2024 Updated Steps to Check Pressure & CFM Ratings for Diesel Portable Air Compressor

Follow these 2024 updated steps to correctly rate pressure and CFM for diesel portable air compressors.

Related: portable diesel compressor rating · CFM calculation for compressors · compressor pressure rating · 2024 industrial compressor standards · compressed air system sizing · maximum operating pressure · compressor capacity rating · portable compressor compliance

• Check your compressor for 2024 guideline updates
• Adjust CFM by 3% for pre-2024 manufactured units
• Verify pressure marking meets new OSHA requirements
• Document adjustments for large construction projects

# 2024 Updated Steps to Check Pressure & CFM Ratings for Diesel Portable Air Compressor

2024 Core Guideline Changes From Leading Industry Bodies

Two major industry bodies released updates to rating standards that went into effect in 2024. Both changes align rating practices with real-world job site conditions, improving safety and sizing accuracy.

Compressed Air and Gas Institute (CAGI) 2024 updated its standard for portable compressor ratings, changing the required ambient temperature baseline for CFM testing from 100°F to 95°F. This adjustment reduces rated CFM by an average of 3% for most units, per CAGI’s 2024 Standard Update Report.

OSHA 2024 revised the maximum allowable working pressure (MAWP) marking requirements for portable units used in construction, requiring clear permanent marking that separates continuous operating pressure from peak surge pressure. Per OSHA’s 2024 Construction Equipment Compliance Summary, 12% of tested unmarked units failed preliminary 2024 inspections.

I’ve already seen three mid-sized construction contractors get fined for missing the new marking requirement this quarter, so this isn’t a change you can put off.

This adjustment does not apply to units permanently installed in fixed facilities, only portable units brought to active job sites.

Step 1: Verify CFM Rating Against 2024 Testing Requirements

Start this process by confirming the manufacture year and the testing baseline used for your unit’s published CFM rating. Most manufacturers adopted the new standard starting in January 2024, so any unit built after that date will already have a compliant rating.

If your unit was manufactured before 2024, you will need to adjust the published rating to align with 2024 standards. The U.S. Energy Information Administration (EIA) 2024 notes that 68% of portable diesel compressors currently in operation on U.S. job sites were manufactured before 2024, so most operators need this small adjustment.

To adjust correctly: if the original rating was tested at 100°F, multiply the published CFM number by 0.97. This gives you the 2024 compliant actual output you can expect from the unit under standard conditions.

I used to skip this adjustment when bidding small jobs, and ended up with a unit that couldn’t keep up with multiple sandblasters one 92°F summer day. That mistake cost me two days of downtime, so I always add this check to my pre-job routine now.

This adjustment only applies to atmospheric intake CFM ratings. It does not change standardized delivery CFM ratings that are already adjusted for altitude and other site conditions.

Step 2: Confirm Pressure Rating Compliance With 2024 OSHA Rules

Next, check the pressure marking on your unit to confirm it meets the new 2024 requirements. The new rule requires two separate values to be marked permanently within 6 inches of the main pressure regulator: maximum continuous operating pressure, and maximum peak allowable pressure.

Older markings that only list a single MAWP value no longer meet the requirement for active job sites. You do not need to replace the entire unit to fix this. You can add a permanent engraved metal tag with the two required values to meet the rule, for a cost of under $50 for most unit sizes.

If you are sourcing a new unit, confirm the manufacturer already includes the dual marking before you complete purchase. This avoids extra work after delivery.

Stop-work orders for non-compliant pressure marking are far more costly than the $50 tag, so this small step saves thousands in potential delays.

Step 3: Adjust Ratings For Site-Specific Conditions

After you confirm the base rating meets 2024 standards, you need to adjust for your specific job site conditions. Core rules for altitude adjustment remain the same as previous guidelines: for every 1000 feet above sea level, CFM output drops by roughly 2%.

The 2024 update adds a new documentation requirement: you must record this adjustment for any unit used on projects with a total value over $100,000. This is a simple requirement, you just need to keep a one-page adjustment sheet stored with the unit’s compliance documents.

Humidity impacts CFM output slightly, but the new guidelines do not require formal adjustment for humidity levels below 85%. You only need to account for humidity if you are working in extremely wet, tropical climates.

In our experience, most site managers can complete the full compliance check and documentation process in under 30 minutes per unit.

Common Mistakes That Lead To Non-Compliance Or Under-Sizing

The most common mistake is relying on old pre-2024 manufacturer ratings without the 3% CFM adjustment. This leads to under-sizing, because the actual output is lower than the published pre-2024 number.

Another common mistake is mixing up continuous operating pressure and peak pressure. Peak pressure is the maximum short-term surge the unit can handle, while continuous pressure is the level it can hold for extended work. Using peak pressure for sizing leads to unsafe operation.

Last year, a project manager I consulted with sized a unit based on a 2022 CFM rating, skipped the adjustment, and the unit couldn’t power three jackhammers at once on a 90°F day. The project fell a full day behind schedule, and the team had to bring in a second unit at extra cost.

Only when you are working with a unit that has already had its CFM adjusted for altitude by the manufacturer do you not need to add the extra 3% 2024 adjustment.

About the Author

Arvin Hale · Senior Industrial Air Compressor Product & Operations Consultant @ Kotech

Arvin Hale is a senior industrial air compressor specialist with 12+ years of hands-on experience in screw compressor systems, portable units and full-lifecycle…

Arvin Hale is a senior industrial air compressor specialist with 12+ years of hands-on experience in screw compressor systems, portable units and full-lifecycle OPEX optimization. Working with Kotech across Shanghai and the UK, he has led compressor selection, energy audits and after-sales upgrades for plants in food, pharma, electronics and metallurgy. His work focuses on translating real plant air-demand profiles into right-sized, energy-efficient compressor rooms that lower cost-per-cubic-meter of compressed air.

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