On Sunday, September 21st, a gas explosion demolished a vacant fourplex in north Minneapolis. This was the second north Minneapolis home to have this happen since March. I’ll go out on a limb and say I’m sure both explosions were caused by natural gas leaks, which were both the results of copper thieves doing their thing. In both cases, neighboring residents reported strong natural gas odors before the explosions. Natural gas is obviously dangerous, but really, how dangerous?
I believe that the utility companies cater to the lowest denominator when it comes to public service announcements about gas. I’m sure we’ve all heard the saying; “If you smell gas, get out!” I’ve heard the same radio commercial many times saying not to turn on a light switch, use the phone, a computer, etc… just leave the area immediately. I’m not going to say this is bad advice – better safe than sorry, I’m sure, but I’d like to share some of my experiences with natural gas.
To start, I find gas leaks at a lot of homes. These leaks are very small – sometimes so small I can’t smell the leak unless I’m very close to the pipe. I use an electronic gas detector to find these, and I wet the suspected leak with a gas leak detection solution to verify that it’s really a leak, and not just a false reading by my electronic gas detector. If I see little bubbles, I report it as a minor leak, and recommend repair by a plumber. I’ve never evacuated a house because of a leak, and I’ve never called the gas company.
How serious are these minor leaks? To find out, I did a little testing at my own house. I feel like I need to preface this with Don’t Try This At Home (there). I started my test by spraying soap and water on a gas fitting and slowly loosening the connection until bubbles started forming (pictured below, left). At this point, I could barely smell gas by putting my nose to the pipe. I held a lighter to the gas leak… nothing. I opened the nut more and more, and was finally able to get a small blue flame about half the size of the flame on my lighter. At this point, I could faintly smell it from a few feet away, and got a bubble about two inches wide (pictured below, right).
With this much gas coming out, about half of what a cigarette lighter would emit, I would recommend immediate repair and would also notify the owner of the leak so they could get it fixed right away. For the smaller leaks that are barely noticeable, I note them in my inspection reports and recommend repair, but I don’t consider them an imminent safety hazard. So there, I said it; not all gas leaks are hazardous. If you walk in to a room and smell gas, that’s a problem, and you should heed the gas company’s advice.
Post update 12/18/15: The gas company classifies leaks in three categories:
• Hazardous – a leak that is an immediate hazard that requires immediate repair
• Potentially hazardous – a leak that is non-hazardous when detected but needs to be monitored and repaired before it becomes a future hazard
• Non-hazardous – a non-hazardous leak that is expected to remain non-hazardous.
That information can be found here: http://www.centerpointenergy.com/en-us/residential/in-your-community/media-center/touchpoint?sa=mn#safety
Reuben Saltzman, Structure Tech Home Inspections – Email – Minneapolis Home Inspections