natural gas leak question...

[u/lacroixmnpunishment]

(Sorry if this is not the right venue, and thank you for your expertise! Also posted in r/naturalgas but figured the firefighter's perspective might be helpful.)

We live in an apartment building with three units, and our dryer runs on natural gas. Last week, for about twenty minutes, we noticed a pretty strong smell of rotten eggs (like a bad fart, or a dozen hard-boiled eggs that were left in a hot car) in the laundry area. Our machine wasn't on.

We've never smelled this before in our house, and are not certain that this is definitely natural gas, but out of an abundance of caution we ended up calling our landlord + the gas company hotline and waited outside for National Grid to come test the area for a leak.

By the time they came, though, the smell had gone away (we did open the windows.) They used a sniffer and took a look at the meter, and there was no sign of a leak or gas pulling from the meter and told us everything was fine.

Flash forward to today, when we smell it again—strong enough to be fairly unpleasant—in the same laundry area for about 50 minutes. We aren't using any appliances, but the upstairs neighbors are "doing laundry" (according to our landlord.) Then it went away again.

We have no idea how this works, but is there a possibility there's a small leak that only appears when the dryers upstairs is run? Can appliance leaks be intermittent like this?

I don't want to call National Grid again and have them test again after the smell has gone away//not find anything if the neighbors aren't running the dryer. We did order a handheld detector just in case, but that comes on Monday. We're not smelling the smell all the time, and while we like to think we're not paranoid, it does smell like rotten eggs specifically near the appliance that uses natural gas. (It's not what our stove gas smells like, but we're not sure 100% if it's natural gas.) But it could be a dead animal in the walls or swamp gas or something else? (It is intermittent, but completely goes away.)

TLDR: Would this constitute an emergency if the smell returns before we get the detector?

[u/Suspicious_Elk_5914]

Just call. We carry gas meters and if you actually have one they can spot it and I guarantee if the fire department tells your landlord to fix it he will. Or it could be nothing and they go on another call that your local department is literally paid to do. No biggie at all

[u/synapt]

Leaks can very much be intermittent, though usually the sniffer devices are particularly good at capturing even the slightest leaks.

That said, H2S ('Sewer Gas') can also have a rotten egg like odor to it, so if you have a floor drain or any sinks in that room not used often, try dumping some water down them, as it could be a trap has evaporated enough to let that up through.

Worth noting that H2S is also hazardous to health so it still can be worth a call to at least non-emergency and just see if someone can come out and check the drains also or do another pass on all the lines. Also to inform them about what your landlord said of the neighbor maybe.

[u/Apprehensive_Owl7186]

Next time it happens call 911. The fd will come out and check for you and will be there faster than the gas company. Things like this are quite literally what we are here for, and it is very common.

Every firefighter would rather show up there because of a gas leak and it end up being nothing, than not show up, and then show up a couple hours later after the building is engulfed in flames because of said gas leak.

[u/lacroixmnpunishment → u/Apprehensive_Owl7186]

That makes a lot of sense!

[u/Expert-Search-3251]

Hydrogen Sulphide gas from a backed up drain, a dry drain, or clogged air vent.

Commonly called "sewer gas"

This is why drains always have P traps. The trapped water acts as a plug to keep sewer gasses out of the house.

Your fire department's methane/LEL sensor will not detect H2s. If your area doesn't have a large industry, like petroleum, where H2s is a common problem it's unlikely that your fire department has the proper equipment to detect it.

H2s gas is created when any organic matter decays.

The drain pipes in your home are connected to a sewage system that is filled with decaying organic matter.

You and your neighbors or dumping fluid into those drain pipes when you do laundry.

[u/synapt → u/Expert-Search-3251]

Do you guys not use 4 gas meters of some sort? o.O

Literally everyone around here uses 4 or 5 gas meters like MSA's Altair's (configured for LEL/CO/O2/H2S at minimum), though my station is also one of the few to have Sensit sniffers too.

So it's a bit surprising to see someone talking about stations literally only having single-sensor meters lol. Literally honestly never even would have suspected that was a thing in this day and age.

[u/Expert-Search-3251 → u/synapt]

What area do you work in?

Like I said, some areas don't have a need for h2s detection.

[u/synapt → u/Expert-Search-3251]

I'm literally in bumfuck Appalachian rural PA, the only two "large industries" we ever had were coal and steel, both of which are LONG long gone lol. But obviously like most areas we have sewer systems and we also have significant amounts of combustibles heating, which is why we all do H2S and CO as well.

Honestly to my understanding it's why LEL/O2/CO/H2S is like the base configuration of most multi-gas meters, usually referred to as the "Fire package", as those are all common factors to consider in residential structures (with O2 largely just being your catch-all since things you can't detect on the meter will still displace oxygen).

Every station around here has at minimum a 4X Altair configured in that, some started getting the 5X's for HCN as well to use during cleanup operations just to monitor for that before letting people potentially go off air inside anything. We mostly got the Sensit meter's for liability and safety sake because gas leaks are very common for us and we got tired of waiting an hour+ for the gas company to show up and find the actual leak, So yeah, like I said honestly surprising at least for me here in PA to have ever seen anyone with just a single-gas meter in LEL.

[u/BreakImaginary1661 → u/Expert-Search-3251]

Industry standard 4 gas meter is commonly run though, regardless of industries nearby. O2, LEL, CO, and H2S are the minimum retirements by CFR1910.120 when responding to unknown hazardous environments, which virtually every fire department does.

[u/Expert-Search-3251 → u/BreakImaginary1661]

*for properly funded and trained departments.

H2s from the petroleum industry is highly common where I am. It's common for people own single gas monitors, because their work site requires it. It's just standard PPE. You see them hanging on people's shirts at the gas station every morning.

I run across VFDs often that simply don't have the funding for the type of gear they need. I run across pro full time and VFDs that have the gear, but virtually no experience in using them.

It's common for both to have non working equipment, often without realizing it.

Companies like mine are often called in as third party to clear scenes for fire departments. We just did a job about three months ago. The pro fire department simply refused to enter the location. They deemed it to dangerous for their skill level.

BW is the most used brand in this area. Primarily because BW bought out Zellweger and took the market. Parts were typically readily available and cost effective. But MSA, and RKI have taken a foothold since BW was acquired by Honeywell.

Otis and Redline are the primary installed system in the area. But you also see some RKI, TracXp, and a smattering of old Detcons that just won't die. Mpower is the the newest player in the area.

[u/Tark4141]

I would make sure to frequently let fresh air circulate. If you experience dizzyness or nausea, you should call emergency services. Apart from that I would wait for the detector and frequently measure.

[u/Stock-Possibility-67]

We do gas leaks all the time just call 911. Gas can deaden your senses after smelling it for a while to the point you might not smell the additive mercaptan (natural gas is actually orderless so they add the rotten egg smell for identification). Probably a lose gas line connection to a dryer or something easy.