Posted June 13, 2018
CNG Fueling Station Emergency Shutdown Devices – How many and where?
Seems like a pretty straight forward question, right? I mean, come on, there are codes, standards and guidelines that cover this stuff from organizations like the National Fire Protection Association (NFPA), the Petroleum Equipment Institute (PEI) or various State departments and, for the most part, when I read the information from any of the afore-mentioned organizations or departments, it makes sense. However, there is enough ambiguity that, when someone asks the question…”How many manual emergency shutdown posts do we need in my CNG Time fill plan and where?” the infamous standard consultant answer of “It depends” rolls easily off my lips.
First and foremost, this is not a system performance, durability or cost issue, it’s a safety issue. Also, it doesn’t matter if the time fill station is being used to fuel refuse trucks or school buses, the safety considerations and concerns remain the same.
NFPA 52-Vehicular Gaseous Fuel Systems Code seems clear when they state that an emergency shutdown device shall be provided within 10 feet of the dispensing area and also greater than 25 feet from the dispensing area. I applied a bold font to, and underlined, the “shall” because in standards, codes and regulations a “shall” means do-it versus a “should” which implies a strong recommendation. Of course, the “dispensing area” at different fuel stations could represent very different footprints so, interpretation is interjected and safety could be compromised. A shutdown device 10 feet from the dispensing area, for fast access, and one greater than 25 feet from the dispensing area, probably for access that is clear & safe of dangerous gas release, seems reasonable, unless the time fill dispenser area consists of two or more multi-post lineups making for a significantly large dispensing area and the person trying to get to the emergency shutdown device is on the opposite end of the area from where the device is located, 10 feet outside the dispensing area.
PEI committee recommendations are a bit different stating that the shutdown device should be close enough to the fueling area to be quickly accessible when standing in or near any fueling position, there should be a clear path to the device and, within a reasonable distance (approximately 100 feet) of every fueling post. Again, makes reasonable sense but, not enough to make specific system design decisions without interpretation.
So, what to do? InsightFuel approaches it on the side of over-engineering the shutdown device locations and to err on the side of personal and property safety and providing the person(s) who needs to activate the shutdown device ample opportunities (locations) to reach a device quickly while exiting for their personal safety. In doing that, we find that all the conditions in the various standards, codes and recommendations are met and typically exceeded.