The engineering is inescapable: spark ignition is a lousy way to light a grill.
Millions of people use this technology to light the barbecue grills: a butane lighter. It works by the piezoelectric effect, applying pressure to a crystal of lead zirconium titanate to create a potential of several thousand volts, creating a spark. It’s low in cost, but spark ignition is a very poor way to ignite fuel air mixtures, especially when the mixture stoichiometry is uncontrolled, as in a gas grill. Better solutions are flame ignition or stratified charge, with the spark igniting a locally rich mixture and the resulting flame front lighting off the main vapour volume.
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Episode Transcript:
It’s late summer, and like millions of people worldwide, I use one of these regularly to light my propane grill. This is one of probably a half dozen that I own, courtesy of my local dollar store, and they all have one thing in common: they don’t work well.
Now, an impromptu straw poll of my friends and family confirms that whether you pay top dollar for these things, or buy them at a gas station or discount store, they don’t perform well.
And the reason has nothing to do with quality control, or Chinese production, or government safety regulations—it’s engineered into the product.
Here’s how these things work: inside the lighter is a piezoelectric material, a ceramic wafer made from lead zirconate titanate, usually abbreviated as PZT. It’s a ceramic perovskite for you materials guys, and was developed in 1952 at the Tokyo Institute of Technology.
Now, the piezoelectric effect has been known for 150 years, and it actually works in both directions, both producing a potential of up to several thousand volts when the material is compressed, but also demonstrating strain when a potential is applied across the material. A really practical use for this property is in the fuel injectors used in modern direct injection diesel engines, as well as in things like ultrasonic transducers.
So, if they work in these critical applications, why are they so lousy at starting my grill? Well, it turns out that inducing a spark to jump a gap is actually a very poor way to ignite any air fuel mixture. Automotive engineers discovered this in the 1970s when they attempted to ignite leaner air fuel mixtures to reduce emissions. Twin spark plugs were tried, but the only really effective solution was something called stratified charge.
Honda put this into production, calling it CVCC, and he used a brilliantly simple strategy: the spark plug ignited a relatively rich fuel mixture in a pre-combustion chamber, and the flame front from that fire ignited the weaker main charge.
It turns out that a flame is a far better way to ignite an air fuel mixture than a spark—which is why a match never fails to instantly light a grill when the spark lighter fails.
Is there anything you can do about it? There are a few things.
First of all, check the fuel level inside the lighter. It’s butane under pressure, and you should see a liquid level through the little window. The other thing you can do is to encourage the vaporization of that butane to create gas. Warming it in your hands helps.
And finally, remember that this is a spark ignition device, and anything that provides an alternate current path between the electrodes will weaken or kill the spark, so don’t leave the thing in the rain.
Or use this 200-year-old technology, the strike anywhere match. They always work.
