I need some sort of a sensor that can tell me whether gases are flowing or not - inside 8mm tube 2

[shailisason]

Hi,

I need some sort of a sensor that can tell me whether gases are flowing inside 8mm tube
*gasas such as natural GAS/LPG/Oxygen/AIR
details:
I want to connect the sensor to my computer, and to get signal whether gases is flowing OR not flowing inside 8mm tube.
Ther is no "MUST" knowing the flow rate, Only If its flowing (there is air supply = ON) or not flowing(there is no air supply=OFF)
*NO water flow sensor (only if it works for gases aswell)
Im a student so If u can add Some details or any kind of guidance I Will be thankful!

*I added a sketch for your convenience

Thank you very much

 

[IRstuff]

Student posting is not allowed.

However, your question is not well thought out, as you've not defined the threshold flow. Are you wanting to detect a single molecule per hour flow rate?

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //

http://www.engineering.com/AskForum/aff/32.aspx

faq731-376 forum1529

 

[shailisason]

Hi, Im a student(openU) but I also work full time.
First, lets take natural gas as an example
All I want is to detect in real time if there is natural gas flow Inside the 8mm tube,so the signal ill get from the sensor will be "ON" while the natural gas is flowing, and while the natural gas is not flowing (the tube is empty) the signal ill get from the sensor will be "OFF".

I dont want to know whats the flow rate, just to know IF gases are flowing in the tube, or not flowing in the tube (ON/OFF)

I hope you understand me now.
thank you

 

[IRstuff]

I understood perfectly the first time. Again, what is your threshold requirement, i.e., what is the minimum flow that triggers an ON? Again, does one molecule of gas per hour constitute a "flow"? If not, then what does?

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //

http://www.engineering.com/AskForum/aff/32.aspx

faq731-376 forum1529

 

[shailisason]

my bad, apologies.
I dont have any backgound or knowlage in this isue so ill just elaborate why I need the sensor and for what I need it:
I hope you could help Thanks to your extensive knowledge.

I have a gas stove, the tube that connected to the gas stove is 8mm tube, on this tube I want to install a sensor (that can connect to computing device and transmit findings)

The finall result I want to get is as follwing:
1. when Im cooking on the gas stove I want the sensor to transmit "ON"
1.1 The sensor will transmit "ON" even If ther is no flame (for example: in case of gas leakage - my toddler "played" and opened the gas valve by mistake)

2. when the gas valve (in the stove) is closed (Im not cooking and there is no natural gas leackage- the gas valve is off)
so In this case I want the sensor to transmit "OFF".

About the threshold I really dont know what to say becase I just dont know, I hope that following my explanation you will be able to tell me what I need.(If you can post a link to the specific sensor I need It will be great!)

Im sorry for my bad grammer, and my bad expression - English is not my main language.

have a great week

 

[IRstuff]

Hobby posting isn't allowed here, either.

Now, you've said enough that you should be looking for a means of detecting that the valve is open

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //

http://www.engineering.com/AskForum/aff/32.aspx

faq731-376 forum1529

 

[shailisason]

I think you just dont understand me... where I said Its an hobby? (No one is born with knowledge - so I had to start somewher)
Its not about detecting when the valve is open..Its about detecting when air(or any gas form - not liquid) is flowing inside a tube or not flowing to the tube exit.. I just gave an example for you

Thank you anyway!

 

[IRstuff]

I understand what you think you want, but want you want requires a specification, and again, you have refused to specify that minimum detectable flow rate. And, leak detection does not require knowledge that anything is flowing, so buy yourself a leak detector:

http://www.homedepot.com/p/BrassCra...nd-Methane-Gas-Detection-BCGLD01-X6/202800802

"Hobby" on this site means "not work related."

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //

http://www.engineering.com/AskForum/aff/32.aspx

faq731-376 forum1529

 

[Compositepro]

Use a pressure switch located after the shut-off valve.

 

[shailisason]

Got you on that, Ill do my homework about the specifications I need and Ill post it here and Ill appreciate it very much if you will help me.

