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Difficulty: MediumPneumatic Tools and Compressors

A shop technician is selecting an air compressor to run a continuous-duty dual-action pneumatic sander rated at 8 CFM8\text{ CFM} at 90 psi90\text{ psi}. What is the most critical specification the compressor must deliver to prevent the sander from losing speed during sustained sanding operations?

  1. A
    A maximum receiver tank storage pressure exceeding 175 psi175\text{ psi}, regardless of pump delivery rate
  2. B
    An increased motor rotational speed operated on an ungrounded power circuit
  3. A continuous airflow delivery rating in CFM at 90 psi90\text{ psi} that meets or exceeds the tool's volume demandAnswer
  4. D
    Using heavy-weight automotive motor oil in the air line lubricator to seal internal motor clearances

Answer

A continuous airflow delivery rating in CFM at 90 psi90\text{ psi} that meets or exceeds the tool's volume demand
Continuous airflow delivery in CFM at 90 psi90\text{ psi} matching or exceeding tool demand is correct because continuous-duty pneumatic tools like sanders and grinders require a constant volume of air to maintain operational RPM under load. While PSI provides the necessary pressure threshold, CFM provides the volume flow that sustains operation.

Step-by-Step Solution

1
Identify the operating characteristics and air requirements of the pneumatic tool.
The dual-action sander is a continuous-use tool requiring an air volume of 8 CFM8\text{ CFM} at an operating pressure of 90 psi90\text{ psi}.
Continuous-run air tools consume a sustained volume of compressed air rather than intermittent short bursts.
2
Distinguish between air pressure (PSI) and air volume flow rate (CFM).
Pressure (PSI) provides the operating force, while flow volume (CFM) sustains continuous operation and motor speed.
If delivered CFM is lower than tool demand, the receiver tank pressure rapidly drops during use, causing the tool to bog down.
3
Select the compressor capability that ensures uninterrupted performance.
The compressor must deliver at least 8 CFM8\text{ CFM} at 90 psi90\text{ psi} continuously.
Matching or exceeding the CFM requirement at working pressure prevents starvation of the pneumatic motor under load.

Key Concept

Matching compressor CFM delivery at operating PSI to pneumatic tool consumption
Estimated Time:1m 0s
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Topics

Pneumatic Tools and Compressors

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