{"id":1132,"date":"2024-01-13T22:03:18","date_gmt":"2024-01-13T22:03:18","guid":{"rendered":"https:\/\/desiredcreations.com\/blog\/?page_id=1132"},"modified":"2026-03-16T18:22:27","modified_gmt":"2026-03-16T18:22:27","slug":"gas-safety-valves","status":"publish","type":"page","link":"https:\/\/desiredcreations.com\/blog\/my-okeefe-merritt-stove-restoration-intro\/gas-safety-valves\/","title":{"rendered":"Gas Safety Valves"},"content":{"rendered":"\n
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My Lucy sporting one of her two safety valves, a TS-11. This one gates the gas flow to the broiler. The oven has an identical system.<\/figcaption><\/figure>\n\n\n\n
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CP \u2013 The mark of approval put on any brand stove that has passed certain safety standards including having a gas safety system.<\/figcaption><\/figure>\n\n\n\n

Safety valves. It took me a little while to figure out how they worked, what their true purpose was.  But let\u2019s start with the outside of the stove. There\u2019s a \u201cCP\u201d logo. That stands for \u201cCertified Performance\u201d and is a trademark by the Gas Appliance Manufacturers Association<\/em> (GAMA) that ensures that your stove meets certain high standards, like the stove\u2019s oven\/broiler safety systems. My OKM vintage gas stove has safety valves and connected thermocouples for a safer operation of the oven and broiler.<\/p>\n\n\n\n

Robertshaw Gas Oven Safety Body & Magnet<\/strong>
Description<\/strong>
The Robertshaw TS Series thermomagnetic safety valves are control valves used to cut off the flow of gas to the burner in the event of a pilot outage. The magnet assembly is energized by voltage generated by a thermocouple that is heated by the pilot flame. When this flame is extinguished, the thermocouple voltage decreases until a spring overcomes the magnetic force and loses off both the pilot and main gas (the older valves just shut off the main burner gas). This control can be used for commercial and residential ovens, infrared heaters, chicken and pig brooders, recreational vehicle gas appliances and many more applications requiring automatic safety valves!<\/p><\/blockquote> <\/figure>\n\n\n\n

What it means is if, for any reason, the gas flow to the stove stops while the oven or broiler burners were on, in addition to the burners going out the pilot flame would go out. That would cool down the thermocouple probe which sits in the pilot flame. When the thermocouple is not hot enough, it signals the safety valve to close, which blocks gas from flowing to the burners.<\/p>\n\n\n\n

Seems silly. If the gas is off, why worry about gas to the burners?<\/p>\n\n\n\n

WHY!<\/h2>\n\n\n\n

Prior to safety systems existing, when these stoves were being produced, gas distribution was not always reliable. Sometimes, the gas supply would die out, shutting off the flames. Then after a little while, the gas would come back on.<\/p>\n\n\n\n

Unlike the cooktop burners, the oven burner is hidden. If say, a bread baker were only using the oven at that time the gas supply stopped then started again, she or he might not have realized what happened. It was possible the baker might open the oven to check,  realize the flame had gone out and try to relight the manually lit oven with a match.<\/p>\n\n\n\n

Without a safety system, the oven chamber could have filled up with a dangerous level of raw gas. Lighting an oven that was already full of raw gas\u2026<\/p>\n\n\n\n

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With a safety system, when the gas flow to the stove was re-established to the entire stove,  the safety valve would have prevented the raw gas from filling up the oven or broiler chambers because the valve closed when the pilot light went out.<\/p>\n\n\n\n

THAT WAS THEN. WHAT NOW?<\/h2>\n\n\n\n

These days, gas distribution is pretty reliable. Most often safety valves can seem to be a problem for three reasons: a) after the gas has been shut off from the stove (so the stove can be safely repaired or relocated), b) when the thermocouple bi-metal\u2019s charge dwindles and dies, c) when the safety valve loses its magnetic charge and cannot stay open.<\/p>\n\n\n\n

When my gas stove was moved into my kitchen, I needed to perform a manual reset of the two safety valves so I could test the oven and broiler. When the stove was disconnected from the previous owner\u2019s gas line, that killed the pilot flames which cooled the thermocouples which closed the safety valves.<\/p>\n\n\n\n

Each time I worked on my stove\u2019s major systems, I\u2019d shut off the gas to the stove. To restart the oven and broiler burners, I\u2019d have to manually reset the safety valves if I wanted the oven and broiler to auto light again.<\/p>\n\n\n\n

LIGHTING THE BURNERS<\/h2>\n\n\n\n
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Lighting instructions on an O\u2019Keefe & Merritt broiler door. They aren’t exactly clear.<\/p>\n\n\n\n

