Gas Stove Safety Alert

My senior age father woke in the morning to an odd smell in the house. Looking around, he realized he had left the gas stove knob slightly open. Gas was flowing but the igniter had not activated to start the flame. Fortunately, the amount of leaked gas wasn’t enough to cause a serious problem.

We’ve also had this problem in our house. Speaking with friends, it was something that happens from time to time with gas stoves.

Gas stove knobs are designed with a safety feature and need to be pushed in before turning. Even with this feature, it’s possible to inadvertently bump a knob and slightly turn it on while working near the stove. The knob can turn about 10 degrees or so before the igniter turns on. In this position, natural gas leaks out.

Electric stoves have a light to indicate when the burner is on. This indicator light is required because the heating element can get very hot before it turns red. Gas stoves do not have an indicator to show the knob has been turned. It’s very surprising this feature hasn’t been added since the potential for an accident is very high.

A gas stove knob indicator would be useful to prevent catastrophic explosion or gas inhalation.

Supplies

3 volt LED https://www.amazon.com/Pieces-Clear-Light-Emitting...

2032 coin cell battery holder https://www.amazon.com/Shapenty-Plastic-Vertical-B...

2032 coin cell battery

Normally Closed, NC, reed switch https://www.amazon.com/gp/product/B088CQL44X/ref=p...

Wire 22 awg solid wire

Solder

3D printer and ABS material

Step 1: The Circuit and Sensor

A gas stove knob indicator design requires:

· Easy visual indication the knob has been turned

· Ability to calibrate the knob for different stove models

· Battery powered with service life of at least one year

· Knob design modifiable for different stove brands

· Aesthetically pleasing and professional appearance

The circuit needs to be small and contained within the knob.
A normally closed, NC, magnetically activated reed switch was used with a CR 2032 battery and 3 volt LED.

Other switches were tried, the NC reed switch was the most effective and conistent.

Step 2: The Knob

The stove knob design was made for a Whirlpool stove using SolidWorks. The STL file is included in this instructable. The design can be modified for other stove brands if the gas shaft has a different geometry.

The inside of the knob was hollowed out and a web design was used for strength. Pockets for the battery holder and sensor were included. The battery holder was positioned as far forward in the knob as possible to stay away from the heat of the stove. Coin batteries have a service temperature range up to 140 degrees F (60C). Measurements of existing stove knob temperatures during use did not exceed 120F (49C).

On the knob OD, lettering and symbols show the ignition (lite) and high through low flame positions.

A through hole was used for the LED to improve visibility.

Step 3: Knob Isometric 3D View

Step 4: Assembly

Once the circuit is assembled, insert it into the back of the knob. The LED should go on when there is no magnet near the reed switch.

Step 5: Install and Calibrate

Remove the existing stove knob, mount the magnet on the stove face near the 12:00 position. Install the knob.

The light will go off when the reed switch is near the magnet. Adjust the position of the magnet to calibrate. The LED should go on when the knob is rotated.

The NC reed switch is closed until it is near a magnet. A magnet is placed on the stove face behind the knob. The magnet is set near the reed switch in the knob closed position so the circuit is open. Adjusting the position of the magnet allows the knob to be calibrated.

The battery will power the LED for over 1,000 hours. This amount of time easily covers one years worth

of typical home use. The battery only powers the circuit when the knob is turned.

The magnet can be positioned so turning the knob even 1 degree will active the LED.

Step 6: Results