LPG Sensors with BCS

Discussion of the physical aspects
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el_hombre
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LPG Sensors with BCS

Post by el_hombre »

Would it be possible to use a LPG sensor like this type?

http://www.parallax.com/product/605-00009

I would like a way to have the BCS shut down and start an alarm if it detects a propane leak.
brahn
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Re: LPG Sensors with BCS

Post by brahn »

Probably not directly. This appears to work by varying the resistance based on the ppm of LPG. The only analog inputs on the BCS are temperature inputs which get run through the Steinhart–Hart equation to convert the resistance to temperature.

To use this with the BCS currently, you would need an intermediary (Arduino, Raspberry Pi, many other options) to read the resistance and determine whether it was over or under your threshold. The intermediary could then send a signal to a din on the BCS which could be used to stop any running processes.
el_hombre
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Re: LPG Sensors with BCS

Post by el_hombre »

get run through the Steinhart–Hart equation
I would like to think that name was intentional. :)

Seriously, thanks for the reply. Its what I suspected but wanted to get someone else's $.02.
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oakbarn
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Re: LPG Sensors with BCS

Post by oakbarn »

My own $0.02

When I looked at how this worked (downloaded the PDF), it looks like it has an input of 5 vdc for a heater, and a 5 vdc output signal for an alarm. I was thinking you could hook it up to DIN on the alarm. The amperage according to the diagram was milliamps so I thought it might work. On the other hand, I am not willing to test this with my BCS.
brahn
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Re: LPG Sensors with BCS

Post by brahn »

I was looking at the datasheet PDF, which only talks about variable resistance. That document appears to be for the sensor itself. I looked at the other PDF which seems to talk about the module Parallax builds around the sensor. It does look like this would work fine with the BCS once you get it calibrated. It says "The gas sensor module’s ALR pin should only be checked when the heater is on and the readings have stabilized." I'm not sure how long that takes or how that would work with the BCS on startup.
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