This quick article is more like a review of the different compressors I’ve used and or rebuilt over the years. I’ll cover the Linear diaphragm, piston and rotary vane compressors.
I get questions like, “how long will they last” How much cost to run them and how noisy are they.
The big go to is usually the linear diaphragm since they are quite and less cost to run. Some are noisier than others, at least between the different brands out there. Some are rather cheap for the initial costs and some cost double that the cheaper ones. I’ve seen them last 9 years and other a month.
Ok let me try to explain the confusion and vagueness from the last paragraph. Linear diaphragms compressors are built to push a lot of air (CFM) but not much psi and best used on small shallow ponds 1/4 acre and less. Meaning the deeper you go with the diffuser and or tubing, the weight of the water adds back pressure to the compressor pushing the air. Another item adds to the back pressure which is the tubing that runs out the diffuser(s). using 3/8 tubing adds more back pressure to the compressor while the ½” 0r 5/8” allows more air to flow freely to the diffusers.
I’ve found that the linear diaphragms are only good to about 6’ of water depth on the diffusers. I did try one out on a 9’ deep pond and it lasted about a month. Have had customers who used a 3/8” tubing to the 5/8 tubing and the 3/8 added too much back pressure and the compressor failed. I also have one that lasted, I think 9 years before it needed rebuilt as the diaphragms tear over time.
The function of the compressor is a diaphragm on each end of the unit which moves back and forth between a generated field of magnetism as the pressure builds the stoke, or how far the diaphragms move back and forth are shortened pushing less air.
Piston compressors are about the same where some have lasted10 years and some needed rebuilt within a year. By the way all the manufacturers recommend rebuilding all types of compressors 12 to 18 months.
Heat is the first thing that comes into play with the piston compressors followed by pressure and maintenance of changing the air filter. Similar to a car engine there is a crank shaft that runs the piston up and down and small reed valves to pull air in and out to the diffusers. The seal or ring in the compressor is like a fiber cup which handles the heat from compressing air but over time will break down under heat and higher compression and of course normal wear. The only other issue I have run into is the capacitor had failed, but they are easily replaced and your back up and running.
Over all I like these type compressors the most, yes they make more noise than the linear as there is now question about the depth of water as most of them are rated to 30’ deep. Can be started and stopped with no worry about the depth like the linear.
When installing a system we usually have the compressor running and lower the diffuser in to be sure we can see where we are in the pond. On the Linear compressors it seems to work out well but you should turn off the compressor. It seems that once the system is off the linear has a hard time pushing air down the tubing and overcoming the water pressure. The piston compressor pushes through easily.
Rotary vane compressors provide more air (CFM) than either of the above options. I’ve not had a lot of experience with the other than one rebuild and one that the vanes had broke and jammed up. They are more expensive the other two and recommended to only depth of 12’ as they do not build a lot of pressure. /Best used in large shallow ponds.
As I said this is just a quick article to help explain the different compressors. Possible to add more to this down the road.