Gas Grill Igniter: Design Failure Therein

The Judges at the Trinity College Home Firefighting Robot contest use butane grill igniters to light the candles in the arenas, but the gadgets seem to have terrible reliability problems: very often, they simply don’t work. I brought a few deaders back to the Basement Laboratory this April and finally got around to tearing them apart.

It seems they don’t ignite because the trigger’s safety interlock mechanism shears the plastic gas hose against the fuel tank’s brass outlet tube:

Grill igniter with sheared gas tube
Grill igniter with sheared gas tube

I tried putting a small brass tube around the (shortened and re-seated) hose, but it turns out the trigger interlock slides into that space and depends on the hose bending out of the way:

Grill igniter with brass tubing
Grill igniter with brass tubing

So there’s no easy way to fix these things.

It seems to me that a device using flammable gas should not abrade its gas hose, but what do I know?

6 thoughts on “Gas Grill Igniter: Design Failure Therein

  1. Can the interlock be easily removed? If so, I’d remove it. Never understood the purpose of those anyway – AFAIK, interlocks are there to prevent ‘little fingers’ from using it. But I figure any kid that can push the trigger can also figure out how to slide the interlock in such a way that the trigger works. As I’m no longer a kid and *hate* interlocks and some other ‘safety’ features (e.g. the little covers in electric outlet boxes, to prevent kids from sticking things in the holes), I usually remove them. Saves me the aggravation every time I have to use the tool.

    Off-topic: A few weeks ago I too took apart an old igniter and modified it so two wires came out to do a bit of ESD testing of semiconductors. About 10 mm arc length, so I’m guessing at some 10 kV. Amazingly, common BC547 (universal NPN, bit like a 2N2222 or so) survive being zapped multiple times with one (after 2 or 3 dozen zaps I gave up), without changing its parameters. Haven’t yet tried it out on FETs or ICs, but expect they not to withstand such abuse as well – especially sensitive gates.

    1. Can the interlock be easily removed?

      Unfortunately, no… the interlock is an integral part of the valve pusher dingus: the same bar that opens the valve shears off the hose!

      I briefly thought of designing a new trigger, but quickly realized that way lies insanity.

      a bit of ESD testing of semiconductors

      Dance, you miserable junction, dance! Wheee!

    2. Shorten the existing brass nipple and install thicker walled tiny silicone tubing.

      1. It is just a material failure not a design flaw. Get better tubing.

        1. Uh, how is using the wrong material in a product not a design failure? [grin]

          Tell it to the manufacturer, if you can figure out who they might be: the name pasted on the outside probably has very little relation to the manufacturer-of-the-day.

      2. I could saw the end of the hose off, but it’s an integral part of the valve assembly: screw up and I get a shop full of butane. Worse, that part of the interlock actually slides nearly all the way along the brass part: the shearing happens early on, as it gets lined up for the big push, so a shorter brass tube doesn’t really help much.

        And, alas, my stash of tiny tubing came up empty for this one. I found some Tygon that slipped over the entire affair, but that’s not quite what’s needed.

        This one was mostly for curiosity. Now that I know what’s happening, I can rip next year’s set of lighters apart and determine if they’re going to fail the same way… not much help at the contest, though.

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