Smith H698 Regulator-Mount Reverse Flow Check Valves (Pair)

Essential Safety for Oxy-Fuel Operations

When you are under the hood or handling a cutting torch, the last thing you want to worry about is the integrity of your gas supply. The Smith H698 Regulator Mount Reverse Flow Check Valves are an absolute must-have for any welder using oxygen and acetylene, propane, or other fuel gases. These small but mighty devices are designed to stop one of the most dangerous occurrences in gas welding: the reverse flow of gas. This happens more often than you might think—usually when a tip gets clogged with spatter or when one of your tanks runs dry in the middle of a job. Without a check valve, the gas from the full tank can push its way back up the empty hose and into your regulator, creating a ticking time bomb of mixed gas.

The Smith H698 pair gives you peace of mind by acting as a one-way street for your gases. They allow oxygen and fuel to flow freely to your torch so you can work without interruption, but the moment pressure drops or tries to reverse, they snap shut. The valves are spring-loaded to close automatically if back-pressure is detected or if flow pressure drops below 1/2 PSIG. This instant reaction keeps your regulators, and more importantly, you, safe from the potential of regulator explosions caused by mixed gases.

Designed with the welder in mind, these valves are incredibly easy to install. They screw right onto your existing regulator outlets—standard "B" size fittings (9/16-18) that fit almost every standard regulator on the market. The set comes with one valve for oxygen (green, right-hand thread) and one for fuel (red, left-hand thread), so you can't mix them up. Because they mount at the regulator, they protect the most expensive part of your setup and keep the hoses isolated from the cylinders. They are built with heavy-duty brass to survive the knocks and bumps of shop life.

Don't take chances with your safety setup. While these check valves stop gas from flowing the wrong way, remember they are different from flashback arrestors (which stop fire). For the best protection, many welders use these check valves on the regulator to prevent gas mixing, ensuring that your equipment lasts longer and your work environment remains safe. Whether you are a hobbyist in a garage or a professional in a fabrication shop, the Smith H698 check valves are a small investment that offers massive protection.