Skip Navigation LinksMetrix|Applications|Reciprocating Compressors

Reciprocating Compressors

Reciprocating compressors are unique pieces of equipment as they contain active components that are moving in rotary as well as linear directions. They also play a vital role in any process that they are employed in. Therefore, a reciprocating compressor’s health must be monitored doing more than just following the usual vibration monitoring rules.

The majority of applications for reciprocating compressors are in the oil and gas industries. Oil refineries use these compressors for processes that require high pressure delivery of essential gases. The natural gas industry also utilizes reciprocating compressors to transport gas via cross country pipelines. These compressors can also be found in chemical plants, refrigeration plants, or air compressors for tooling.

Transmitter Solutions


Download our Recip Monitoring Brochure



Why choose Metrix for monitoring your reciprocating compressors?

The answer is simple: better value.

1. Scalability
Metrix is the only provider to offer monitoring solutions easily scalable to the various sizes of reciprocating compressors, namely packaged/skid-mounted up to API 618 machines.  In contrast to their much larger API 618 counterparts, packaged recips are typically smaller in size, but can still occupy a prominent role in the plant. While a complex measurement suite and accompanying diagnostic software may not be appropriate, Metrix provides affordable and comprehensive solutions for this smaller – but no less important – class of machines. 
Metrix is now able to offer a focused solution for API 618 type recips including shutdown and alarm for frame vibration, impact severity, rod drop, and crosshead acceleration.  Large or small, Metrix truly delivers a scalable solution.

2. Simplicity
Our approach to reciprocating compressor monitoring is to simplify it without sacrificing effectiveness.  Accordingly, we have designed our offerings to use simple measurement concepts focused on the four key areas in which reciprocating compressors are most prone to mechanical problems. Metrix is the only company offering 4-20mA transmitter-based solutions. Our solutions focus on simplifying the user experience for installing, maintaining, and using the instrumentation, while delivering outstanding results and excellent value for the money.

3. Experience

Metrix monitors an estimated 3,000 reciprocating compressors around the world – more than any other provider.  Our solutions have been proven in-use for more than a decade and are purchased by OEMs and end-users alike.

4. Innovation
Metrix pioneered our patented impact measurement technology more than 10 years ago as a way for customers to reliably – yet simply – detect problems in running gear such as looseness in crosshead shoes, wrist pins, connecting rods/nuts, and other components. We also pioneered the first commercially available 4-20 mA seismic vibration transmitter.  Today, we continue to pioneer with the world’s first digital, programmable proximity system.  Our DATAWATCH IX monitoring system builds on this programmable theme by offering a flexible monitoring module – a 4 or 8-channel system programmable for virtually any vibration or position transmitter measurement.



Transmitter Solution
• Simple
• Cost-effective
• Takes advantage of existing control systems, PLCs or SCADA systems



Impact Monitoring
The impact measurement was originally developed as a reliable means of protecting reciprocating compressors. Mechanical conditions such as loose rod nuts, loose bolts, excessive slipper clearance, worn pins and liquid in the process are routinely detected on recips using the impact measurement.

The IT681X Impact Transmitter outputs a current level based on the registered number of events above a user-set threshold level that occurred within a configurable time window. Metrix calls this a measurement of “impact severity.” An output of 4mA indicates no events occurred over the threshold level within the time window. An output of 6mA indicates 2 events, 8mA indicates 4 events, etc., up to 20mA for 16 events. If set up correctly, the events equal the number of impacts due to looseness.

Valve Temperature
Valve temperature is a proven method for detecting valve problems.  Broken valves are a common mode of failure for reciprocating compressors according to industry studies. Metrix offers the ability to monitor valve temperature using DATAWATCH IX with RTD/TC input to the monitor.

Rod Drop
An indicator used to determine rider band wear is rod drop.  Using a proximity probe to trend band wear helps to avoid piston to cylinder liner contact and associated downtime for unexpected repairs.  A rod drop measurement provides the user the average position or an instantaneous position of the piston.  Alert and danger levels can be programmed with DATAWATCH IX or your PLC allowing maintenance to be anticipated and scheduled.

Frame Vibration

Frame vibration measurements are useful for monitoring vibration related to the running speed and forces acting on the machine.  Used in conjunction with an impact transmitter or an accelerometer, malfunctions associated with low frequency and high frequency events can be reliably detected.  Metrix recommends the use of the ST5484E Velocity Transmitter for frame vibration.