They say that any chain is only as strong as its weakest link. In gas welding operations, you don’t want that weakest link to be the gas regulator. It provides crucial elements of functionality to any mode of welding you are performing. Single-stage, multi-stage. Inert non-combustible gas, combustible gas. While all welding gas regulators may look the same to an uninformed glance, there are differences between these different categories that must be recognized and complied with to provide safe, effective, and economical welding applications.
Gas flow and pressure are the essential elements that the regulator controls. It does this by means of a diaphragm and spring combination that provides the mechanism for gas flow control. The pressure within a gas cylinder is usually between 200 and 300 bar, with one bar equaling 14.5 psi. The regulator functions as the step-down chamber, transforming that cylinder pressure to a drastically lower output pressure to the welding torch – typically around 1 ⁄ 4 bar or 3-4 psi.
Gas flow and pressure

That conversion can either be accomplished in one step, which provides a less stable or constant pressure. In these single-stage regulator operations, the output pressure must be manually adjusted to maintain the required specific pressure for the welding operation at hand. As the pressure in the cylinder drops (as the gas inside is depleted), the output pressure rises conversely and must be manually reduced with the regulator. A two-stage regulator, as its name indicates, accomplishes this pressure reduction in two steps.

The first step (conducted in the first-stage regulator) reduces that 200-300 bar pressure to a steady 10-bar pressure in a non-adjustable process.

The second stage is then used to adjust that 10-bar flow to the precise pressure and flow required for the welding task being performed.

A third, less commonly mentioned, form of regulator is the flow meter regulator, which is essentially a two-stage regulator. This regulator’s second stage is replaced by the flow meter, which controls flow rather than pressure – as measured in SCFH (Standard Cubic Feet per Hour). The flow meter is typically chosen for TIG and MIG applications.

Regulators for combustible gases (Acetylene, Propane, Propylene etc.), usually have left-hand (counter-clockwise) threads. The left-hand thread is indicated by little cuts in the flats of the Hexagon. Regulators for non-combustible gases (Oxygen, Argon, CO2 etc.), usually have right-hand (clockwise) threads and as such do not have the cuts on the Hexagon.

While this may seem initially boggling, the selection of the most appropriate regulator for your intended application can be determined by a simple matrix, based on the component factors that must be considered.

Those factors are

  • (a) gas type (discussed above)
  • (b) application (whether high-pressure for oxy-fuel applications or low, controlled pressure for TIG , (for example)
  • (c) gas flow rate (a related but distinct factor from pressure)
  • (d) equipment compatibility (the gas-to-regulator correspondence mentioned earlier but also similar compatibility for all torches, hoses, and fitting)
  • (e) safety considerations and manufacturer’s recommendations.
Regulators for combustible gases
appropriate regulator

The relatively simple matrix is as follows:

Suitable Welding Applications Regulator Type
Cutting, brazing Single-stage
TIG, MIG Dual-stage
Oxy-fuel welding High-pressure
MIG, TIG Low-pressure
Exotic or highly reactive gases, specialized applications Specialty
Selection and use of the appropriate air regulator is only the beginning of its life in your welding toolkit. To ensure the longevity of the regulator and its attached equipment, regular maintenance is required. Humidity is an inevitable consequence of using compressed gases. Eliminating that moisture from the hoses, torches, and regulators is essential to safe and effective welding. Just like most integrated systems, the longevity of any part is dependent on its maintenance and occasional replacement of components such as the regulator’s diaphragm and spring. Replacing those components before they reach a failure point or even reduced effectiveness can ensure uninterrupted positive welding results. For any further questions or concerns regarding the proper choice and use of an air regulator for your welding application(s) – questions that can’t be answered by a review of the manufacturer’s literature – feel free to consult with your dependable, local purveyors of all things welding-related, Eureka Oxygen.
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