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Single Stage Vs Two Stage Gas Regulators

Understanding the difference between single-stage and two-stage gas regulators, we have laid out some key information on single-stage and two-stage regulators.


A gas pressure regulator is a device that attaches to the delivery valve on the cylinder. The regulator is designed to work at the maximum pressure for a given cylinder and regulate the output- delivery- to a lower pressure for use.


Hi-Lo UK Two Stage gas regulator with welding background

The difference between single-stage and two-stage gas regulators


Single Stage Regulator:

High-pressure gas from the supply enters the regulator through the inlet valve. The gas then

Hi-Lo UK Single Stage Elite gas regulator

enters the body of the regulator, which is controlled by the needle valve. The pressure rises, which pushes the diaphragm, closing the inlet valve to which it is attached, and preventing any more gas from entering the regulator. The outlet side is fitted with a pressure gauge. As gas is drawn from the outlet side, the pressure inside the regulator body falls. The diaphragm is pushed back by the spring and the valve opens, letting more gas in from the supply until equilibrium is reached between the outlet pressure and the spring. The outlet pressure, therefore, depends on the spring force, which can be adjusted using an adjustment handle or knob.


The outlet pressure and the inlet pressure hold the diaphragm/valve assembly in the closed position against the force of the large spring. If the supply pressure falls, it is as if the large spring compression is increased allowing more gas and higher pressure to build in the outlet chamber until an equilibrium pressure is reached. Thus, if the supply pressure falls, the outlet pressure will increase, provided the outlet pressure remains below the falling supply pressure. This is the cause of the end-of-tank dump where the supply is provided by a pressurised gas tank.


With a single-stage regulator, when the supply tank gets low, the lower inlet pressure causes the outlet pressure to climb. If the spring compression is not adjusted to compensate, the valves can remain open and allow the tank to rapidly dump its remaining contents. In other words, the lower the supply pressure, the lower the pressure differential the regulator can achieve for a given spring setting.


Two Stage Regulator:


Hi-Lo UK Two Stage Elite gas regulator

Two-stage regulators are two single-stage regulators in one that operate to reduce the pressure progressively in two stages. The first stage, which is preset, reduces the pressure of the supply gas to an intermediate stage; gas at that pressure passes into the second stage. The gas now emerges at a pressure (working pressure) set by the pressure-adjusting control knob attached to the diaphragm. Two-stage regulators have two safety valves for

added protection. A major objection to the single-stage regulator is the need for frequent torque adjustment.


If the supply pressure falls, the outlet pressure increases, necessitating torque adjustment. In the two-stage regulator, there is automatic compensation for any drop in the supply pressure. Single-stage regulators may be used with pipelines and cylinders. Two-stage regulators are used with cylinders and manifolds. Two-staged regulators are recommended for applications that require a constant outlet pressure for the life of a gas cylinder.


Diagrammatic representation of the function of single and two stage regulators

Working with Hi-Lo UK

Our sister company Hi-Lo UK prides itself on its versatility. They have the ability and expertise to manufacture bespoke products that are used in a vast array of industrial processes. Along with a full stock of standard gas-cutting and welding equipment.


With advanced technology and ultra-modern manufacturing techniques, we can offer to you the most reliable, heavy-duty and hard-wearing products. Also, the confidence that you are dealing with a market leader when it comes to safety.


The Hi-Lo brand which has one of its manufacturing facilities based in York operates with state-of-the-art CNC machines and is capable of producing high-quality cutting nozzles and brass fittings for a wide range of applications from the fabrication shop to heavy steel mill equipment.


Hi-Lo UK has created a made-in-Britain range of single and two-stage elite regulators manufactured under BS EN ISO 9001 and conforms to BS EN ISO 2503. The key features of Hi-Lo UK single-stage and two-stage regulators include:

  • 2 years warranty.

  • 300 bar service.

  • Manufactured under BS EN ISO 9001.

  • Conforms to BS EN ISO 2503.

  • Alloy bonnet for high strength.

  • High contrast, easy-to-read gauges.

  • Made in Britain.

  • Available in bottom or side entry.


Looking for more information on gas equipment? Our expert team are available to help you get more information and knowledge on gas equipment. Get in touch.


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