Dangers of natural gas
Natural gas is the most widely used source of energy for household heating and cooking, and for the most part it's quite safe. However, homeowners need to be vigilant about the risk of natural gas leaks. Every year, people die because of undetected or unrecognized gas leaks. The most common cause of death is asphyxiation, but sometimes a gas-filled basement will explode into a fireball that quickly consumes the entire house.
Though natural gas, or methane, isn’t poisonous, it displaces the levels of oxygen we need to breathe. At sea level, the atmosphere contains 21 percent oxygen, and you need at least an 18 percent concentration to breathe normally. As the methane displaces the oxygen in an enclosed space, you’ll start to get dizzy and disoriented, lose concentration and coordination. As oxygen levels continue to decrease, you’ll feel tired, even exhausted. Your heart rate and breathing will increase. Eventually, you’ll feel nauseated, lose consciousness and stop breathing.
Methane gas is highly combustible, with a small amount producing lots of heat. But it requires just the right mixture with oxygen to cause an explosion in an enclosed space. Less than 5 percent of natural gas in the air isn’t enough to ignite, and more than 15 percent doesn’t have enough oxygen, according to experts interviewed by the Indianapolis Star following a deadly explosion in the city. So for an average home, at least 10 percent of the gas needs to permeate the air before it can combust.
Also keep in mind that some leaks may start in your basement, which means that if you start to smell gas on the second floor, a large amount may have already accumulated downstairs. It's important to evacuate the premises, and call in the experts to repair the gas leak.
How to detect gas leaks
If you suspect a gas leak in or around your home, look for these warning signs:
A sulfur or rotten egg smell
In its pure form, natural gas is colorless, odorless and tasteless, so utility companies add a foul-smelling, harmless substance called mercaptan to increase the chances you’ll detect it if even a small leak occurs. Mercaptan contains sulfur, so that’s why natural gas smells like rotten eggs.
Hissing sound or blowing emanating near or from pipes or appliances
Natural gas must be pressurized to travel through the pipes and reach the home. A loose connection fitting, a cracked pipe or a failed seal will allow natural gas to escape, which may be indicated by the blowing or hissing sound.
Flames, if a leak has ignited
An open flame can result if a leak from a natural gas pipe or appliance has found a source of ignition, such as pilot light or electrical spark.
Dead or discolored vegetation in the vicinity of a gas line
Natural gas is lighter than air and will rise if it escapes, so if the surrounding vegetation is otherwise green, a patch or line of dead or discolored vegetation can indicate a gas leak underground.
Dust or dirt blowing from the ground or bubbling in wet or flooded areas
These leak indicators occur because natural gas is lighter than air. If you notice blowing dirt or bubbling coming from under the soil, it can indicate a leak in an underground pipe. An underground gas leak can be especially dangerous because the soil can filter out the sulfur odor that cues us to the presence of natural gas.
Natural gas detectors
Consider buying a natural gas detector. You can buy some models for about $40, and some alert you to the presence of most types of combustible gas, including methane, propane and butane. You’ll find still other combination detectors that alert you to carbon monoxide.
While it may be tempting to locate the source of the leak yourself, you should take certain emergency actions prior to identifying the leak source or attempting a gas leak repair. In the majority of cases, you should leave the task of finding the source of the leak and making repairs to an experienced professional.
What to do if you find a leak
If you suspect your home has a natural gas leak, it’s imperative that you take the following actions:
Leave the area immediately and call your natural gas utility
Finding a gas leak is a serious issue that risks the safety of your home and its occupants. Call the utility company and request they send an inspector or technician to evaluate the problem. It’s better to be safe than sorry, and this safety precaution will not result in any kind of cost or fee to the homeowner in most cases.
If the natural gas utility is unavailable or if your home uses natural gas supplied by a tank that’s filled by a refill service, call the local fire department. Firefighters are trained and equipped to respond to natural gas leaks.
Do not operate any electrical device or appliance, including cell phones
Operating electrical devices such as light switches, garage doors or electronic devices — even personal electronics — can inadvertently cause a spark or a static electrical charge that can ignite the leaking gas.
Do not smoke, use an open flame, matches or lighters
Again, these could serve as ignition sources for the leaking gas.
