The bullnose, or POL, connector has a left-hand thread that screws into the cylinder valve. This means you turn it anti-clockwise to do it up, and clockwise to remove it. It’s also known as a male connector. All high pressure regulators have this type of fitting.
Gas enters the regulator through the inlet, which for high pressure regulators usually measures 10mm (⅜ inch).
Locking nut
High pressure bullnose regulators are fitted with a locking nut which you tighten with a gas spanner. Although the connection needs to be secure, be careful not to do up the nut too tightly as this can cause damage.
Always use a proper gas spanner of the correct size to avoid damaging the nut.
Control knob
Some regulators have an adjustable control knob which lets you raise or lower the gas pressure coming out of the regulator. You turn the knob clockwise to increase pressure, and anti-clockwise to decrease it.
Being able to adjust the gas flow gives you greater precision – for instance, different metals may need varying amounts of heat when welding.
Hose failure valve
Many high pressure regulators are fitted with an automatic hose failure valve which shuts off the gas if the hose develops a leak.
The valve sticks out at an angle from the regulator to let the hose rotate freely while in use, which reduces the chance of it becoming tangled. This is particularly useful if you’re moving around, for instance when using a tar kettle or roofing torch.
Gauge port
Most high pressure regulators have a hole, known as a port, where you can attach a pressure gauge.
Many regulators come with a gauge already fitted but you can also buy them separately to add on, as long as you have a spare port.
Gas pressure gauge
A gas pressure gauge, also called a manometer, is a device used to measure the pressure of gas, usually in bars or millibars.
The gauge consists of a round dial indicator and a threaded nut for connection to a port.
Twin pressure gauge unit
Some regulators have two gauges. The inlet pressure gauge shows the pressure of gas as it enters the regulator from the cylinder. As the gas is used up, the pressure in the cylinder drops. This indicates how much gas is left in the cylinder, so you can line up a replacement tank.
The right-hand gauge measures the pressure of the gas as it leaves the regulator to enter the appliance. This gauge lets you precisely control the pressure by turning the control lever or knob until the desired pressure is displayed on the gauge.
Another type of gauge, called a flow gauge, can be found on medical regulators supplying oxygen. This lets you check how many litres of oxygen per minute are flowing out of the regulator.