Smoke Testing a Valuable Component of Contractor’s Diagnostic Toolbox

O’Fallon Sewer Service uses smoke testing to pinpoint sources of puzzling problems

Smoke Testing a Valuable Component of Contractor’s Diagnostic Toolbox

Leonard Earnest of O'Fallon Sewer Service

Interested in Location/Detection?

Get Location/Detection articles, news and videos right in your inbox! Sign up now.

Location/Detection + Get Alerts

In his more than 55 years running O’Fallon (Missouri) Sewer Service, Leonard Earnest has seen quite a few technological changes. He says the most significant might be the diagnostic tools, one being smoke testing equipment.

“We’ve done miracles with that,” Earnest says.

His company uses equipment from Superior Signal.

In one case, the company was called to a movie theater that had problems with mysterious odors ever since it was built.

“We discovered vents that were never hooked up,” Earnest recalls. “They were just loose in the wall. It was supposed to be venting outside, and it was just venting into the wall.”

In another case, a bank was on the verge of shutting down a branch because of odors, but smoke testing revealed the problem was the result of nails that had been driven into a sewer vent. Something like that can make a big difference to property owners.

“If you find it, it saves the building,” Earnest says.

Here’s a rundown of some important items to keep in mind when it comes to smoke testing.

A Negative Test Doesn’t Mean Results Are Conclusive

Sagging laterals can trap water, blocking and preventing the smoke from reaching roof leader connections or driveway drains. Debris collecting in stormwater basins or lodging in pipes also prohibits the passing of smoke. And although smoke testing can be done effectively year-round, weather can play a factor. Depending on the climate of your service area, smoke testing may not be an ideal diagnostic tool during the winter months. Frozen soil and snow cover impede the passage of smoke, masking pipe leaks.

Consistent Smoke Production and Good Airflow Output Are the Keys to a Successful Test

“Conducting a proper smoke test requires industrial blowers and consistent smoke production,” says Todd Patterson, operations manager for the Municipal Pipe Tool in Hudson, Iowa. “We’ve heard of contractors just tossing smoke bombs down a manhole and hoping for the best, or using a residential window fan to blow the smoke around. That’s just not going to do anything for the client.”

Typical smoke bombs last three minutes, but 60- and 30-second varieties are available. One possible solution is to use double-wick devices that tie together, increasing the smoke-generating time. Classic smoke candles generate a highly visible, uniform white smoke that travels farther and shows leaks that some systems may miss. The candles, with a total obscuring power 10 times greater than crude oil, fit most blowers, including those designed for liquid smoke. Liquid agents also generate dense smoke and can do so steadily for a longer period of time. Available in various sizes of containers, it is poured into a pressurized tank connected to the blowing machine. Operators may initially need extra time dialing in the blower to generate the optimum smoke.

Safety Concerns to Keep in Mind

With solid smoke-generating devices, fuse ignitions can be dangerous in the presence of volatile sewer gases, and the National Institute for Occupational Safety and Health requires workers to wear respirators in areas where smoke can be inhaled. The smoke contains high concentrations of zinc chloride, which attacks the respiratory system.

Liquid agents, because they do not require a fuse for ignition, appear safer. Still, contractors should obtain independent laboratory tests on the smoke being generated, not on the liquid as covered in Material Safety Data Sheets.

Be Sure to Notify the Fire Department Ahead of Time

It may seem like common sense, but it’s worth a reminder: Prior to a smoke test, inform local fire officials. 

“If the smoke comes out in the wrong place, it can set off the fire alarms,” Earnest says. “We let the fire department know that we’re doing this.”

Provide the Client Video of the Test Instead of Still Photographs

“Some clients expect to receive photographs of the testing, but I always tell them that shooting video is so much better,” Patterson says. “On a still photograph, you can barely make out a wisp of smoke, but on a video, you can actually see it moving. It’s the difference between night and day.”

Municipal Pipe Tool will also train the video camera on street addresses and nearby intersections to help clients pinpoint the location of the leaks.


Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.