Why Simple Orifices, Flowmeters or Regulators,
Mounted at a Wire Feeder Gas Inlet - DON'T WORK!

Attempts to solve weld start gas surge problems with an orifice, flowmeter or flow control regulator mounted at the wire feeder are frequently rejected by welders since they produce unacceptable results.  Not understanding the relatively complex cause of these issues has frustrated welding foreman and welding engineers to blame welder attitude - when the welder was probably right!

A review of some of the problems created by using any type of flow control mounted at the wire feeder in attempt to solve weld start surge flow and gas waste follows:

An orifice can be placed at a wire feeder gas inlet to set the steady state shielding gas flow rate.  Surge is reduced, however with this approach there is not enough extra gas at the weld start that creates a greater less obvious problem observed by a welder! This need was clearly defined in a 1982 patent by Stauffer, see Tech Details below. A FABRICATOR'S EXPERIANCE FOLLOWS

Seeing the excess starting spatter welders attempt to compensate for the lack of sufficient extra start gas by increasing the steady state flow rate. Although increased steady state flow can help, it's not as good as supplying extra gas quickly employing higher pressure and flow. A welder may set much higher steady state flow rates than needed.  Gas waste from the start surge is reduced but the overall gas flow rate is set higher than needed, wasting gas! In addition to insufficient gas at the weld start to purge the weld start area, gun nozzle, etc (often causing welders to drill out or remove the added orifice.

Management often blamed welders "For not caring about gas waste when orifice flow control was implemented."  In fact when hearing these complaints I often accepted the management view! Until in the past 12 years working with fabricators and welders, I understood the issue. It was eliminating the needed extra gas required to purge the gun nozzle and weld start area of moisture laden air. For the welder it was like starting in air! They, like myself, had occasionally started welding when using cylinder gas and forgot to turn the valve!  Those starts were similar! Welders may not know the reason but know they need more gas so they ask to have the steady state gas flow rate increased or do it themselves. Seeing an improvement they leave the high steady state flow rate, wasting NOT saving gas!

Note, if a flow control orifice is used at the pipeline gas drop to set gas flow and conventional gas delivery hose is employed significant excessive gas waste and inferior weld starts occurs.  Our GSS can save 80% of that waste and improve weld start quality.  The GSS  works fine with flow control orifices placed at the pipeline drop if the pipeline pressure is consistent and the orifice properly sized.

Production Example of Lack of Extra Start Gas

If sufficient shielding gas is not provided at the start, welders may try to compensate by using higher overall gas flow.  A bar joist manufacturer was using flow control orifices mounted at the wire feeders.  Argon/CO₂ shielding gas is supplied in a pipeline through about 15 feet of gas delivery hose.  The flow control orifice established the flow at 45 CFH.  However the welders wanted higher flow rates with some even drilling out the orifice!  The welding engineer wanted to avoid wasting shielding gas. With this flow setting arrangement where control is mounted at the feeder next to the gas solenoid  there is insufficient extra gas provided at the weld start.  This lack of extra gas prevents proper purging the weld start  area of moisture laden air.  

Tests were made to check weld performance and potential shielding gas savings using two cylinders of  gas on two adjacent welders instead of from their pipeline gas supply.  One welder was set with their standard flow control orifice system and a regulator providing a pressure that matched their pipeline pressure, 50 psi.  The other with a regulator/flowmeter (also of a 50 psi design) using the same 15  foot length gas delivery hose GSS without their flow control orifice.  Both steady state flows were set at their normal 45 CFH.  Since welders stand side by side, it was easy to observe the weld start quality!   Instantly the welder using the GSS  noticed  improved  starting.  After about an hour with observably better results with  the  GSS welder  the  welding engineer suggested we lower its shielding gas flow  to 35 CFH!  The same improved weld start quality was observed and the welder was "happy."  In fact even though we lowered the steady-state flow to 35 CFH there was still about the same controlled amount of extra gas available at the start (that stored in the GSS hose when welding stopped.) The higher start gas flow rate established by the surge flow orifice in the GSS maintained the higher flow for a short time at the start.   This higher start flow rate quickly flooded and purged the weld start area of moisture laden air.  It was this air that was casing excess spatter and lack of start shielding on all their other welders! After about 4 hours of observation it was obvious the spatter at the weld start was less with the GSS.  We also measured a reduced use of shielding gas of ~35%.   After several months of testing to check this one system during windy days etc, this shop now has GSS's installed on all 50 welders!   

