The $3 Gas-Saving Ring That Killed a Mother and Son

A Winter Night in Yulin: How a Gas-Saving Ring Bypassed Three Safety Locks

In November 2023, Mr. Lü, in Yulin, Shaanxi, was scrolling an e-commerce platform when he saw a gas stove flame concentrator ring. The page said, “Gas saving by half.” The picture showed flames gathered together. He later recalled thinking: It is not expensive, it works, and it saves gas. For daily life, over time, you have to think long-term.

The order screenshot stayed on his phone. A metal ring that cost a few yuan was installed on the gas stove in a rented single-story house. At the time, the older son was about to get married. The younger son was 16 and preparing for the high school entrance exam. Ms. Liu worked at a supermarket. Mr. Lü had worked at nearby construction sites. In the winter of 2023, he found a job as a transport escort and left home to work.

More than a month later, on December 24, 2023, it was a winter night.

A camera had been installed in the bedroom to watch the younger son study. In the footage, around 8 p.m., the boy studied for a while, then appeared to lose consciousness. Ms. Liu’s habit was to soak her feet before bed. That evening, she cooked a pot of meat and boiled a kettle of water. The kettle was on the left burner. The flame was low.

The next morning, December 25, the supermarket called Mr. Lü and said Ms. Liu had not come to work. Then the younger son’s teacher called and said the boy had not come to school. Mr. Lü asked the landlord to check. The landlord entered through the courtyard window. The window was shut tight. He pried it open with a screwdriver. Inside, the boy was lying on the bed, without breathing or pulse. The gas stove was still on. The flame was low. The kettle was on the left burner. The water had boiled dry. Ms. Liu was soaking her feet. Her head lay on the table. She was not breathing and had no pulse.

The police incident feedback that day said Ms. Liu and her younger son died of “natural gas poisoning; specific cause under further investigation.”

That same day, the local gas company inspected the house. Gas meter connections, gas pipe joints, and gas facilities showed no leaks. The pipes were fine.

Mr. Lü suspected the ring. After the deaths, relatives and the lawyer tested with a combustible gas detector. Without the flame concentrator ring, methane concentration did not reach the default alarm value within ten minutes. With the ring, it reached the default low alarm value in four minutes.

Four minutes.

A gas stove looks complicated, but it has four core parts: the nozzle, the burner, the primary air intake, and the secondary air intake. It uses atmospheric injection combustion.

Gas moves from a wider pipe into a narrow nozzle. Its speed increases. It enters the burner and travels to the burner cap. Near the nozzle, there is an opening connected to the outside air, usually called the air shutter. According to the Venturi effect, the fast-moving gas creates a low-pressure zone around it. Outside air is pushed in. Gas and air complete their first premix. This is primary air intake.

The primary air is not enough. It also must not be too much. Too much would cause flashback. So after the gas-air mixture leaves the burner cap, it still needs to draw oxygen from the surrounding air. This is secondary air intake. When both intakes work together, gas burns fully and becomes carbon dioxide and water, releasing heat.

The concentrator ring sits around the burner cap like a cover. It separates the flame from the surrounding air and blocks secondary air intake. With too little oxygen, methane does not burn fully. It produces carbon monoxide. Carbon monoxide has no color, no smell, and does not irritate the eyes or throat. When inhaled, it binds to hemoglobin and takes away the blood’s ability to carry oxygen. Mild exposure causes dizziness. It can also bring weakness and nausea. Severe exposure causes unconsciousness and death.

In a closed room, with long use of the gas stove and incomplete combustion caused by the ring, carbon monoxide concentration rises fast. The fire is still burning. The water is still heating. The food is still cooking. A person can lose consciousness without a strong smell and without an obvious flame problem.

The ring can disable three safety locks at the same time.

The first lock is the odorant that the gas company mixes into natural gas. If gas leaks, the sharp smell should warn people. But in the scenario caused by the ring, gas is not leaking into the air in large amounts. It is taking part in combustion. The odorant, as a combustible component, is likely consumed by the flame. The room does not have a strong smell. People do not smell it.

