In the good ol' days it probably didn't matter much if your equipment or technique wasted shielding gas.   With the rising cost of electricity and consequently the extraction of argon from the atmosphere, it now becomes more important to reduce gas waste.  To do that we first have to identify the causes of shielding gas waste.  Here are some of the main culprits:

  1. Gas flow rate is set too high
  2. Gas flow meter is inaccurate
    1. Flow resistance in hose
    2. Decreasing pressure from cylinder
  3. Gas dispensing at torch is turbulent
    1. Standard collet design not as efficient as gas lens
    2. Pressure or flow rate is too high for cup size
    3. Cup size is too large for flow rate
  4. Pressure buildup in connecting hose from flow meter to solenoid valve when valve closed
    1. Causes "gas surge" when valve opens
      1. Numerous starts in tack welding and short runs
      2. Peak flow much higher than desired
      3. Turbulent initial gas stream
    2. Length and diameter of hose stores pressurized gas
    3. Long pre-flow times to stabilize flow rate
  5. Leaks in the gas delivery system.

Each one of these issues has a different cause.  Taking them one at a time, we can devise a comprehensive plan for eliminating shielding gas waste.  Here are some possible causes:

  1. The common sense "more is better" belief does not apply to shielding gas.  In fact, the higher the pressure and flow rate, the more turbulence and shorter the length of laminar flow from the end of the cup.
  2. Single stage regulators do not maintain a constant pressure as the cylinder contents deplete.  That can lead to inaccurate flow rates from your flow meter.  Also, variables in gas flow resistance in the torch hose will affect the delivered flow rate.
  3. Turbulent shielding gas flow at the torch will not only waste gas, but pull atmospheric contaminants into the gas column, reducing the weld quality.  Gas lenses help distribute gas more evenly, but you must still match the flow rate to the cup size and amperage setting.  Too much pressure or flow will cause turbulence, so in general the least amount of pressure and flow, the better. 
  4. Initial high pressure and flow rate when opening the solenoid valve disrupts laminar flow and may degrade arc starts and initial melt pool formation.  It may take several seconds to stabilize, which wastes gas and could impede welding progress.  When performing tack welds this becomes and extravagant waste, considering the small percentage of welding time compared to gas flow time.  Beginners also tend to make short runs with many starts and stops, further reducing the efficient use of shielding gas.
  5. Leaks may occur at fittings and possibly within the regulator / flow meter.

In light of the causes and their underlying mechanisms, we are now ready to propose solutions: 

  1. Carefully set and document flow rates for each combination of amperage and cup size, as well as weldment geometry and metal type.  Pay attention to weld quality and seek the optimum flow rate for each setup.  Practice on prototypes or mock-ups to find the optimum flow rate.  Document your results to compile your own reference of starting parameters.
  2. Dual stage regulators are more accurate and less prone to variation from decreasing cylinder pressure.  This becomes even more important with lower flow rates in TIG processes, especially for specialty welding on small items with miniature torches.  However, gas pressure in the cylinder diminishes so slowly that you will not notice any change in a typical welding session.  Each time you begin a new session, you will adjust your flow rate according to your situation, and that should stay constant through the session.  Flow rates may be measured at the torch cup via external flow meters.  This eliminates the variables in your torch hose length and configuration. 
  3. Gas lens delivery systems on the torch head provide more uniform flow patterns and extend the length of the laminar flow region.  This allows for longer electrode stick-out when necessary for hard to reach welding areas or for greater visibility.  Don't use the "one size fits all" approach to welding, but adjust your cup size, length, and electrode stick-out for each situation.  Experiment with different combinations and document your settings and results to find the optimum configuration.  Approach this in a systematic way to accelerate learning.
  4. The gas delivery equipment from the cylinder to the welder can make a big difference.
    1. Dual stage regulators may help reduce gas surge. They are also immune to changing output pressure and flow rate due to depletion in the cylinder.  Uniweld offers a relatively inexpensive model designed for argon, the RHT8014.  This video explains the differences between single and dual stage regulators:
    2. Lower output pressure single stage regulators will significantly help. Inexpensive regulator / flow meter valves may be calibrated at 50 to 70 psi, which is much higher than necessary for argon in the TIG process. More expensive regulators operating in the 20 to 25 psi range are more appropriate.  Harris offers one that is about five times as expensive, but still reasonable considering the cost of the welder, gas bottles, and shielding gas.
    3. Harris also offers a "gas guard" regulator that specifically addresses the gas surge problem.  This document explains the concept and viability of the product.  Here is a video that shows the difference with a graph of gas surge from a non- gas guard torch versus one with the gas guard regulator:
    4. Reducing the internal diameter and shortening the length of hose from the flow meter to the solenoid valve reduces the amount of high pressure gas that will escape once the solenoid valve opens.  Installing an orifice near the solenoid valve also reduces the flow rate in the initial surge.  This may reduce the amount of pre-flow time necessary before striking the arc.  The "gas saver system" advertises significant savings, and the above link describes the theory and critiques alternative approaches, such as the Inert Gas Guard system from Harris.
  5. Check all connections with soapy water and look for bubbles.  Buy quality components from reputable suppliers.  Avoid homemade connections using hose clamps and hose barbs.