I didnt specify that minimum detectable flow rate becase I have no knowledge in isues like: how gases "acts" inside a tube when the gas blocked by some valve - Is still moving enough to be detected by the sensor? If yes - Is there a sensor that not enough sensitive to detect gas that blocked by a valve? to use flow sensor? to use ultrasonic sensor? I had so many questions due to my ignorance In this matter so I decided Its better to ask general questions so some one will direct me to what I need...

it is work related, never sayed its not,I tought its not relevant.

thank you again!

 

[IRstuff]

"it is work related, never sayed its not,I tought its not relevant."

re-read your original post; you never said it was for work:
"Im a student so If u can add Some details or any kind of guidance I Will be thankful! "

"Is still moving enough to be detected by the sensor? If yes - Is there a sensor that not enough sensitive to detect gas that blocked by a valve?"

Again, you're stuck on flow sensors. A standard leak detector simply attempts to measure the presence of a material that sufficiently exceeds its internal noise. A pressure sensor will only indicate a change in pressure, but if the tube is not closed off on the distal end, then there will be no change in pressure, but a leak detector will detect its target species, provided that its concentration is above its threshold. For the leak detector cited, its threshold is 1890 ppm, which would represent less than 0.2% change in pressure.

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //

http://www.engineering.com/AskForum/aff/32.aspx

faq731-376 forum1529

 

[shailisason]

I said Im a student In the openU (The Open University), its a university that allows you to to study after work (17:00+), via frontal lessons or recorded Video lessons , so there is no contradiction here.

Now Im saying its for work

Im not stuck on flow sensor, Im really open mineded, and thank you for the explanation.

ill fined what the minimum detectable flow rate(threshold requirement) and post it here hopefully you could help me then.

have a nice weekend

 

[itsmoked]

Really listen to what IR is saying. You don't want or need a flow-detection of any kind! You want detection of gas where it's not supposed to be.. Hence a gas detector is what you need and they're much easier to come by, are more meaningful for your application, (kid left the gas on, or gas is on and flame is out) and don't require you to put something "not safety approved" into your gas system.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[shailisason]

First I want to thank Compositepro for helping me.

TO "itsmoked"
You are wrong here... what I want is:

I want to know if the gas supply is On (meaning: the gas is flowing to the gas consumption product such as gas stove)
I also want to know if the gas is static Inside the tube (meaning: the gas is not flowing to the gas consuption product)

I want to be able to look on my computer screen and to see "ON" and "OFF"... thats why I need a sensor.
The example I gave with the "kid left gas on" was just 1 case among many.

buttom line: I dont need gas detector... I wannt to know whats happening inside the tube (flowing or not)
The tube is 8mm OR 5/16 inch
What kined of sensor do I need then?

thank you

 

[IRstuff]

Flowing - gas is present
not - no gas is present

Therefore, you need a gas detector. ANY decent gas detector will be way more sensitive than any flow detector you can get.

TTFN
I can do absolutely anything. I'm an expert!
homework forum: //

http://www.engineering.com/AskForum/aff/32.aspx

faq731-376 forum1529

 

[shailisason]

IRstuff

I think gas detector can tell me when the gas is present or not present in the air, and not inside the gas pipe.
I am wrong?
Gas is present in the pipe even when the gas is not flowing- the gas is preset but static.
Thats why my goal is to know "flowing or not flowing" and NOT "present or not present"
If flowing = there is use in the gas
If not flowing = no one is using the gas

Thank you

 

[Compositepro]

You guys keep talking past each other and not clarifying any points of confusion. I assume the OP wants to know if there is gas flowing to a burner or not. This is done all the time with a pressure switch located before the metering orifice in the burner. If there is pressure, there will be flow. If there is no pressure, there cannot be flow.

Google lpg pressure switch. They are made just for this purpose, for burner controls.

 

[shailisason]

Compositepro

Thank you very much! you are great

Can you please help alittle bit more and post here a link for "lpg pressure switch" that will fit 8mm tube (5/16)

Thank you again

 

[Compositepro]

You have to install a tee in the tube so that the pressure can be run through tubing to whatever pressure switch you select. This is pretty basic stuff, so you should probably get some local help with what you are unfamiliar with. Depending on where you are doing this there are regulations to follow for safety.

 

[shailisason]

Ok, thank you very much... you helped me a lot