The second lock is the flame-failure safety device on the gas stove. Modern stoves usually have a flame sensing probe. If the flame goes out unexpectedly, it cuts off the gas automatically. But the ring causes incomplete combustion. The flame does not go out. It turns yellow, weak, and less efficient. The probe only knows “fire or no fire.” It does not know “burning quality.” The fire is still there. The safety device does not act.

The third lock is the gas alarm. If a home has a carbon monoxide alarm, or a combination gas alarm, it may detect the problem and sound. But many homes do not have one. Some only have a natural gas leak alarm, not a carbon monoxide alarm. Even if one is installed, it may fail because of a dead battery, wrong placement, or lack of calibration.

In the Yulin case, the gas company found no pipe leak. The detector alarmed four minutes after the ring was used. The pipes were fine. The accessory changed how the stove burned.

In April 2025, the Yuyang District People’s Court in Yulin issued a first-instance judgment. The court found that the cause of death was carbon monoxide released when the gas stove burned incompletely after the concentrator ring was installed. The manufacturer and seller bore certain compensation liability. The e-commerce platform bore joint and several liability.

On September 2, 2026, the second-instance judgment upheld the original ruling.

The lawyer, Ge Yuan, said the seller and manufacturer should bear more responsibility and that a further appeal may be filed. The ruling settled compensation. It did not settle why the product could be sold, why there is no mandatory standard, why the platform does not intercept it, or why it takes death for it to be seen.

Under current regulations, households are already prohibited from installing non-original gas accessories without authorization. The Regulations on the Administration of Urban Gas and the Code for Gas Engineering Projects state that household users should not install or modify gas facilities on their own, and should not add non-original accessories. In the household gas stove setting, the concentrator ring should not be used at all.

But “prohibited to use” does not mean “prohibited to sell.” Large numbers of products still circulate under names such as “outdoor windproof” or “commercial energy-saving.” Platforms cannot easily tell every buyer’s purpose. So a product that is dangerous in household settings can still enter thousands of homes through search, recommendation, and checkout.

A complete sales ban is one option. A more feasible path is a de facto ban in household consumer settings, plus precise governance in sales, platforms, standards, and recalls.

Mandatory standards and certification would bring concentrator-ring products into mandatory testing. They would have to meet limits on carbon monoxide. They would carry a prominent warning: “Do not use on indoor household gas stoves.”

Platforms should identify risks around keywords such as “concentrator ring,” “windproof cover,” and “energy-saving cover.” Products aimed at household users should be removed or carry forced warnings.

Market regulators should issue consumer warnings and establish recall mechanisms for products already sold.

Platforms cannot act only as information matchmakers. For known high-risk products, they should bear safety obligations.

More people need to know: saving gas is small. Life is big. A few-yuan “miracle tool” can cost something that cannot be recovered.

For ordinary families, the advice is concrete.

Remove any concentrator ring, windproof cover, or flame-gathering cover installed on a gas stove. Do not believe “gas saving by half.”

Install a carbon monoxide alarm. A natural gas leak alarm and a carbon monoxide alarm are not the same thing. Install a combination alarm, or install both separately.

Keep ventilation when using gas. Open a window or turn on an exhaust fan. Do not keep doors and windows shut tight.

Check regularly. Gas hoses, connections, and stoves should not be used beyond eight years. Replace them when they age.

Do not modify on your own. Gas stoves, gas pipes, and valves should stay as they were made. Any non-original accessory can change the combustion conditions.

The Yulin winter was cold. Mr. Lü once did not dare watch the camera footage. In the kitchen, the kettle on the left burner had boiled dry. The fire was still on. Ms. Liu was soaking her feet, her head on the table. The boy was on the bed, without breathing or pulse. Outside, the landlord pried the window open with a screwdriver.

A metal ring that cost a few yuan was installed on the stove. Four minutes later, the detector alarmed. One month later, two people did not wake up.

Take it off. Install an alarm. Open a window. Check the hose. Throw the metal ring in the trash. Leave a gap in the kitchen window. Keep the alarm’s green light on.