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Combustible Gas Indicator?

Post questions and info about combustion (flammable vapor) powered cannons here. This includes discussion about fuels, ratios, ignition systems, safety, and anything else relevant.
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Combustible Gas Indicator?

Unread postAuthor: BowerR64 » Wed Mar 26, 2014 10:53 pm

Is there any cheap sniffer thing we could mount to the top that would signal or show an LED when the gas is at its best mix?

There are a few "Combustible Gas Indicators" on e-bay but not sure if they measure what we use or not.
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Re: Combustible Gas Indicator?

Unread postAuthor: jackssmirkingrevenge » Thu Mar 27, 2014 4:56 am

Interesting thought.

You would need something that measures percentages, if it just detects the lower explosive limit then you will be firing a lean mix all the time. From my experience, a detector that can give you a reliable percentage reading would be prohibitively expensive to purchase and maintain.
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Re: Combustible Gas Indicator?

Unread postAuthor: BowerR64 » Thu Mar 27, 2014 5:16 am

Yeah they would need to hold up to the blast inside the chamber as well.

Once you fire up a fan then spray in the charge it would be cool to see a light to indicate if its ready, to rich to lean what ever.

Im thinking more for what i use as the calcium carbide builds as it reacts so mine isnt an instant mix. I think im pretty close to where i need to be but ive since switched to using rocks insted of the powder and it takes the rocks longer to react in the water.
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Re: Combustible Gas Indicator?

Unread postAuthor: jackssmirkingrevenge » Thu Mar 27, 2014 5:21 am

BowerR64 wrote:Yeah they would need to hold up to the blast inside the chamber as well.


Not necessarily, you could close it off with a ball valve. People do this in hybrids to protect their pressure gauges.

Once you fire up a fan then spray in the charge it would be cool to see a light to indicate if its ready, to rich to lean what ever.

Im thinking more for what i use as the calcium carbide builds as it reacts so mine isnt an instant mix. I think im pretty close to where i need to be but ive since switched to using rocks insted of the powder and it takes the rocks longer to react in the water.


I know I've said this before, but if you want a consistent mix, metering propane is the way to go ;)
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Re: Combustible Gas Indicator?

Unread postAuthor: POLAND_SPUD » Thu Mar 27, 2014 1:38 pm

we discussed it before

Most affordable sensors are way out of range (300ppm to 10,000ppm ) 0.03 - 1%
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Re: Combustible Gas Indicator?

Unread postAuthor: Technician1002 » Thu Mar 27, 2014 8:11 pm

The gas sensor used to detect Carbon Monoxide, Natural Gas, etc are generally based on the same semiconductor sensor. If you get the datasheet, you may be able to disassemble a Carbon Monoxide or natural gas sensor and interface it with an arduino, then with testing calibrate the resulting combination. The " expensive" sensors are simply temperature, humidity, compensated with linearaty corrections and calibrated for known concentrations of the target gas.

If you do your own calibration curves, you may be able to build a reasonable mix sensor.

Check with an RV dealer to locate a Propane Leak or Carbon Monoxide alarm.

http://www.adventurerv.net/safetalert-series-gas-alarm-black-detector-p-26244.html?osCsid=qbijl00bs1hjvcfjq1ei0d7in4&utm_campaign=partsfeed_ppc&utm_medium=cpc&utm_source=Froogle&gclid=CM64sJmHtL0CFVBffgodk1MAFA

Re calibrate one of those to "alarm" at proper mix instead of a lower level and you are done.
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