I would not feel safe using this setup, because it just has so much more inherent risk designed into it than is necessary. Melissa, I think you are honestly over your head here. The fact that you originally built this setup and decided to later add a coalescing filter after you realized that you still smelled fumes proves this. If you truly knew what you were doing you would have known how poor of a setup this was/is. They make many different respirator cartridges for a reason.
I think the reason others are jumping on you is partly because your first post read more like a tutorial for others to copy and/or you wanting to show off what you did with a simple statement asking for our comments at the end. I don't honestly think you expected to get anything but praise for your setup, and that's the problem. I would not recommend anyone duplicate your setup for their own use at all. I look at your pictures and I don't even see a particularly well designed installation for compressed air let alone breathing. Bluntly, it looks to me like a system that was built according to random advice that was pieced together instead of being the result of truly knowing the theories and reasons behind effective overall design. For instance, why is there a spigot valve where you exit the air tank instead of a ball valve? Spigot valves reduce flow by their internal design. Your flex line from the tank to the wall has a low spot that will allow water to condense and puddle and then burp in the air lines. You also have a missing drip leg water drain right before your coalescing filter setup. That would take a lot of the moisture load (from condensation within the vertical plumbing before the filters) off the filters if it were there. Simple things like that tell us who are reading your posts (and looking at your pictures) that there are basic principals of a good basic installation missing. Coalescing filters also only remove liquid water from the system, water vapors often still remain and this will increase as the whole system warms up over time as it runs. That's why you often see expensive air dryers downstream from the coalescing filters in professional installations.
Good design eliminates the most wrenches possible from the mix from the very beginning so there is less to have to fix or account for later on in the system. There are poisonous chemicals that you can't even smell, etc. Your current system really has zero redundancy and zero steps taken to make the air entering the system as clean as possible to begin with. All the weight of keeping you safe and healthy is resting on the hope that a few filters will work ideally and that they will never leak, fail, etc. That's assuming they do enough to keep you safe even when working at their peak. Part of keeping them working properly is the "Moisture and temperature must be controlled" statement that ledhore made previously. For instance, if the temp of the air in the lines gets too hot the moisture won't condense out and get caught by the coalescing filters as it should. Also, if you decide to do a future oil change on the compressor and you use automotive 30w oil (with detergents in it) instead of non-detergent 30w compressor oil (like you should) the detergents in the oil can lessen the effectiveness of your filter at removing the oils from the system.
You are currently pulling your breathing air from the same air mass the fumes originate from which is unwise in my opinion. You are combining compressed air, moisture, heat, lubricants, and any combination of other chemical fumes into the same air mass and expecting to then filter it all out perfectly for you to be safe. Anything you do pull into the system will be sitting there and interacting with everything else in the storage tank (unfiltered) until the next time you decide to use the shop air.
If you are still going to go ahead with this, at the very least please flush out the whole storage tank, flush your lines, and let it all refill with completely fresh air before each time you use the mask. That will help increase the air quality in your hood and reduce the safety risk from whatever has been sitting in the tank and lines.
You would be 100x better off in my opinion if you just had your current hood fed from a brand new shop vac with a HEPA filter installed in it (often used anyways for catching sheetrock dust), with the intake air fed from the outdoors. A simple ball valve with a secondary bleeder valve installed on the ouptut would allow you to set the air flow through the hood ideally and also bleed off the excess to keep the load on the shop vac motor to a minimum so it runs as cool as possible. Many less variables, much lower chance of problems, and almost no chance of anything damaging your lungs that you wouldn't smell in advance (internal shop vac short, burning motor windings, etc). Yes the air will become warm using a shop vac, but I think you will find the air quite warm coming from the air compressor as well if it is ever run for any length of time. Air compressors get very hot as they run and it is really only the storage tank mass and the large initial plumbing size keeping the air temp down, but that benefit disappears as things run for a while.
