Natural gas smells for a reason

At 3:05 p.m., a shop instructor at New London School in Texas turned on an electric sander.

Within minutes, about 300 students and teachers were killed in a March 18, 1937, explosion that remains the worst catastrophe at a school building in the United States.

The culprit: a faulty pipe connection that leaked natural gas — odorless and undetectable — allowing a buildup in the enclosed crawl space that ran the length of the 253-foot building.

Texas soon adopted a law requiring an odorant be added to natural gas when delivered for use — a foul smell that alerts people to the presence of gas — and the practice quickly spread worldwide.

Adding a sulfur compound that’s often likened to the smell of rotten eggs continues to save lives, including in Colorado Springs.

The slightly sour smell of the odorant prompts up to 500 residents a month to call Colorado Springs Utilities to report possible gas leaks — more in the fall when furnaces are turned on after being idle through the summer.

Gas can leak from ovens, water heaters, fireplaces, furnaces — any appliance that uses gas, and the pipes that supply them.

Springs Utilities doesn’t charge for a home inspection after the smell of gas is reported, and inspectors are available round-the-clock.

Utilities uses roughly 24,000 pounds of odorant annually. At a cost of $24,700 a year, it’s probably one of the cheapest safety precautions available.

“We add .85 of a pound per million cubic feet (of gas),” said Colorado Springs Utilities’ customer operations supervisor Paul Brizal Jr., who oversees the odorizing process.

There’s not much to it, actually. The liquid drips into a type of wick in pipelines at five locations along Marksheffel Road from Black Forest to Security where the city takes delivery of the gas. As the gas flows through tanks at the odorant stations and into pipelines, it passes over the wick, rich with odorant, and picks up the substance.

The process is computerized and constantly monitored.

“We know at any given time how much gas is flowing,” Brizal said. “The flow computer tells us to add so much.”

Gas can ignite when there is 5 percent to 15 percent gas to air. If it’s more or less than that, it won’t ignite.

That’s why it’s important for people who smell gas in their homes to get out immediately and call for help, Brizal said. Don’t turn on a light or use a phone — the static electricity from such devices could ignite the gas if it’s present in the right concentration.

Don’t open a window to ventilate, he added, because the additional air could bring the gas-air mix down to the ignitable range.

Odorant is added so that a 1 percent presence can be detected, he said.

But Utilities workers don’t add the odorant and forget about it. They make weekly rounds to the ends of pipelines, 25 locations, to make sure the odorant is maintained throughout the system. To do that, they use a computer smaller than a briefcase that takes readings of the odorant’s potency.

For an inspection, call 448-4800.

“It’s never normal to smell gas,” Brizal said.