Help with gas detector placement 2

[grgjin]

I need to place some CO and MO gas detectors near one of our package boilers where there have been issues with leaky flanges on the exiting flue gas in the past. The problem is that the location is open to the rest of the boiler house. The roof is at least 10m tall and there is often a draft coming through the area. I'm not sure how accurate the detectors would be under those conditions. Should I use more than one detector per gas? What elevation should I place them at? Any advice will be greatly appreciated.

 

[Unotec]

Put them in the upper left corner

<<A good friend will bail you out of jail, but a true friend
will be sitting beside you saying ” Damn that was fun!” - Unknown>>

 

[JLSeagull]

Consider the likely leak places. Consider the prevailing winds and whether the components are lighter or heavier than air. Select locations downwind of the likely leaks. Consider areas above light components, below heavy components. Then add detectors to accommodate days with other winds. Then add detectors to accommodate circulation and eddies around equipment. Also, I suggetst that heavy components like H2S are found in light fluids like sour gas. Thus, consider detectors below light components and above heavy components. Throw in some open path detectors to be sure that you have it covered.

Where do I send the consulting invoice for providing this great help? :-D

 

[tickle]

What are you protecting? Personnel. If so I would want the detector where I might breath the gas in.

The CO is approximately the same density as air? Not sure what MO is (please excuse my ignorance). The flue gas is hot, so will rise. If it enters the roof space is this a problem? Do personnel access the roof space? If it gets into the roof space, can it escape to the outside of the building? Or is there a recirculation route.

I would consider placing them in regularly traficked dead areas and dead areas that may have personnel entering that area occassionally without the need for confined space entry. (by dead areas I mean areas where there is limited ventialation).

To determine the answer to your problem, you should really ask what are you trying to achieve? Why are you trying to achieve it? How do you know that you are getting CO and MO in the atmosphere? If you can answer these questions the location of the gas detectors would be obvious!

The other solution is to have some portable ones and do a study of where the gases accumulate. You can get ones with chart recorders (or even electronic gizmotry that monitor over a period of time).

 

[grgjin]

Thanks for your advice, tickle. It was a slip of the mind, I meant to type CO and SO2. And yes, personnel are the major concern. I believe both gases are lighter than air and would rise upwards, especially since they come from the hot flue gas.

The draft in the room has caused problems in the past with the portable detectors the workers carry. The alarms may go off for for less than a minute and then go silent again. This happened rarely enough that it was first believed to be nuisance alarms. I'm concerned this may occur with the stationary detectors as well, but from your advice I may need to place some extra detectors in these "dead areas." Thanks again for the tips.

 

[tickle]

I suggest that you go and have a look at the sensitivities of detectors to other gases.

I have previously had a look at the manufacturers data for permanently installed gas detectors and the findings were quite alarming. I cannot remember what the gases or contaminants were, but the outcome was that the sensor for the gas in question was significantly (1000 x) more sensitive to other contaminants. Therefore potentially the monitor would alarm for miniscule amounts of contaminants.