It was 250 years ago - in 1765 - the first reciprocating compressor built and considered cutting edge technology. In the intervening years, little has changed. Reciprocating compressors contain many moving parts and use a piston/cylinder to compress air, just like they did in 1765. They require a receiver tank for heat dissipation and the provision of consistent airflow. Since so little has changed, it is no surprise that today’s workers find many faults with the design of reciprocating compressors.
Some common complaints of reciprocating compressors include:
- The air pressure in the receiver tank must reach a certain level before any tools can be used. The tank must be constantly refilled, and under heavy loads the compressors cannot keep up with demand. This means constant stop-work intervals throughout the completion of a job.
- Reciprocating compressors are notoriously loud and have low frequency noise levels with decibel levels that may exceed the 90dB limit recommended for extended periods of time. This leads directly to damaged hearing – a major safety concern in mines, on construction sites, in train yards and on highways to name a few of the places these compressors are found.
- They are naturally prone to heavy vibrations, which are hard to dampen with most mounting systems.
- Reciprocating compressors tend to run VERY hot (more than 500F or 260C). They need extra space for cooling purposes. The air the pump out must be treated and cooled or you risk damaging your tools or downstream equipment requiring the air. The high heat also accelerates the breakdown of parts, increasing the need for frequent maintenance and parts replacement from normal usage. Oil also breaks down faster and requires more frequent changing.
- There’s another issue created by all this excess heat… Oil carryover. A common problem with reciprocating air compressors, and the older the compressor, the worse it becomes. Oil can be sucked past the piston rings into the air where it quickly turns into vapor from the excessively high operating temperatures. When the vapor cools, it can combine with water vapor to create harmful emulsions. The oil can also burn, forming fine carbon soot particles, which when cooled, becomes sludge.
Even with these many challenges, it took about 200 years after the first reciprocating compressors were used for rotary screw compressors to start making an impact. This trend started in the 1950s. Although originally patented in the late 1800’s, radical innovations in materials and technology have enabled the rotary screw compressor to leapfrog past their older predecessor. The advantages of the rotary screw compressor include:
- Extended lifecycles: 6,000-8,000 hours, and 20,000-30,000 with proper maintenance.
- Simple routine maintenance: They only require changing the oil, oil filter and air/oil separator about every 500 hours or every 6 months in mobile applications—dramatically reducing maintenance costs and service time.
- Rotary screw compressors generally do not require a receiver tank.
- They can run at full capacity all day, with no need for breaks or worries of overheating. To avoid breakdowns and overheating, Reciprocating compressors must be used at 60% duty cycle or below and given frequent breaks.
- Screw compressors also generally have lower discharge temperatures.
VMAC’s OEM group is here to help you with your air compressor needs. Whether you are looking for a total engineered solution or just need advice or knowledge, give us a call.
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