Natural Gas Vehicle Institute (NGVi) wants to bring attention to an important requirement under NFPA 52, the installation code for natural gas vehicles. It states that any fuel container (cylinder) with a shut-off valve must also provide technicians with a way to determine whether pressure is still present in that container. This is vital to the safety of CNG technicians involved in the inspection and maintenance of heavy-duty NGVs. Otherwise, they leave themselves open to potential injury and death.

NGVi’s Executive Director Leo Thomason explained the need for this announcement. “This requirement has been a part of NFPA 52 since the version released back in 2016,” he says, “yet it’s been my experience that virtually no CNG-powered heavy-duty vehicles that I or our other instructors [at NGVi] have seen during our live, in-person training have had the capability to visually determine the presence of pressure inside their cylinders.”

In short, he says, that’s a big problem. 

Cylinder valves may fail while in the closed position, giving technicians the false sense that these cylinders have been defueled. Thomason says he knows of at least two vehicle technicians who have lost their lives in this type of situation. Each one attempted to remove a valve from a cylinder they thought was empty, only to be struck and killed by the valve due to the pressure that was released.

How can these dangers be avoided? Thomason offers three solutions: “One, have a pressure gauge in the PRD port on the cylinder valve. Two, have a transducer installed in the high-pressure portion of the fuel system that’s connected to a pressure-indicating device. Three, have a written procedure for determining cylinder pressure prepared by the CNG fuel system manufacturer or installer.”

For more information about how to ensure natural gas vehicle safety for your fleet vehicles, technicians, drivers, and the general public, please contact Natural Gas Vehicle Institute through their website, or by calling 800-510-6484.