Bottom Line - - "Some extra gas flow at the start is very beneficial."  In addition, after about a year of use their bulk gas supplier called to see if their business had turned down since they were using 30+% less gas- it had not!

Note: Any flow control device installed right at the feeder, be it an orifice flow control, a flowmeter or a flow control regulator will have the same lack of sufficient initial shielding gas to purge the weld start area.

STARTING PROBLEM WITH FLOWMETER PLACED AT WIRE FEEDER

A review of the shielding gas flow rates in a shop with ~100 welders revealed the amount of excess gas flow each welder was using!

DETAILS:

A shop with 100 MIG welders tried to reduce gas waste by installing flowmeters at the wire feeders. These were connected by a hose to a 50 psi shielding gas pipeline. Most of the flowmeters were model L-32 (shown at right)  read accurately when connected to a 50 psi gas line, so the flow readings are direct. 

As when mounting an orifice at the wire feeder, this approach essentially eliminates all surge flow BUT insufficient gas is available at the weld start to purge air from the weld area and MIG gun nozzle.  As expected, the welders tried to compensate (which they really can not fully accomplish) by increasing the steady state flow!

The following was observed:

• ~50% of the welders were set at ~50 - 55 CFH.  None were found lower than that flow level.

• ~25% of the welders were set near the top of the flowgauge, which for this model is 70 CFH.

• The remaining ~25% had the flow ball pinned to the top of the flow tube.  In our Lab we have measured flows with this model flowmeter of 150 CFH when the needle valve is opened about a half turn more than with the ball hitting the top of the flowgauge!

In trying to compensate for the lack of sufficient extra start gas the welders set the steady state flow far higher than needed.  Any flow over 50 to 60 CFH is just pulling air into the gas stream and is counter productive!

Note in the other bar joist plant mentioned above using a quick initial pure of air at a short high gas flow rate a 35 CFH steady state flow rate was sufficient! Note when they used the GSS the maximum peak flow rate was below a level that creates excess turbulence, unlike typical standard flow control systems!

REGULATORS PLACED AT WIRE FEEDER LACK NEEDED STARTING GAS PURGE

Flow control regulators placed at the wire feeder gas inlet have been sold to limit peak gas flow rate. Some of these, unlike low pressure devices, operate at pressures above that necessary to maintain "automatic flow compensation."

However they have the same problem as simple orifices or flowmeters or frankly any device mounted at the gas inlet on a wire feeder - LACK OF NEEDED PURGE GAS AT WELD STARTS.

The lack of a quick purge of moisture laden air from the weld start area and MIG gun nozzle causes less obvious problems! Excess starting spatter is the most obvious.

Welders may not understand the technical reason but they see high starting spatter levels and realize they need more gas. Since many of these regulators are adjustable for flow, they increase the steady state flow. It may help but cannot provide enough extra gas purge quickly. They also wind up INCREASING, not DECREASING shielding gas use!

SOULTIONS:

There is a simple and proven effective solution to this problem:

Use Our Patented Gas Saver System, (GSS):

Put the flow control back at the pipeline or high pressure cylinder flow control and install our inexpensive patented GSS that provides sufficient extra start gas purge. On pipelines that can be a flow control orifice.

The GSS does NOT alter the system pressure so maintains "automatic flow compensation" built into quality flow controls since the MIG process was introduced in the 1950's.

The GSS quickly provides a controlled amount of purge gas at a maximum flow rate that DOES NOT CASUE EXCESSTUBULENCE.

The GSS retains ~85% less gas when welding stops reducing the "gas blast" gas volume by that amount, saving significant gas.

MOST IMPORTTANT: Welders LOVE the improved start achieved with the GSS !

1. TECH DETAILS:

   The need for some extra gas at the weld start was clearly defined in a 1982 patent by Stauffer. As he outlined, a sufficient quality of shielding gas must be quickly delivered at the start of a weld to purge moisture laden air from the weld start area and MIG gun nozzle. The figure right is from his patent. He added a rather large reservoir (item 112 in the figure) in his device because it operated at lower pressure. Although the lower pressure feature caused flow variations I have a specific experience in Pulsed MIG welding where weld starts were significantly improved over the "gas blast" caused by conventional flow controls.

   This complex device solved the weld start problem but like some other even electronic flow control devices that cost over $2000, it caused other less obvious problems!

WANT MORE DETAILS OF ANY OF THESE PROBLEM DEVCIES? - EMAIL

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