Optimized orbital TIG welding results thanks to a PPM oxygen analyzer?

The functionality of a digital oxygen analyzer or oxygen meter lies in its capacity to precisely measure the amount of oxygen present in a volume, in this case, the inside of a tube. As soon as a pre-defined minimum threshold value is reached, the oxygen meter sends an electrical signal to the TIG welding power source which then starts the welding cycle.

The PPM reader is not part of the standard configuration of our automated orbital TIG welding machine because, depending on the customer's application, it may not be necessary. Yet it is up to the customer to decide whether he wishes to acquire this device or not.

PPM oxygen analyzer
The oxygen analyzer can be purchased at a later point in time causing no troubles regarding the connection since it just needs to be plugged in to the auxiliary socket on the front panel of the power supply and that’s it.

AXXAIR also offers you the possibility to rent the PPM reader if you need it punctually for a specific project.



When a discoloration of the inside of a tube is intolerable, an oxygen analyzer becomes indispensable

In an earlier article, “How to avoid coloration of a weld”, we saw that in some areas of application, a discoloration on the inside of a tube is intolerable since it cannot be amended afterwards due to limited access or the inner surface condition (electro-polished).

These areas of application include for example the industry of pharmaceutics or semiconductors, as "high-purity" is mandatory in these fields.

In many cases, the welder tends to use too much gas when purging to ensure that all the oxygen has been flushed out and that the inside of the tube is sufficiently inerted, in order to avoid having to rework or even worse, throw out the work piece. This method has the benefit of being simple, but it most definitely has a number of downsides.

Needless to say, scrapping a work piece or having to rework it after the welding is expensive, but a very pure gas such as argon is a significant cost factor that is often underestimated. 

With a digital oxygen analyzer, a welder can save purging gas while being sure to achieve high-quality, repeatable and oxidation free welds.

The set threshold value is usually less than 60 PPM (parts per million) for stainless steel which translates to 0.05% oxygen in a given measurement volume. This value, the PPM level is to be defined by the operator according to the industry’s specifications. 



How does the oxygen analyzer work?

Orbital closed head microfitOne end of the oxygen meter is plugged in to the auxiliary socket on the front panel of the orbital TIG welding power supply, the other end goes into the tube where it will measure the gas level in the interior of the tube.

Our oxygen meter works with zirconium oxide. At a high temperature, certain ceramics, including zirconium oxide, conduct electricity due to the expulsion of the oxygen ions.

This characteristic can be used to determine the oxygen concentration present in a gas mixture. A zirconium oxide disc is mounted between the gas to be measured and a reference gas (usually air) in a heating element.

Electrodes are connected to each side of the disc. Any difference in the oxygen concentration between the two sides of the disc will cause a voltage to be transmitted via the electrodes. It is thanks to this voltage that a threshold value can be defined to initiate the welding process.



An oxygen PPM reader is a piece of equipment that can prove to be indispensable for certain applications of TIG welding in order to guarantee a weld that is neither oxidized, nor porous. When welding stainless steel tubes without inert gas, bubbles forming in the weld bead when the weld bath solidifies can cause porosity. Nonetheless, the decision of acquiring an oxygen analyzer when buying a TIG welding power source should be carefully weighed up to determine whether it is needed or not. 

Find all our advice on how to choose your welding power source in our free guide.

Download the welding power sources guide

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Écrit par
Alicia Wendland

Marketing Manager