
A large fabricator recently told us they were put on allocation and will only be able to receive 70% of the past years Argon!

Our patented Gas Saver System (GSS ) can cut gas use in half by eliminating gas waste while providing better weld starts. It's time to cut your shielding gas waste!
Many thousands of GSS's are in use at industrial fabricators such as Air Products, Boeing, Caterpillar Tractor etc. See Partial User List.

MIG Shielding Gas Flow Rate Chart
(For Argon Mixtures and CO2
CLICK for FREE PDF of Chart with Expanded  Information 

For Metric (SI) units - Multiply CFH  x 0.472 =  liters/min
Note: MIG Gas Flow is SET in CFH NOT in psi  SEE Discussion Below

Click to See Video: MIG Shielding Gas Flow Settings

A customer recently said, "Can't understand why every MIG welder doesn't use your great Gas Saver System (GSS)?"  He continued, "Like the saying, build a better mouse trap and people will beat a path to your door."   I told him that only fits if they understand they have mice! 
Bottom Line:
If you're not using our, low cost, patented
GSS you have "mice!"  It saves about half the shielding gas used by eliminating the "gas blast" at every weld start. Compared to other devices tried in the past to save gas, welders like the GSS improved starts!

To maintain our focus on "Saving not Selling" shielding gas our patented products are sold direct and are "Not Available in Stores."

Check Gas Flow Accurately

With Our Portable Flowmeter

Check the gas flow exiting the MIG gun nozzle with our portable flowmeter (Part # WAT-PFM)

Our instructions outline a simple procedure to check flow coming into the feeder/welder and exiting the nozzle to check for leaks and excess gas backflow.

The following is a condensed comment received for a welding engineer, see full comment on purchase page:

"I received the portable flow meter and used it to measure the output on two robotic torches. I was able to show that our processes are not in control. ....  It will also help us ... troubleshoot future porosity problems. An additional benefit, of course, is that we will probably greatly reduce our gas consumption costs. Thanks for a great tool for a great price!"
CLICK FOR PURCHASE PAGE

We receive questions asking: "What MIG shielding gas flow rate should be used?"  Sometimes asking: "What pressure should be set?"    This is understandable since even the American Welding Societies 5 volume, 4000 + page "Welding Handbook"  has everything you would want to know about MIG welding (GMAW) but very little shielding gas flow rate recommendations! There are statements saying excess shielding gas flow creates turbulence and pulls in oxygen and nitrogen creating problems but no mention of what the maximum flow rate should be!  We have done the research and defined the maximum levels. 

MIG shielding gas flow is set and measured as cubic feet of gas per hour (CFH) NOT pressure in psi.  Unlike oxyfuel welding and cutting, MIG gas flow rates are very low.  The gas pressure in the hose going into a wire feeder/welder, while welding, typically varies from 3 to 8 psi.  Flow restrictions in the small size MIG gun and cable gas passages vary when welding.  This pressure changes as spatter builds in the gun nozzle and gas diffuser.  A significant pressure drop change occurs in the small gas passage in the gun cable as it is bent while welding. Since the gun cable gas passage often doubles as the hose holding the spiral wire liner-it partially clogs with copper flakes and debris.  Pressure must increase to offset these added restrictions.  A method of  "Automatic Flow Compensation" is built into all "quality" gas control systems to maintain preset flow rates as these restrictions occur. 

MINIMUM FLOW RATES:

A number of factors determine the minimum shielding gas flow rate needed.  The MIG gun nozzle size is an important factor.  Small ID nozzle sizes require less flow to get quality shielding.  Drafts are also very important as is the type of weld joint.

In a low draft environment when making a fillet weld the lowest suggested flows are usable.  The plates being welded help retain the shielding gas.  Shielding is more effective with the help of the gas retention at these low rates.  The vertical member is also effective in providing a natural block for drafts.

TYPICAL FLOW RATE RANGE:

For butt welds there is no vertical plate to help retain the shielding gas.  In addition there is nothing to help maintain the gas shield  when drafts are encountered.  Therefore the  gas flow rate needs to increase to assure quality gas shielding and proper weld coverage.  The range shown in the table is typical of that used in industry (or that should be used!)  As wire size, welding current and the gun nozzle to work distance are increased gas flow rates should increase.

MAXIMUM SUGGESTED FLOW RATE:

In the presence of drafts, higher flow rates can be used - up to a limit.  It is important to avoid creating Turbulent flow that will pull air into the shielding gas stream.  In 1893 Osborne Reynolds defined the flow rates that establish smooth Laminar flow (needed for quality MIG shielding) versus  Turbulent flow that causes moisture laden air to mix with the shielding gas stream.  Using that information and extensive tests The Welding Institute in the UK defined the maximum flow rates to maintain Laminar flow.  In a recent published article  the manager of welding R&D for Praxair states; "flow rates in excess of  50 CFH cause atmospheric gases to be pulled into the gas stream causing poor weld quality."  Click and see references numbers 3 & 4 on this web page.

