Do not compare an air cleaner’s free-air movement directly with another product’s clean air delivery rate just because both numbers use CFM. The unit describes a volume per minute; the metric name tells you what that volume represents. Keep the full specification label beside each number before deciding whether the figures answer the same question.
Read the noun attached to the number
CFM stands for cubic feet per minute. Seeing the same unit on two specification sheets can make a numerical comparison feel straightforward. A shopper may put the larger number first and conclude that the ranking is settled. The missing step is checking whether the manufacturers are describing the same measured quantity.
Airflow describes air movement. Clean air delivery rate, or CADR, describes a particle-removal performance measure. AHAM’s portable air-cleaner performance FAQ explicitly distinguishes airflow from CADR even though both are measured in cubic feet per minute. The shared unit does not make the labels interchangeable.
A comparison note can lose this distinction before the shopper notices. Copying a bare CFM figure removes the wording that identifies the metric. By the time several products have been recorded, all the entries may look directly comparable, even though the source documents described different quantities. Preserve that wording when the note is first made.
Make the first line of your note the metric as written, followed by its value and unit. If the description says free air, retain those words. If it says CADR, retain that label and any particle category attached to it. This small discipline keeps a search across several tabs from collapsing different specifications into a single column called performance.
Use the rental listing’s actual free-air wording
A real example is Drying Equipment’s Beast 600 specification, which lists a variable-speed range of 250-600 CFM with the qualifier “Free Air.” Those words belong with the range. They should remain visible in a renter’s notes instead of being replaced with a homemade label such as 600 CADR.
The page’s current product name matters too. A saved link can contain an older model name in its address while the displayed listing describes a different product. Read the actual page and confirm the supplied unit. Do not assign an old model’s specification to a current product simply because its name remains in a familiar bookmark.
Suppose another sheet shows a particle CADR of 350 CFM. That invented teaching figure is not a competing rental specification. Comparing it with the listed 600 CFM free-air maximum does not establish that one product delivers more tested particle removal than the other. The figures have different labels, so the larger numeral alone cannot settle the proposed comparison.
A range also needs to remain a range. Copying only its upper endpoint loses information about how the specification was presented. Ask for the documentation relevant to the actual equipment and configuration when a particular performance question matters. Do not treat the maximum as a promise that every permitted arrangement will reproduce that number in the room.
Keep smoke, dust and pollen CADR labels intact
Where a product has documented CADR results, read the named category rather than selecting whichever number is largest. AHAM’s programme uses smoke, dust and pollen CADR information. A figure for one category should not be silently labelled as the result for another, or presented as a universal answer to every air-quality concern.
For example, if a product’s documentation provides separate smoke and pollen values, retain both labels when discussing the relevant concern. Do not average the numbers into a rating the source never published. A neat average can be less useful than the original values because it hides what was tested and replaces it with a calculation chosen by the shopper.
Check the supporting document for the exact model. A brand’s general explanation of CADR does not establish a rating for all its products. A mark shown in an unrelated advertisement does not automatically apply to the rental you are considering. Ask for the appropriate record when the comparison relies on a tested or certified figure.
Keep the particle-performance question within its scope. A particle CADR is not a general assurance about gases, every odour or whether a space is appropriate to occupy. If the concern requires professional assessment, the product comparison belongs within that advice. A numerical shopping exercise should not be turned into an independent clearance decision.
Leave an unavailable rating blank
If the information available for a proposed rental gives free-air movement but no supported CADR, write “CADR not established from this information.” That is a useful finding about your evidence. It is not the same as assigning a rating of zero, declaring the equipment ineffective or deciding that it necessarily has no relevant documentation elsewhere.
Ask the provider for the specific information needed. A request for the actual model’s documented particle CADR is clearer than asking whether the machine is powerful. If the provider has another appropriate way to specify equipment for the proposed task, obtain its explanation rather than forcing unlike figures into a consumer-product comparison.
Do not manufacture the missing rating by combining a headline filter-efficiency percentage with a free-air maximum. Those entries do not, by themselves, establish a tested CADR for the complete unit. Replacing an unknown with an impressive calculation can make the comparison look more rigorous while moving it further from the available evidence.
A good equipment discussion can continue with an honest blank. Preserve the labels you do have, request the evidence you need and let the intended task guide the next enquiry. The words beside 600 can matter more than the size of the number; removing them is the quickest way to compare two things the documents never said were equivalent.
