The toilet paper traps are available individually, as are the oil trap and regulator. You don't need another complete assembly if only one of them fails.
At any given temperature, air is much like a sponge. It can hold a lot of water in tiny invisible droplets. When the sponge is full, any reduction in temperature, or you squeezing the sponge, will cause droplets to form on it's surface and gravity will cause them to fall. Heat the air and it can hold more, but as it's cooled again, the air cannot hold as much and again the droplets will form and fall, because at that pressure and temperature the air cannot hold as much moisture. The point at which this happens is called the "Dew Point". If the air is warmer that the dew point, or the air is drier (lower relative humidity) the moisture will remain in the air and not form droplets and fall. So if the dew point is higher than the air temperature, no water droplets will fall out of the air.
Lower the air temperature with the same amount of moisture in the air and the dew point will rise. When it reaches 100% dew point the moisture in the air will begin to come out, forming water droplets on anything cooler than the air. In the Summer the air can hold a lot of moisture. As the Sun sets and the air cools, the dew point rises. At 100% dew point, your metal outdoor furniture (and tools) will have this moisture form in little droplets all over them. If the temperature of the air outside falls considerably, clouds may form and a small rain storm may occur. It's this temperature/humidity relationship (dewpoint) that we must learn to deal with, both to keep our tools from rusting and to keep moisture out of our air lines.
Getting most of the water to condense out of the hot compressed air by cooling the compressed air, ideally before it reaches the tank (in between the compressor outlet and tank inlet), will greatly reduce the amount of water getting into the air lines. Your tank outlet to your air lines should also be located about half way up the side of your tank. Warm air rises, so it's cooler and drier at tank center. Condensed water droplets fall to the bottom of the tank when the air in the tank cools, or is cooler, so you can drain them off from the bottom of the tank.
I installed a large transmission oil cooler, positioned where the air compressor fan pulley will pull air through it. The compressor outlet is connected to the top of this oil cooler and the bottom of it is connected to the tank inlet (where the compressor once connected). The hot humid air from the compressor is cooled when going through this transmission cooler, so the water in the air condenses into droplets and they enter the tank at close to the environmental air temperature around you. The condensed water droplets then fall to the bottom of the tank. If you have uncondensed moisture in your air lines, the compressed air is entering your air lines when it's still hot, and it's condensing it's moisture in the cooler air lines and then getting into your air tools and spray guns. It's best to stop it before it ever gets there.
My condensate drain is connected to a small tank made from a 1' length of 3" galv. steel pipe and two 3/4-3" adapter fittings located horizontally below my compressor tank. The outlet of this is connected through a 3/4" ball valve to 3/4" gav steel piping routed out through the wall of my compressor shed and then downward a few inches. I can open the ball valve whenever convenient and the air pressure drains the collected condensate out of the 3" pipe easily. When using my shop every day, I tend to do this every few days in the warmer months. Less when in the colder months. With this 3" pipe reservoir, no condensate remains in my tank to heavily rust it's interior. It always collects in this 3" pipe reservoir.
I have one of those toilet paper filters with air line fittings both in and out, so I can add and remove it easily from my air system. I usually put it in the line whenever sand blasting or spray painting, but haven't used it for much else in years. I live in humid North Carolina, but have no air line water problems since modifying my air compressor system with the transmission cooler and condensate collection method, and I draw my compressed air off the middle of my 80 gallon vertical tank, as described above.
I hope this helps you to keep your air dry at the point of use.
Charley