Finally, after analyzing the problem, its causes, and possible solutions, the question remains: Is it worth the bother?  That ultimately depends upon your concept of value, not only in money but in time and quality of your welds.  Consider that if you have already spent thousands on the welder, gas cylinder, cart, filler rod, safety equipment, fabrication table, fume extraction system, and all the rest, an extra several hundred dollars for a more capable gas delivery system doesn't seem like much of a premium.

Also, if you are starting out with TIG welding, you will learn faster with less frustration if you can control more of the variables.  Gas surge and inaccurate flow rates may complicate the learning process, as it may be hard for you to identify those variables with little to no experience.  More control means more focused practice, especially if you experiment and document your results.

Finally, if you are value conscious, you may become inhibited towards practice if you think of the wasted shielding gas with each tack weld or short run.  This might have a negative effect on your enjoyment and put a cap on your progress.  You may want to eliminate as much friction in the learning process as possible at the outset by purchasing the best system you can afford, rather than suffering with lower quality equipment to save money, thinking you will upgrade later. 

For those of you who are content to trust another person's judgment, here is what I decided to do, based upon my understanding of the concepts involved and what I deem to be practical.

  1. Purchasing large gas cylinders and installing some sort of surge prevention will eliminate perceived waste and encourage me to experiment with different scenarios.  I will know that I have done as much as feasibly possible given my level of equipment and knowledge.
  2. Buying a Harris 355-2 argon regulator will provide lower delivery pressure and should ensure a quality build, which should last for a long time, considering the warranty for the regulator is seven years.
  3. Purchasing a separate Harris 301-80 Inert Gas Guard Regulator (IGG) will allow me to place this device at the gas inlet on the back of the welder, with a 90 degree elbow to distance the IGG from the gas bottle, so that any gas pressure stored in the supply hose from the Harris 355 regulator will be controlled by the Inert Gas Guard regulator.  This should totally eliminate any gas surge upon opening the solenoid valve.
  4. The diameter and length of the supply hose will not matter and I could use the one that was supplied with my welder, except for the fact that my new setup requires a male to male hose. That means the Gas Saver System isn't necessary for my setup, since the Inert Gas Guard will control any buildup of pressure in the supply hose.
    1. The flow meter that came with the welder should be adequate for back purging from my backup gas cylinder, when it is necessary to protect the back side of a weld due to thin walls or total penetration of the heat affected zone, especially with stainless steel.
    2. The Back purging system will be completely separate from the welding gas system, with a separate bottle, regulator, flow meter and hose.
  5. Given that all these components are subject to leakage, especially when handled often and when conditions vary from extreme temperatures in the summer and winter, it will be prudent to check all connections with soapy water periodically, perhaps every month or more often when environmental changes challenge the equipment.

There you have it.  Although buying an extra cylinder and associated regulator and surge suppression system adds significantly to the cost of my welding setup, I believe these acquisitions to be a sound investment in the future.  Gas prices will only increase, and I want that cost to be manageable.  At the same time, I want to encourage practice and learning during the beginning stages of my welding experience.

Last modified: Thursday, 1 August 2024, 7:43 AM