Many small companies ask “Do you have a used compressor?” when the customers old system fails, or needs to expand. We hear this all the time, and even I’ve asked this over my 50 years in the compressor business.
In the 1960’s and earlier, many double acting, cross head design, foundation mounted, air compressors were touted to last 40 to 50 years. That proved to be true, but technology moved ahead. In the 1970’s a rotary packaged machine was offered, requiring no foundation and less floor space. GUESS WHAT? Much lower price. At first it was 50 HP and over, then 25 HP and now as little as 3 HP rotary machines are available. That wasn’t all that happened. Computers were added to standard machines allowing automatic operation, sequencing, and programmable set ups. Machines require attendance and less mechanical work were performed by skilled, trained service technicians.
In the early days you could buy a rebuilt or used heavy duty air compressor. They were 5, 10 or 20 years old and expected to get substantially more years out of it. Compressor manufacturers factored into their sales expectations on the amount of parts that would be required over the life of the compressor- and this machine ate parts and parts sold at list price.
Now the rotary revolution came about and the machines require lubrication, separators, filters, hoses, and seals. Heavy air compressor manufacturers did not manufacture these items but purchased them. The dam was broken as anyone could purchase these items and use them to maintain the compressor. The lubricant was no longer oil, but various synthetic fluids that also were manufactured by outside companies. Therefore, the whole profit picture changed and many companies disappeared, and some only survive by name alone.
The Killer in used air compressors is technology. Rotary air end design has evolved to more efficient operation, and rotor sealing strips are no longer required. Motors have changed frame size; computer controls vastly expanded their capabilities and many in color, while variable speed machines are available, and many other small changes to make air compressors more efficient.
I am speaking about this because I saw an advertisement for used rotary screw air compressors which were rebuilt by a service company. This service company was using a name they had purchased from an out of business old air compressor manufacturer. They listed the actual age of these machines, and some were over 20 years old. What people forget is the purchasing cost of an air compressor is the least expensive part. In actuality, the electrical cost to operate is the most expensive part. Electrical and mechanical efficiency and control system schemes are what control costs.
My advice when buying an air compressor is to buy a new air compressor. Buy locally from people who will be there when you need them. Buy from a manufacturer’s authorized distributor. Stay away from assemblers who only have a low first price to offer. Remember! What are you going to do when the well runs dry? Sit and watch the Crawdads die? The same is true when thinking on your air compressor. Will the guy from the internet be there in your factory when it goes wrong? Low first price is not the answer.