Suggestion how to monitor the level of propane/butane gas cylinder

Projects General Guidance
1

Hi folks,

I am trying to design a arduino project to monitor the level of my propane gas tank level, but i could not think in anyway to get a sensor that do this job.

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Does any body have a idea to monitor the level of this cylinders?

Cheers
--Adriano

2

By the weight of the tank.

3

great!

sorry about newbie question but may i user this sensor ? http://www.aliexpress.com/item/The-half-bridge-load-cell-internal-use-of-a-half-bridge-resistance-strain-gauge-range-50KG/619688200.html

Or do you suggest another one?

one tank p45 can reach 60kg when full.

thank you

4

That looks like a good place to start. There was no datasheet on that page about voltages or resolution, but this is not rocket science (yet).

I use pressure on compressed gasses, like air (dive tank) or CNG (cooking fuel for a boat).
I use weight on liquified gasses, like propane and butane.

5

Ok. I got it!

I realize that i need a load cell in order to measure the weight of my tank.

But the cost of good one may not be financially unfeasible to my home use :frowning:

thanks to everyone.

6

Load cells can be pretty cheap -- what kind of precision are you looking for? e.g., what is the smallest difference in weight that you want to measure?

7

I just want to turn on a led if the tank is close to be empty.

e.g.

full -> 60Kg / empty -> 38kg

if the weight of the tank is about 10% close to empty, something about 40kg, i'll turn on the led.

is pretty simple.

8

AdrianoOliveira:
I just want to turn on a led if the tank is close to be empty.

e.g.

full -> 60Kg / empty -> 38kg

if the weight of the tank is about 10% close to empty, something about 40kg, i'll turn on the led.

is pretty simple.

Well maybe just support the tank on a spring loaded board such that when the weight drops to your desired weight the board makes a switch contact that would generate the alarm signal you need?

Lefty

9

Thank you Leffy, the idea looks good!

10

i almost have my propane tank sketch done. im still waiting for china to send my parts. look thru my past posts and find the thread.
http://arduino.cc/forum/index.php/topic,152252.0.html

11

I think I'd go low tech with a limit switch. On my old gas grill the tank was set a little offset on an edge under the end of the grill with a little wire arm that stuck out the front (in an empty/full slot). A spring was attached to the top of the tank pulling it opposite to the natural full tank tilt to the offset side. As the tank empied the spring would gradually pull the tank back from the heavier offset side, moving the fuel indicater wire back toward the empty side of the slot it was in. The tall tank could be set on a piece of wood with a slightly offset ~ 1/8" dowel under it. The full heavy tank would slightly tilt to the offset side. Instead of a spring on the top of the tank pulling it in the opposite direction, an arm with a weight attached to the top of the tank could probably do the same. When the tank got empty the weighted arm would cause the tank to tilt to the weighted arm side, actuating a limit switch. teeter-totter tank.

12

zoomkat:
I think I'd go low tech with a limit switch. On my old gas grill the tank was set a little offset on an edge under the end of the grill with a little wire arm that stuck out the front (in an empty/full slot). A spring was attached to the top of the tank pulling it opposite to the natural full tank tilt to the offset side. As the tank empied the spring would gradually pull the tank back from the heavier offset side, moving the fuel indicater wire back toward the empty side of the slot it was in. The tall tank could be set on a piece of wood with a slightly offset ~ 1/8" dowel under it. The full heavy tank would slightly tilt to the offset side. Instead of a spring on the top of the tank pulling it in the opposite direction, an arm with a weight attached to the top of the tank could probably do the same. When the tank got empty the weighted arm would cause the tank to tilt to the weighted arm side, actuating a limit switch. teeter-totter tank.

but what if you are not home? go high tech dude.

13

I've re-purposed the load cells from cheap digital scales. The higher quality ones (like $39) have four of them to show you when you don't have your weight properly distributed. That's ten bucks per load cell, plus an LCD panel. Bargain. And you can adjust the range with a lever arm to get where you want to be.