Air Dryers and Your Business: Frequently Asked Questions
We take a look at some frequently asked questions regarding air dryers and their usage - and why making a change might be the right decision for your business.
Air dryers have been used since, well, time immemorial on commercial trucks to help filter out water and oil vapour. But as time has marched on, so have advancements in technology that have served to highlight some of the factors that might cause an air dryer to malfunction. Here, we take a look at some frequently asked questions regarding air dryers and their usage - and why making a change might be the right decision for your business.
Why does oil get beyond the air dryer and into brake valves?
It's science. When the temperature of compressed air cools, the gaseous vapours revert to oil. These oil droplets may then go on to contaminate the air valves downstream of the dryer. Further complicating matters, most valves are lubricated by the manufacturer with specific lubricants that are designed to provide longevity to the valves. Compressor oil tends to wash away these lubricants, sending them through the air system where they pick up additional contaminants. In some cases, the lubricant washed out by the compressor oil is essential for the valve to function properly.
Finally, when the discharge temperature of the air compressor becomes too high, the lubricating oil breaks down into a vapour which then floats on the air stream and coats the desiccant pellets. There are a number of reasons why the temperatures would become excessive, including leaks within the air brake system, a malfunctioning governor valve and leakage from the purge valve due to oil contamination. Just like humans, being overworked like this will cause us to shut down. So perhaps it's time to give your air compressors (and yourself) a break by not making it work beyond its specific duty.
Why do the air tanks have water in them even with an air dryer installed?
Simply put: Over time, desiccant beads in the air dryer will become coated with carbon and oil, preventing the desiccant from absorbing water vapour and moisture. There are many other reason, too, such as the aforementioned high temperatures, leakage from the purge valve and the air compressor itself being too small for the vehicle it is installed in. Don't cause yourself problems that could easily be prevented - install the proper air dryer for the type of vehicle you are operating.
Why do air dryer purge valves constantly leak air?
Contaminated purge valves leak due to carbon and oil particles, preventing them from sealing properly.
Why must I frequently replace desiccant canisters?
The lifespan of desiccant is determined by the amount of contamination filtered from the air system. Desiccant canisters generally need to be replaced when large amounts of water are found in the air tanks.
Why does build-up to maximum air pressure take longer than usual?
The more the desiccant has been saturated with carbon and oil, the longer it takes to reach maximum air pressure. Additionally, a leaky purge valve and a blocked discharged compressor air line are other common causes.
Long story short? Overwork leads to underperformance!
What causes premature air compressor break down?
If you've been reading this entire post, you can probably already guess the answer to this one. An air dryer saturated with contamination causes restrictions, which ultimately leads to greater demand and workload for the compressor. This, as you can imagine, leads to a premature break down.
Let's review the reasons for air compressor failures in a handy bullet point list:
· Excessive discharge temperature
· Leaky purge valve
· Discharge volume of compressor too small for vehicle
· Discharge air line from compressor blocked by carbon/oil
What causes carbon build-up in the discharge line of air compressor?
High air temperature and pressure turns oil vapour into carbon deposits. The combination of carbon particles and oil droplets saturate the desiccant in the dryer, restricting its airflow. Basically, your discharge line needs an angioplasty.
How can an air dryer malfunction cause a vehicle breakdown?If working properly, the dryer should cycle on and off to exhaust impurities out of the system. However, carbon deposits in the purge valve of the dryer could cause it to continuously vent to the atmosphere. This, in turn, can cause air starvation to the brake system which will trigger the spring brakes. Once this happens, your vehicle is pretty much D.O.A.