Do not try to locate the source of the leak
If a leak is suspected, it’s possible that flammable gas is entering the home and causing a potential fire risk. It’s better to evacuate the area and call an experienced professional rather than trying to find the source of the leak yourself.
Do not try to shut off the supply or gas-fired appliances
Unless you’re a trained gas utility technician, gas-fitting plumber or HVAC technician, don't try to shut off the gas supply or gas-using appliances in the event of a gas leak. Trying to shut off the gas may cause a spark that could ignite the leaking gas or damage pipes and appliances if done improperly.
Do not start vehicles
A hot exhaust or a spark from a vehicle in the vicinity of a natural gas leak could become an ignition source.
Once the leak has been identified and stopped by the utility company, fire department or another qualified professional, you’ll need to hire a qualified professional to repair the leak. For most pipe-based leaks, a licensed plumber that offers gas supply pipe services will likely be the most qualified professional to make the repairs.
For leaks that originate from home appliances like stoves, call a large appliance repair specialist. For leaks that originate from heating equipment, hire a licensed HVAC company to make repairs.
How to prevent gas leaks
The best way to address a gas leak is to prevent one from happening in the first place. Many of the issues that cause gas leaks can be prevented by performing regular checkups on your home’s gas plumbing or gas-fired appliances.
Check connections regularly
About every six months, check the connection fittings on your gas-fired appliances and heating equipment. If you don’t feel you have the right experience to do so, call a highly rated appliance service, heating and cooling company or plumber to perform these semi-annual checks.
Use only licensed professionals
Since plumbing gas lines requires training and experience that can only be provided by a licensed professional, it’s always recommended to hire a licensed plumber to perform any maintenance, repairs or upgrades to plumbing that acts as natural gas lines.
Call 811 before you dig
If you plan to excavate any areas of your property for landscaping or other improvements, always be aware of where gas lines are located and avoid digging near gas lines. If you’re unsure of where the gas lines are located on your property, call the gas utility before excavating.
Calling the 811 Know Before You Dig hotline will route your call to the appropriate local utility, which can locate and mark gas line locations free of charge. The 811 website also offers a state-by-state guide to help homeowners get their gas lines marked before excavation.
Staying safe around natural gas
• Follow the manufacturer’s guidelines when setting the temperature on your gas water heater. The maximum temperature should generally be set between 110 and 120 degrees to prevent burns or scalding. Use extreme caution when installing a water heater, or call a professional.
• If you use a gas fireplace or gas logs, make sure you keep the chimney damper open. Even with gas fireplaces, make sure your chimney is adequately maintained and free from obstructions. If the fireplace features a key-operated valve, remove the key when the fireplace is not in use.
• If your clothes dryer uses gas, periodically check the lint trap and dryer vent to ensure both are clear from obstructions.
• Ask a qualified HVAC technician to check your heating system at least once a year. A technician should not only make sure the system is operating properly and efficiently, they should check for proper combustion and venting of exhaust gases such as carbon monoxide.
• Install a carbon monoxide alarm. If not installed or maintained properly, gas appliances can create dangerous buildups of carbon monoxide, a colorless, odorless and tasteless gas. You can purchase a carbon monoxide detector for as little as $20. Many municipalities, utilities and fire departments also offer carbon monoxide detectors free of charge.
• Never store flammable liquids, such as paint thinners or gasoline, near gas appliances.
• Never store combustible materials, such as rags, paper or cardboard, near gas appliances.
• Never attempt to reroute or divert natural gas lines yourself.
• When building new structures on your property, such as home additions, sheds, garages or other outbuildings, call 811 before you dig or build to ensure the structure is not built on top of a gas line.
• Follow the manufacturer’s instructions and maintenance guidelines when installing natural gas appliances. Use only qualified technicians for repairs.
• If a flood, earthquake or other catastrophic event damages your home, always check for the odor of gas. If detected, call your local gas utility or fire department.
• Never use natural gas pipes to store clothing or other items. Hanging clothes or other objects from pipes near the ceiling, such as in a basement for example, creates an additional load on the pipe that can create leaks at the joints.
• Never allow children to hang or swing from natural gas pipes.