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Pilot burners<\/figcaption><\/figure>\n\n\n\n

The standard process I have gone through to reset a fully functional safety system:<\/p>\n\n\n\n

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  1. Made sure the pilot flame is on and the thermocouple probe is in that flame. The heat causes the thermocouple to charge and send a signal to the safety valve. The signal cannot open the safety valve, but it can only keep it open.<\/strong> If the pilot is not lit, I\u2019d light it and wait about a minute for it to warm up enough to signal the safety valve.<\/li>\n\n\n\n
  2. Propped open the cooktop lid to access the safety valve(s).<\/li>\n\n\n\n
  3. Turned on oven\/broiler gas.<\/li>\n\n\n\n
  4. Pushed and held in the red button on the safety valve. Pushing the button manually opens the safety valve, allowing the gas to flow to the oven\/broiler burner. Once the gas flow reached the burner, the pilot flame would ignite the oven burner. <\/li>\n\n\n\n
  5. Released the button on the safety valve. When everything worked properly, button would return to its original position, but the safety valve would stay open, because the thermocouple sent a signal for it to stay open. Big happy dance. <\/li>\n\n\n\n
  6. If the oven burner shut off after that process, my first hope was the thermocouple signal was too weak to keep the safety valve open. Time for a new thermocouple. Relatively speaking, an inexpensive and easy task. Or the safety was on the fritz. Major $$$ pout!<\/li>\n<\/ol>\n\n\n\n

    If you have a multimeter with a DC volt scale, you can use that to test your thermocouple\u2019s charge. When heated it generates a DC voltage of approximately 25 \u2013 30 millivolts.<\/p>\n\n\n\n

    VARIOUS SAFETY VALVE DESIGNS<\/h2>\n\n\n\n

    There are many different safety valve model for major gas appliances like stoves, water heaters and furnaces, but they all have the same purpose \u2013 to prevent unbridled raw or uncombusted gas. Their designs and features have evolved over the years. If you\u2019re trying to find a replacement safety valve for your stove, you don\u2019t have to necessarily get an original unit.<\/p>\n\n\n\n

    <\/p>\n\n\n\n

    But you do need to make sure the replacement valve meets all the critical requirements. For example, the gas line openings need to be the match the diameter of the gas lines in your stove, it needs to have correct port for the thermocouple, it needs to fit the opening of the previous unit, etc. There are workarounds for most of that, but it involves plumbing adapters, additional gas lines and\/or plumbers.<\/p>\n\n\n\n

    When my old gas furnace safety died, troubleshooting pointed to the safety valve as the trouble. I disconnected it and took it to a local appliance parts shop. Thankfully, the owner recognized my old no-longer-available furnace safety valve and knew which updated model would work.<\/p>\n\n\n\n

    Below are the safeties I’ve seen in the OKMs I’ve rescued.<\/p>\n\n\n\n

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    Lucy\u2019s TS-11, sitting inline between the broiler control and the burner. The body accepts 7\/16ths diameter gas line.<\/figcaption><\/figure>\n\n\n\n
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    Safety Valve TS-11 (head and body bolted together.<\/figcaption><\/figure>\n\n\n\n
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    Safety Valve TS-7 also known as the \u201cPickle\u201d<\/figcaption><\/figure>\n\n\n\n

    <\/p>\n\n\n\n

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    TS-7 or \u201cPickle\u201d exploded view<\/figcaption><\/figure>\n\n\n\n

    <\/p>\n\n\n\n

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    The Robertshaw\u00ae 1720 Series Thermomagnetic Safety Valve<\/figcaption><\/figure>\n\n\n\n

    <\/p>\n\n\n\n

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    Safety Valve General Controls MR-2<\/figcaption><\/figure>\n\n\n\n

    <\/p>\n\n\n\n

    There are a few more vintage safety valves posted on TOAC\u2019s<\/a> website.<\/p>\n\n\n\n

    Robertshaw Gas Valve 1720-801 Safety Series Gas Valve Head<\/a><\/h2>\n\n\n\n
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    The Robertshaw\u00ae 1720 Series Thermomagnetic Safety Valve is a control used to cut off the flow of gas to the burner in the event of a pilot outage. The magnet assembly is energized by voltage generated by a thermocouple that is heated by the pilot flame. When this flame is extinguished, the thermocouple voltage decreases until a spring overcomes the magnetic force and closes off both the pilot and main gas. This control can be used for commercial and residential ovens, infrared heaters, chicken and pig brooders, recreational vehicle gas appliances and many more applications requiring automatic safety valves.<\/p>\n\n\n\n

    Features and Benefits<\/p>\n\n\n\n