Straight answers to the questions people ask most when choosing and using gas regulators.
What is the difference between a single-stage and a two-stage regulator?
A single-stage regulator reduces the cylinder pressure to the working pressure in one step. As the cylinder empties, the outlet pressure drifts slightly, so you may need to readjust it. A two-stage regulator does this in two steps and holds a steadier outlet pressure as the cylinder empties.
Single-stage regulators are simple and fine for most general work. Two-stage types suit work where a constant pressure matters, such as precise flow control, or long jobs from one cylinder.
Can I use the same regulator for different gases?
Not safely, unless the maker states it is designed for it. Regulators are made for a specific gas, or a group of gases, with the correct materials, pressure range and cylinder connection. Oxygen regulators in particular must be kept free from oil and grease.
The connection to the cylinder is deliberately different for different gases, so that a regulator cannot be fitted to the wrong one. Never use an adaptor to get round this unless it is made for the purpose and approved by the maker.
What do the two gauges on a regulator show?
The inlet (cylinder) gauge shows the pressure in the cylinder, and the outlet (working) gauge shows the pressure going to the hose. With a compressed gas such as oxygen or argon, the cylinder gauge gives a good idea of how full the cylinder is.
Acetylene is different. It is dissolved in a liquid inside the cylinder, so the gauge pressure does not show how much gas is left. Weighing the cylinder is the reliable way to know. Always check that the gauges are undamaged and read zero when the system is depressurised.
What is regulator creep and what should I do about it?
Creep is when the outlet pressure slowly rises even though you have not changed the setting, usually when the regulator is closed and not in use. It is often caused by dirt or damage on the valve seat inside the regulator.
It is a warning sign. Close the cylinder, release the pressure, and have the regulator checked or replaced by a competent person. Do not carry on using a regulator that creeps, because the pressure in the hose and the torch may go higher than you intended.
How often should a regulator be replaced or serviced?
There is no single answer, because it depends on the maker, the gas and how hard the regulator is used. Many makers give a recommended service life or inspection interval, and some regulators can be serviced by the maker.
Replace a regulator if gauges are cracked or stick, if it creeps or leaks, if the connections are damaged, or if it has been dropped or subjected to a flashback or a burst of oxygen. Keep a record of inspection, and do not try to repair it yourself.
What is a gas-saver regulator?
A gas-saver regulator is a type of shielding gas regulator that is designed to help reduce the amount of gas wasted, for example by limiting the flow or the surge when welding starts. The way it does this differs from one design to another, so read the manual for the one you are considering.
Whether it saves gas in practice depends on how you weld and how often you start and stop, so be cautious about claimed savings. Make sure it is made for the shielding gas you use and covers the flow range you need, and check the data plate and manual for its ratings.