Reinforcing the maximum flow rate values is unpublished research that defined flow rates needed to handle drafts.  In a 4 to 5 mph controlled draft using Argon based shielding gas and a standard 5/8 inch diameter MIG gun nozzle, 45 CFH flow rate had less internal weld porosity as measured by X-ray than 65 CFH flow rate.  This reinforces the need to keep flow rates below about 55 CFH with a 5/8 inch nozzle. 

WIND SHIELD:

When MIG welding, if drafts exceed about 4 to 5 mph, a wind shield or block must be used.  In some cases that can be as simple as positioning your body between the source of the draft  and the weld.  A simple wind shield can be made from sheet metal and held to the work with small magnets. Many welding codes limit gas shielding processes to welding with drafts lower than 5 mph.

During a "Best Practices" tour in Japan of bridge fabricators  we saw  gas shielded MIG being used at a construction site to butt weld large girder vertical seams.   Simple flexible wind shields were used that were moved as welding progressed. 

If drafts are an issue, a larger 3/4 inch ID nozzle and increased shielding gas flow can be used up to the suggested maximum of 65 CFH BUT NO HIGHER.

Unfortunately some folks believe; "If Some is Good, More Must Be Better" when it comes to setting shielding gas flow!  We have often seen flowmeters with the ball pinned to the top of the flow gauge tube.  Measurements of commercial flowmeters show with the needle valve opened wide flow rates can be 150 CFH- far too much for good shielding.  Also a fabricator recently called and said his welding gas distributor told him the 100 CFH flow rate they were using was fine!  It's NOT! We have two patented products that can help solve the problem. The first is our Gas Saver System GSS . It reduces the gas surge at the weld stat saving about half the gas being used. The GSS also limits the maximum flow to a level that avoids excess turbulence. The GSS will limit flow to about half the level that can be set on a flowmeter when the knob is opened wide. Click for Details
If it is desired to set flow rate limits to stay within Welding Procedure Spesifications (WPS) then our patented "Flow Rate Limiter and Lock" are just the ticket, Click for Details

Another problem with excess flow is the "Blast of Gas" that occurs at the weld start with conventional gas control systems.  We have measured peak flows at the weld start in excess of 250 CFH.

The graph on the left is from a production operation where the gas flow rate at each weld start exceeded 75 CFH for 4 seconds.  Osborne Reynolds defined that Turbulent flow takes some time to return to Laminar flow even after the flow rate is reduced.  Therefore it is probable Turbulent flow existed for 6 or 7 seconds.  Note when the company installed our patented Gas Saver System  peak flow was reduced to under 90 CFH and it was over 75 CFH for only about a second after the torch switch was pulled.  The GSS quickly provided enough extra gas to purge the weld start area but at a flow rate that did not create excess Turbulence.  The welder at this repair weld station immediately saw the benefit of the GSS as his welds are all ultrasonically tested.   He was having significant problems with weld start porosity and knew the high starting gas surge was a major cause.   After 6 months using our patented GSS  he said his porosity problems had been eliminated.  Note, it only takes about 2 1/2 % air being mixed into the shielding gas stream to exceed the 2% Nitrogen  some sources indicate will cause weld porosity.

SEE DETAILS OF THIS APPLICATION.

Why MIG Gas Flow in CFH NOT PSI?

MIG gas flow is set and measured in cubic feet per hour NOT psi. Unlike Oxyacetylene welding where pressures are set to control flow though a torch - in MIG welding much lower gas flow rates are used.  At these low flow rates, during welding, restriction changes occur due to spatter build-up in the gun nozzle and gas diffuser, the small gas passage in the gun cable is bent and looped, etc.  These restrictions could cause large flow changes.

When MIG was developed, the engineers designing the gas flow systems used a principle called "choked flow" that provides  Automatic Flow Compensation and maintains the preset flow regardless of the changing flow restrictions. "Choked Flow" works by the fact that gas velocity can not exceed the speed of sound.  That is why you see lightening before you hear the thunder!   If the low pressures needed to set the required flow were used, when the restrictions changed so would the flow; it could cut preset flow in half!  A minimum of 25 psi above a needle valve or flow control orifice is required to obtain "choked flow."   Unfortunately this is a much higher pressure than the 3 to 7 psi needed to flow the typical 25 to 30 CFH.  This high pressure causes excess gas volume to be stored in the gas delivery hose (from cylinder or pipeline to welder) each time welding stops.  This excess stored gas " blasts" out of the MIG nozzle at each weld start. This gas surge not only wastes a lot of gas but causes excess turbulence pulling air into the gas stream, creating inferior weld starts.  Our simple, patented GSS  solves both the gas waste and "gas blast" problems!

NOTE: Don't confuse CFH (cubic feet per hour) with the flow rate of an air compressor or the 850 Holley on my Street Rod which measure flow rate in CFM (cubic feet of gas per minute.)  For the Holley, that would be 850 CFM X 60 minutes/hr = 51,000 CFH!  Or for MIG welding, 30 CFH X hr/60 min = 1/2 CFM - pretty low flow rate!

Received an Excellent Question About How an Orifice or Needle Valve Can Set and Automatically Adjust to the Proper Pressure Drop to Maintain Consistent MIG Gas Flow?

The Answer is Detailed so a PDF was Produced:

CLICK TO SEE THE ANSWER:

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