Optimal location for gas sensor ?

[Externet]

For the first time am moving to a house with gas service. Am afraid of it. All pipes have been checked for leaks by a professional. Still afraid, am installing a gas detector alarm.

Where is it better to install; near the ceiling or near the floor ? I believe it is natural gas; whatever that be... methane, propane, butane, hexane...

[Acme]

A quick search finds naught but hand-held portable gas leak detectors. I have a travel trailer that has a propane leak detector that is fixed and it is located a few inches off the floor.

 

If you find a unit simply follow the enclosed directions.

In a house with gas appliances, another important detector/alarm to have is a carbon monoxide detector. Mine mounts on the wall a few inches down from the ceiling.

[John Cuthber]

Natural gas is mainly methane and is lighter than air. It makes sense to put a sensor at ceiling level, rather than near the floor.

While you are up there, fit a smoke detector.

[fiveworlds]

Depending on the gas you get you may request to have a smell added. By Law here all gas must have a smell we add a chemical called mercaptan.

Edited September 25, 2015 by fiveworlds

[Externet]

Thanks.

The sensor ordered and to arrive soon, is :

----> http://www.ebay.com/itm/Plug-In-Combustible-Gas-Detector-Alarm-Sensor-Voice-Warning-and-Battery-Backup-/311164368273?hash=item4872d77591

 

There is other CO and smoke detectors already installed, but my paranoia is for the gas itself.

 

Will later modify to install/extend a buzzer and leds indicators to the upper level and the sensor itself in the basement, where all pipes are.

[studiot]

Having overfitted gas detectors, are you also fitting a radiation detector?

 

[Externet]

Perhaps one of these days the paranoia will expand to radon, to fit your question... meanwhile, will stick to combustion gas.

[studiot]

My comment had nothing to do with radon.

 

How do you think gas detectors work?

 

Meahwhile what do you think is the danger from gas supplies leaking gas?

[Externet]

Radiation ? On a gas related subject ? --> Radon.

 

Danger for leaks is Kaboom ! I do not think on how they work; am after an optimal location

[studiot]

Take a deep breath and Smile.

 

Gas detectors use radioactivity to perform the detection.

 

 

You like engineering so you should read this.

 

https://en.wikipedia.org/wiki/Flammability_limit

 

You are correct that the main danger is that of explosion since modern gas supplies are not poisonous.

 

However you since light gases are employed (supplied) an explosion requires a collection zone or they will disperse.

 

You should therefore place the detector(s) in likely collection zones at height where there is no outlet for these gases.

[Externet]

Thank you, studiot.

 

The americium pellet sensors are for smoke detection, as far as I knew. I do not think radioactivity is used to perform the detection for combustible gases.

Combustible gases use other sensing methods as infrared and catalytic, no radiation involved.

 

Some sensing modules look like : ----> https://duckduckgo.com/?q=combustible+gas+detector+sensor+module&t=canonical&iax=1&ia=images

 

A light description of a vendor product ----> http://smart-prototyping.com/MQ-9-carbon-monoxide,-combustible-gas-sensor-detection-alarm-module.html (There is also a .pdf data sheet in there)

 

And similar to the one I ordered ----> http://www.tech-faq.com/combustible-gas-detectors.html

Edited September 26, 2015 by Externet

[studiot]

I'm sure that there are many mehtods of monitoring combustible gases.

 

But how do you know that the gas you are 'monitoring' is what you think it is and not particulates/water vapour/something else entirely?

 

When I did my confined spaces training we covered a lot of explosion risks.

The importance of a confined space in the lead up to an explosion cannot be overstressed.

Fuel gases disperse too quickly in the open air to explode.

[John Cuthber]

 

 

But how do you know that the gas you are 'monitoring' is what you think it is and not particulates/water vapour/something else entirely?

 

 

It's called specificity and it's a vital part of the research the manufacturers do.

For example, one of the classic methods for detecting flammable gas is to heat a wire by passing a current through it. If there's a flammable gas present the gas reacts with air near the wire and heats it up more. That rise in temperature is measurable because the electrical resistance of the wire changes.

 

Water vapour doesn't burn, so it doesn't make the temperature go up.

[Strange]

Danger for leaks is Kaboom !

 

And how significant is that danger? Compared to something really dangerous like driving a car or crossing the road?

[studiot]

 

For example, one of the classic methods for detecting flammable gas is to heat a wire by passing a current through it

 

How long would the battery last in such a detector?

[Externet]

You were assuming it was radiation powered, now being battery operated.

Battery ? Probably not much; that may be why is AC powered...

 

 

And how significant is that danger? Compared to something really dangerous like driving a car or crossing the road?

A little less significant as the reason houses have mandatory smoke detectors ?

Only one house needed it among hundreds around.

Edited September 27, 2015 by Externet

[Sensei]

You were assuming it was radiation powered, now being battery operated.

Battery ? Probably not much; that may be why is AC powered...

It's not about power..

 

"An ionization smoke detector uses a radioisotope such as americium-241 to produce ionization in air; a difference due to smoke is detected and an alarm is generated. Ionization detectors are more sensitive to the flaming stage of fires than optical detectors, while optical detectors are more sensitive to fires in the early smouldering stage.[12]

https://en.wikipedia.org/wiki/Smoke_detector

 

That's interesting, looking at how they're designed, smoke detector could be source of spark to ignite flammable gas...

Edited September 27, 2015 by Sensei

[studiot]

Yes 'gas' explosions can be quite devastating.

Was the one in your picture a faulty appliance explosion or a collected gas explosion?

Do you know the % of each type?

 

The somewhat adversarial nature of this discussion is bringing out some valuable points.

 

That's quite a short lead.

 

Do you have sockets (wall*?* outlets) up near the ceiling in America?

 

Here is a (smoke I think) detector plugged into a normal pendant light fitting. The 'bulb' is then plugged into it.

 

[Sensei]

Very cool design. +1

It's seamless approach to solution how to mount and power it.

[John Cuthber]

 

That's interesting, looking at how they're designed, smoke detector could be source of spark to ignite flammable gas...

I can't see how the smoke detectors could do that; the current through them is of the order of pico amps or nano amps.

The flammable gas ones might but it's OK, that nice Mr Davy sorted that problem out in 1815.

https://en.wikipedia.org/wiki/Davy_lamp

[Externet]

...That's interesting, looking at how they're designed, smoke detector could be source of spark to ignite flammable gas...

 

...Very cool design. +1

It's seamless approach to solution how to mount and power it....

Cannot tell for smoke; but gas detectors use the Davy mesh pointed by John :

 

And if the pendant detector is battery powered and kept charged by AC, fine. But if powered by AC alone, is not that 'cool' to need the light on for it to work.

 

studiot :

The leak being from an appliance or other seems not determined at the article ----> http://www.dailymail.co.uk/news/article-2142801/Cheltenham-house-gas-explosion-Elderly-woman-Betty-Hodgkiss-miraculously-escapes.html

 

Not much remaining to perform an examination of cause. Perhaps a newer report gives clues.

Edited September 27, 2015 by Externet

[Externet]

Device arrived to my mailbox.

Instructions say to position near ceiling for 'natural' gas and near floor for LPG, whatever that be -liquified petroleum gas or liquified propane gas-.

Installed. Done.

Edited September 28, 2015 by Externet

[John Cuthber]

LPG is typically propane or butane- essentially a mixture, or whatever is cheap.