Nitrogen… an often misunderstood SAFETY gas that many fear and for good reason! Imagine you have a flammable liquid that has a Flash-PointP<100°F and you worry about static or other ignition sources causing an event inside your storage container… what can I do to lessen the risk of a fire/explosion in the headspace of my container? Lower the Oxygen concentration to a level that the atmosphere will not support combustion (e.g. Limiting Oxygen/Oxidizer Concentration). So we need an INERT gas that will CLEANLY displace the oxygen from the space. Enter in… Nitrogen. It is the most widely used inerting gas around the world because it is very efficient at creating Oxygen Deprived Atmospheres!!! So on one hand it is a great “safety gas” in terms of preventing fires/explosions in flammable services; however, on the other hand it is also the leading killer of workers within permit-required confined spaces. But how about a space that is NOT a PRCS or even a Confined Space (CS) but a space that houses the fixed water-based fire suppression systems, such as a sprinkler room? Does the installation of a Nitrogen Generator and it’s receiver/storage tank create a potential atmospheric hazard within this space? Let’s break this down…
Today I had one of these units removed from service after an operator entered the sprinkler room for an unrelated reason and his meter, set to alarm at 20.0% O2 began alarming. At first, he thought the device he was retrieving and had been running for a few minutes had created a CO issue. But after further investigation, the meter used to check the room did not pick up any CO but showed an O2 level of 20.0%. This, of course, got our attention and our PSSR was stopped and our investigation ensued.
Background:
Over the past decade, using N2 in fixed water-based fire suppression systems has become the rage! It works very well and extends the life of the system for many many years and reduces performance issues. So again, N2 helps us maintain one of our most fundamental fire safety systems. But when we install a generator and its receiver in a space that was NEVER designed for such a hazardous gas, we may be asking for trouble. I have researched many of these “fire suppression” systems and have been unable to identify their safety instrumented systems (SIS) or any guidance on where these systems can be located and if located indoors – any type of ventilation specifications for the space. Here are the questions we should be asking BEFORE we allow one of these systems to be installed in a “sprinkler room”…