The Anatomy of Reciprocating Compressors
Air compressors are industrial workhorses that power pneumatic tools and machinery across manufacturing sectors. Several types of compressors are available to suit every application. This blog will explore one of the most-used compressor options with a deep dive into the anatomy of reciprocating air compressors.
What are Reciprocating Compressors?
Reciprocating compressors, sometimes called piston compressors, are positive displacement air compressors that provide high-pressure air. Reciprocating compressors use a piston to compress gas (air). They are best suited to applications that require intermittent air.
Reciprocating compressors contain just a few key components:
- The suction valve: Air is brought in through the suction valve in a vacuum created by the motion of the piston.
- The piston: The piston compresses the air by moving in a reciprocating, or back and forth, motion inside the cylinder, also called the air compression chamber.
- Air compression chamber: Air is compressed by the piston inside the cylinder.
- The discharge valve: This valve discharges compressed air into the air storage tank.
- The storage tank: Compressed air is stored here until there is demand.
The compressor operates in four steps:
Step 1: A rod and crankshaft move the piston back and forth in a “reciprocating” motion. Because the air is drawn in and then trapped in the cylinder, the motion of the piston compresses the air.
Step 2: The piston moves downward to create a vacuum within the cylinder, closing the discharge valve and drawing air into the cylinder through the intake valve.
Step 3: As the piston moves upward the intake valve closes and air is compressed, the discharge valve opens and releases the compressed air into the storage tank where it is cooled and delivered to the end point of use.
Step 4: The process repeats, providing a steady stream of compressed air from the storage tank.
The two most common types of reciprocating compressors: single-stage and two-stage. In a single-stage reciprocating compressor, air is compressed in a single stroke, while a two-stage reciprocating compressor, compresses the air to an intermediate pressure first and then to a higher pressure during the second stage for greater levels of efficiency.
Advantages and Disadvantages of Reciprocating Compressors
Reciprocating compressors have several advantages, but also a few disadvantages.
| PROS | CONS |
| Efficient in intermittent use applications | Most are not designed for continuous-use applications |
| Produce high pressures up to 30,000 psi | Duty cycle of about 50% means the compressor must cool down between cycles |
| Suitable for high-pressure, low-volume intermittent use | Subject to failure in continuous use applications |
| Available in oil-lubricated and oil-free models | Generate a lot of noise |
| Less expensive than many other types of air compressors | Often require overhaul or replacement sooner than rotary screw type compressors. |
Reciprocating vs. Rotary Screw Compressors
Reciprocating compressors have a lower upfront price than other technologies and are ideal for high-pressure, low-volume intermittent air needs. Comparing reciprocating compressors to rotary screw compressors, another common industrial compressor type, will help you select the best unit for your operation.
As a general rule of thumb, reciprocating compressors are recommended for applications with very low or occasional air demand and rotary screw compressors are usually specified when consistent air demand is essential to productivity or the compressor will run more than 50% of the time.
The table below compares other performance metrics:
| Performance Metric | Reciprocating Compressor | Rotary Screw Compressor |
| Duty Cycle | 20% to 50% duty cycle | 100% duty cycle |
| Flow Consistency | Intermittent flow | Continuous flow |
| Noise Level | Piston operation results in high noise level | Rotating screw operation is quieter for indoor installations |
Check out this blog for a detailed head-to-head comparison between reciprocating and rotary screw compressors.
Is a Reciprocating Compressor Right for Your Application?
Reciprocating compressors shine in applications where high-pressure, low-volume intermittent air flow is needed. Here, JHFOSTER experts answer your questions about specific applications.
Can I use a reciprocating compressor for spray painting?
Yes, they are ideal for high-pressure spray painting and industrial coating.
Are reciprocating compressors suitable for small pneumatic tools like nail guns?
Yes, reciprocating compressors are perfect for low-CFM intermittent shop work.
Why use a reciprocating compressor over a rotary screw compressor?
Reciprocating compressors are preferred in applications that demand high pressures and low, intermittent flow rates where rotary screw units don’t operate efficiently.
Routine Maintenance for Your Reciprocating Compressor
Every reciprocating compressor will come with an owner’s manual that addresses specific maintenance tasks and suggests intervals for routine maintenance, but you can expect to perform the following on a regular basis:
Oil Checks and Changes: Check oil level on a daily or weekly basis and top up if low. As a rule of thumb, the oil and oil filter (if equipped) should be changed every 3 months to prevent damage to the compressor. Your owner’s manual provides information on the recommended frequency for your unit, as well as the proper procedure and suggested oil type.
Inlet filter Care: To avoid inefficient operation caused by clogged filters, filters should be inspected weekly and cleaned or replaced as needed to maintain air quality and prevent pressure drop. Typically, inlet air filters should be changed at least twice a year or according to the manufacturer’s suggested interval.
Valve Inspection: Suction and discharge valves should be examined for wear and repaired as needed. Also check for restrictions to prevent overheating.
Prevent Moisture: If you have automatic drain valves, ensure they are in working order. Manually operated drain valves should be opened and drained daily to remove condensate. Eliminating moisture prevents damage-causing corrosion.
Troubleshooting Common Reciprocating Compressor Issues
Here are some common reciprocating compressor issues and how to troubleshoot them:
Overheating: If your discharge temperature is high, check for restricted intake or faulty valves.
Excessive vibration: Examine the unit for loose components or framing, which may cause excessive vibration.
Noise in cylinder: The piston operation of reciprocating compressors can generate a lot of noise. However, heavy knocking or high-pitched grinding or squealing sounds indicate potential mechanical issues, such as worn bearings or loose components.
Will not start: Check for power supply issues such as tripped circuit breakers or blown fuses, faulty pressure switches, stuck valves and low oil levels, all of which can prevent a compressor from starting.
Get Support from JHFOSTER Air Compression Experts
Reciprocating compressors are ideal for intermittent operations that require high pressures in low volumes. Your air compression partner, JHFOSTER can evaluate your application to determine if a reciprocating compressor is the right choice and can support you in troubleshooting and maintaining your existing compressor. Reach out today to ensure your air compressor is the most efficient one for the job.
