When working with pneumatic tools, a diesel air compressor is an essential part of the equation. Pneumatic tools are driven by compressed air, which is why it is important to ensure the compressor you select is right-sized. A diesel portable air compressor is practical for heavy-duty applications such as operating pneumatic tools and other construction equipment. When considering what size compressor to use, check the rated pressure — the pound-force per square inch gauge (psig) rating — of the air compressor to determine the right size for your specific needs.
Most of the pneumatic tools operate well at 90 psig. Pressure drop through the connecting hose size should be considered as well. With an expected 2-psig pressure loss in a 50-ft, 3/4-in. hose, a 10-psig pressure drop through a 250-ft hose may not allow a pneumatic hammer to work properly. Pneumatic tools require a volume of compressed air — or cubic feet per minute (cfm) — at the pressure known as psig. Cfm can help you determine the number of tools you can operate with the air compressor and how much power the air compressor can provide. Each air tool is designated a cfm requirement by the manufacturer to help ensure efficient and optimal operation.
To protect the compressor, only about 70 percent of its rated free air capacity should be used in gunite applications using tools such as pavement breakers, tampers, rock drills, chipping hammers and utility drills. Ensure your air compressor can adequately support demanding tools to minimize any possible downtime.
Pavement breakers are great for doing just that — breaking pavement. Typically, pavement breakers are available in light, medium and heavy models, ranging from 37 to 62 cfm. Light pavement breakers (37 to 49 cfm) are ideal for breaking light concrete, concrete bridge decks and general demolition work. Medium pavement breakers (48 cfm) are designed for concrete road breaking and other general demotion work. Heavy pavement breakers (62 cfm) are ideal for more rigorous demolition jobs such as breaking rough reinforced concrete.
Chipping hammers are a top choice for construction and light demolition work applications, including concrete and masonry removal and horizontal and overhead applications. Chipping hammers typically require 26 to 33 cfm.
Rivet busters are ideal for concrete and metal applications, such as removing rivets, heavy-duty chipping and concrete breaking. Applications may include bridge jobs, steel structure maintenance, railroad car repair, shipyards, petrochemical plants or other demolition work. Rivet busters typically require 44 to 50 cfm.
Demolition tools are available in light and medium models requiring 33.4 and 37 cfm, respectively. Light models are ideal for the excavation of clay and hardpan and light horizontal demolition work, while medium models are suitable for medium demolition applications such as concrete breaking and repairing bridge decks.
Backfill tampers give you all the power you need for compacting at a speed which allows comfortable control. Backfill tampers are the ideal tool for compacting backfill around utility poles, foundations and other structures. They quickly and efficiently compact backfill soil excavated to perform service line repair before patching the pavement. Backfill tampers require about 32 cfm.
Drilling hammers produce a pounding force to make them extremely efficient at setting anchors and blasting through masonry such as concrete and bricks. Drilling hammers require around 21 cfm to operate efficiently.
Rock drills are utilized for drilling and blowing and are available in several model sizes providing a range of downforce. With a range of cfm requirements — from 53 to 80 cfm for the light models to 123 cfm for the medium models — rock drills can satisfy numerous applications. For drilling depths of up to 6 ft and 1.5-in. diameter, a light drill is necessary, while drilling depths up to 10 ft and 1 3/4-in. diameter require a medium drill.
Sizing the Right Compressor
As mentioned, cfm is the primary factor to help you determine the number of tools supported by any given diesel portable air compressor. Due to the wide variety of applications, gun sizes, types of drive mechanisms and experiences of different nozzlemen, the compressed air requirements for gunite applications cannot be charted. Air flow requirements must be obtained from the manufacturer of the gunite equipment. Air pressure requirements are generally in the 55- to 85-psig range. To protect the compressor, only about 70 percent of its rated free air capacity should be used in gunite applications. For operation of several tools with one compressor, the following table provides the ratio of cfm times the number of tools:
For example, to operate eight heavy pavement breakers, which require 62 cfm for each tool, you would multiply 6.0 x 62 cfm = 372 cfm. Consequently, a 375 portable air compressor could handle eight breakers.