Propane & Natural Gas Leak Detection - Page 1
Forum section: electronics / general

author: adammunich
author_rank: Contributor
timestamp: May 20, 2020, 01:23:13 am
content: I did some experiments today with trying to detect propane using a 3.33um filter. This filter is selective for methane, which should be inside "natural gas" in detectable amounts. I've published my results so far on this page here:https://civilpedia.org/p/?pid=355&h=Seeing+Propane+Gas

author: Bill W
author_rank: Super Contributor
timestamp: May 20, 2020, 02:49:11 pm
content: Think about which parts of each molecule contribute to the absorption. You may be seeing the generic '-ane' C-H chemical bond rather than picking up methane in propane.There are freely available spectraMethane:https://webbook.nist.gov/cgi/cbook.cgi?ID=C74828&Type=IR-SPEC&Index=1#IR-SPECPropane:https://webbook.nist.gov/cgi/cbook.cgi?ID=C74986&Type=IR-SPEC&Index=1#IR-SPECPropane has a wider deeper absorption for the same area. The extra C-C broaden the spectrum making it less 'well tuned'.Bill

author: bap2703
author_rank: Regular Contributor
timestamp: May 20, 2020, 06:26:34 pm
content: If you use a static setup where almost nothing moves except the gas AND you have access to know frames without gas things can get easy : take your frame without gas and use it to "flat field" your video.But that won't solve your issue of methane and propane sharing absorption in your filter band.

author: helius
author_rank: Super Contributor
timestamp: May 20, 2020, 06:57:21 pm
content: Is it even possible to detect hydrocarbons using infrared imaging?I would have thought a spectrometer was required, if they have distinct Raman spectra (not familiar).

author: bap2703
author_rank: Regular Contributor
timestamp: May 21, 2020, 08:47:27 am
content: Yes it is, adammunich even gave you a nice video as an example.Some gases have absorption peaks that happen to be where the atmosphere doesn't. That's especially true for greenhouse gases. They are named like this because they block the infrared radiated by the earth at around 290K, that aren't by the normal atmosphere.That last sentence is equivalent to: we can see them with thermal cameras!However the challenge is the amount of radiation: thermal cameras work because they collect infrared light over a large bandwidth. But gases typically absorb* over a tiny set of peaks. That means if you want contrast between gas/no gas you want to reduce the camera spectral bandwidth to be narrow. It wont see much, but it will do so with good contrastA spectrometer typically does the opposite job, working with ultra narrow bandwidth to provide good spectral resolution: it needs a very sensitive sensor --> a way to achieve that is to use a single big "pixel".But there are also spectro-imaging instruments that are basically a camera-spectrometer. These are expensive and used for science and security (think army, satellites, airborne) - well Fraser might get one for $5 on ebay* Note that gases absorb IR light from a hotter object behind them, but if the object is colder you will see the emission from the gas itself.

author: Max Planck
author_rank: Regular Contributor
timestamp: May 21, 2020, 12:22:29 pm
content: QuoteThis is the source of your problem. You need a filter with a wider passband.Max

author: agiorgitis
author_rank: Regular Contributor
timestamp: May 21, 2020, 09:48:51 pm
content: Hey mate,Check out my thread here, about visualizing SF6 gas.https://www.eevblog.com/forum/thermal-imaging/sf6-filter-for-ir-camera/I didn't use a filter, but the gas was only visible when using High Sensitivity Mode of Thermal studio or Research IR, to process the video.On page 2 of my thread, I have uploaded some pictures (post 33) and a video (for which you'll have to rename to .wmv) at post 36Something which really helped me a lot, later on, was bap2703's advice:"The gas needs to be at a different temperature than what lies behind: you can try adding something colder or hotter in the background."Best solution is to use the sky as your background, which is around -50oC

author: EverydayMuffin
author_rank: Regular Contributor
timestamp: August 02, 2020, 04:10:00 pm
content: I recently came across the below sensors from Pyreos, they make thin film pyroelectric sensors and they look for perfect for this application.They have a dual channel sensor which is available with lots of different filters, including filters for Hydrocarbons (e.g. propane, butane, isobutane), SF6, Methane, CO2, NO and NO2.Datasheet:https://pyreos.com/pyreos-analog-to-sensor-two-channels-datasheetThey also have a dual channel sensor which is optimised for hydrocarbon gas detection applications.Datasheet:https://pyreos.com/pyreos-analog-to-sensor-for-hydrocarbons-two-channels-datasheet

author: Bill W
author_rank: Super Contributor
timestamp: August 02, 2020, 10:34:25 pm
content: Here is the next two levels up in system building with that kind of detector:https://www.sgxsensortech.com/sensor-selector/Lamp / detector for analogue sensing (eg IR11EM)Integrated micro for digital out (eg INIR-CD)Another bit of EEV / Marconi / e2v Chelmsford that got sold off (to themselves), but then they were sold again to Poland / ChinaBill

author: adammunich
author_rank: Contributor
timestamp: September 11, 2020, 11:39:21 pm
content: Wow, these sensors are very cool. I wonder if we could use them along with long range optics to detect methane leaks in an oil field. The "telescope" could be slowly scanned along the field, watching for unlit flares.

author: Klaus
author_rank: Contributor
timestamp: September 12, 2020, 07:10:38 pm
content: https://youtu.be/K9qDi8n5YZ8Some explanation and demo.