Key Considerations for Installing Centrifugal Air Compressors

By Rick Stasyshan and Ian MacLeod for the Compressed Air and Gas Institute

Compressed Air Best Practices® Magazine and the Compressed Air and Gas Institute have been cooperating on educating readers on the design, features, and benefits of centrifugal compressor systems. As part of this series, Compressed Air Best Practices® (CABP) Magazine recently caught up with Rick Stasyshan, Compressed Air and Gas Institute’s (CAGI) Technical Consultant, and Ian MacLeod of CAGI member company, Ingersoll Rand. During our discussion, we reviewed some of the things readers should consider when installing a centrifugal compressor system.

CABP: Having seen centrifugal compressors in several operations, I have to admit: many are quite impressive sites. Gentlemen, where is a good place to start when considering the installation of a centrifugal compressor system?

CAGI: The installation of any type of air compressor requires proper planning as well as adherence to the manufacturer’s recommended guidelines. Centrifugal air compressors are no different in that care must be taken during the installation process to ensure reliable, safe operation, and ease of maintenance. The manufacturer should always be consulted for specifics concerning the location and the application of the system. Proper planning and prep work will ensure a safe and efficient installation for maximum return on investment.

PLANNING A CENTRIFUGAL AIR COMPRESSOR INSTALLATION

CABP: What are some of the areas to be considered during this planning process?

CAGI: Before arrival of the new compressor, the end user or customer should convene a pre-installation meeting with the user site managers, site maintenance staff, the compressor manufacturer’s technical representative(s), and the contractors responsible for installation. Most compressor manufacturers have an installation checklist that can be — and should be — reviewed during the meeting. The goals of the meeting should include:

1. Clearly define scope of work, roles and responsibilities.
2. Identify any ship loose items and accessories that may require installation.
3. Review the manufacturer’s installation instructions.
4. Discuss site safety requirements, and address any questions or concerns.
5. Outline the timetable for completion.
6. CABP: From visiting plants with compressor systems, I know that the actual location of the equipment can impact system performance. What are your thoughts on this point — particularly concerning centrifugal compressor systems?

CAGI: You are spot on: choosing the right location is very important. While we would like to simply tuck the compressor in a corner and forget about it, the reality is proper location selection can assure the user of receiving maximum value from their system over its economic life. Obviously the location should be able to physically accommodate the compressor installation, but there are some other points to consider:

• Can the compressor be safely and efficiently maneuvered into place?  
• Is there adequate room between other pieces of equipment? 
• Are the required utilities (i.e. electricity and water) available nearby? 

We recommend referring to the manufacturer’s supplied drawings and rigging instructions prior to handling the compressor.

CABP: And what about future service and maintenance considerations?

CAGI: An excellent point. All compressors will require periodic inspection and maintenance. Adequate space needs to be provided for both routine maintenance and periodic overhauls. If permanent rigging is not in place, the location should allow for temporary rigging (such as forklift access) as required to perform maintenance.

Some of the components are heavy and awkward, and planning at the installation phase will ensure that compressors can be efficiently and safely serviced.

CABP: Do centrifugal compressors require “special foundations”?

CAGI: No they do not. However, while centrifugal compressors do not require special foundations, a level surface capable of supporting the weight is a must. The foundation should be free of any external sources of vibration created by nearby equipment. Many customers prefer to grout the compressor baseplate to ensure a level surface, although this is not always a requirement.

MAJOR CONSIDERATIONS FOR INLET AIR

CABP: In past discussions with users, room temperatures have been discussed. How does ambient temperature impact centrifugal compressor operation?

CAGI: The ambient environment can adversely impact a compressor system’s reliability, and centrifugal compressor systems are not an exception. We always suggest avoiding damp, dusty, or corrosive environments. If there is concern about a corrosive ambient, discuss options with the compressor sales engineer.

Solutions could include special filtration and/or alternative component materials of construction. A compressor sales engineer can also assist the user to ensure that adequate ventilation and ambient temperature in the room are controlled for optimum system performance.

CABP: I assume when you mention adequate ventilation, you are referring to inlet air. What are some of the considerations?

CAGI: Yes, once the location is determined and finalized, it is time to consider connection points. As mentioned, the quality of inlet air is important. Whether the inlet air source is within the compressor room or taken from outside, review the air quality to prevent potential problems. If air is coming from outside, look for warning signs, such as nearby cooling towers or exhaust vents. If the inlet air is taken from within the compressor room, confirm there is adequate make-up air coming into the room.

Inlet piping should be nonferrous material and contain a spool piece near the compressor inlet to facilitate inspection and maintenance. The inlet pipe must be sized to minimize pressure drop. The inlet pipe should be properly supported and not rely on the compressor for support.

Loose material, such as welding slag, can damage the compressor if ingested, and the inlet pipe should be inspected prior to start-up to ensure cleanliness. Refer to Figure 1 to see an example of properly installed inlet piping.