Ammonia (NH3) detection in industrial area

Hi everyone,

I am planning to make a compact portable construction based on Arduino, LCD screen and ammonia sensor (for examble MQ137) in order to detect ammonia leak in a big industrial room.

In this room there are pipes and machines that use ammonia and sometimes there is leak of ammonia due to various reasons. The result is that bad smell of ammonia that leads the factory stuff to try to find out where is the leak and repair it. So, I was thinking that if I make one compact portable box like the one I mentioned above, maybe it would be easier to find out where exactly is the leak. I'm thinking of this construction like this: to show on the LCD screen the ammonia presence or the concentration and if you move it near the leak, it would show that the concentration increases, so you will find that here is the leak.

However, I have worries if it would work. Mostly, I don't know if it would work like this, or if it will show just the same concentration in every place in the room. For example, if there is ammonia leak, I don't want to get inside the room with this construction and to show just that there is ammonia presence. I want this box to find out that in place A the ammonia presence is small, in place B is bigger, in place C the presence is too big, so the leak might be somewhere here.

Is it possible or will I waste my time to make it?

Thanks in advance

Those cheap sensors are not very specific, not very sensitive and are difficult to calibrate.

In cases where human safety is an issue, ammonia leak detection MUST be done with professional equipment.

This is required by law in at least some advanced countries. Excerpt from linked document:

The Occupational Safety and Health Administration (OSHA) Permissible Exposure Level (PEL) is 50 parts per million (ppm), 8-hour time-weighted average. Effects of inhalation of ammonia range from irritation to severe respiratory injuries, with possible fatality at higher concentrations. The National Institute of Occupational Safety and Health (NIOSH) has established an Immediately Dangerous to Life and Health (IDLH) level of 300 ppm for the purposes of respirator selection.

This is a safety critical application - buy the proper instrument and not rely on an Arduino .

OP is asking not about detecting whether there is ammonia, but finding out where it's from. Different application and not safety critical (that's what the regular ammonia alarms are for - or even noses, I don't know the allowed exposure limit vs. the minimum level to be able to smell this gas).

You know where the pipes are - what's wrong with using some soapy water to find the leak? By the time you can smell it, the leak should be big enough, and it's usually the place you last worked on.

Please don't get confused. It has nothing to do with safety. The hole area - room is equiped with proffesional sensors that alarm when ammonia leak is in critical levels, so my project has nothing to do with critical safety measures. However when the leak is very small (i.e. 5ppm) there is no danger but smell (ammonia has got HUGE smell even in extremely SMALL leaks). In this case the staff can not find out the leak because the can not use soapy water or something (the pipes are frozen due to the cooling system in which ammonia is used and the motors are hot). So the only thing they can do is smell with the nose to find out where this very small leak is. Usually it is a motor that needs to be off for maintenance, but is difficult to find which of the motors. So, here comes my project. Could it be done and work like I described? Move this construction in the area and see different ammonia concentrations? I don't care for accuracy.

The success of the project probably depends mostly on the sensor. It is likely that only you know whether the one you mentioned has the sensitivity and responsiveness that you desire (from reading the datasheet).

The parts for your project are not very expensive and it would be quite easy to assemble and program a prototype. Why not build one and see if it does the job? Do you have a good test environment?

It sounds like your project is a "sniffer".
So you would be best to put the sensor in a container and using a small pump, pump the air out of the container, a hole and pipe in the other end sucks in the air/ammonia, as you get close to the source the concentration should go up.

You need to look at what the gas companies use to sniff for gas in the street, but in a smaller hand held size.

Just a thought.. Tom.. :slight_smile:

(the pipes are frozen due to the cooling system in which ammonia is used and the motors are hot)

Have you thought about using a thermal camera? It might be able to "see" a small plume of cold gas escaping. It could also be used to look for poor insulation on the pipes and motors that are running hot. I would not be surprised if there is already one that you could borrow for a trial.

Thermal camera is way too expensive. I thought about arduino+sensor, because electronic component solution is much more cheap.
As for the test enviroment, yes I have got a test enviroment.

USD 26.54 still too expensive? It seems like this is exactly what you need. Gonna be hard to build your own for that cost - even if your time is free.

USD 26.54 still too expensive? It seems like this is exactly what you need. Gonna be hard to build your own for that cost - even if your time is free.

Although it calls itself a "leak detector" I don't think that device will do the job, it is more for detecting things like heat leaking from your home on a grand scale because of poor lof insulation etc.

I have found a video that shows a thermal camera detecting an ammonia leak. You see a whispy temperature distortion against the background, a digital readout is not going to let you "see" that;

For a really cheap option, providing you don't mind some flames and additional gasses in your workplace how about using a sulphur stick;

The Black & Decker device DOES NOT works in my case.
ardly, yes I know the sulphur sticks, however finding a solution is not the first thing here. My priority is to find out if the solution with Arduino+sensor+LCD works. If yes, then I will try and build it. If no, I will not build something. Sulphur stick solution or "human nose" solution are known already.

My priority is to find out if the solution with Arduino+sensor+LCD works. If yes, then I will try and build it.

It's cheap. Just do it and find out for yourself.

As a future refinement, for pinpointing a leak location, you could enclose the sensor in a box and use a small fan to draw air into the box through a hose with a rigid tube (wand) on the end.

Having worked with compact experiemtial ammonia refigeration systems for over 4 years now i can understand where the OP is comming from when trying to find ammonia leaks. Many of the off the shelf/personal/ portable ammonia detectiors are not very sensitive with extremely low ammonia values below 10-15ppm, and too slow to respond on the downslope of sensing. Having tried to use them to find leaks on a system were next to impossible, and i had to rely on the ol nose to find micro leaks.

Im assuming that you dont actually need a hard referenced PPM value.. Just a variance scale from lets say 0-10000 units. And using that variable range to detect, pinpoint and narrow down the leak location. Because ammonia is lighter then air and will rise, the leak will flow upwards and can be detected from above its location most of the time.

Just as a suggestion look for a "FC-22-I MQ-135" ammonia sensor "module" online. Supposedly it has a 0-5v output with an adjustable gain. You could tie that in with and arduino input and go from there.

Raptorex, which is the difference between MQ135 and MQ137? I see that the first one costs about 2-4 euros and the second 35-40 euros! It's kind of big difference in price.

thermal cameras are getting cheaper and cheaper,
i think the Quark is the camera from flir that plugs onto an iphone,
ask around and see if someone has one you can play with and see if the thermal camera works. if it does then a couple of hundred dollars isnt much for an industrial application right?

Does anybody know why MQ135 costs 3 euros/dollars and MQ137 costs 40 euros/dollars?

For mq 137 detecting concentration scope is 5-200ppm NH3 and for mq 135 it is 10-300ppm NH3.

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