PSI, CFM, and Nozzle Size Explained (In Plain English)
Blasting works because air moves abrasive media at high speed.
But three things control how well it works:
PSI
CFM
Nozzle size
Most people hear these terms and nod along without really understanding them.
Here’s what they actually mean, and why all three must work together…
What PSI Really Means
PSI stands for pounds per square inch.
It measures air pressure.
In blasting, PSI controls:
how hard the media hits the surface
how aggressive the blast is
how much damage can occur if pressure is too high
Higher PSI does not always mean better results.
Too much PSI can:
warp metal
damage softer materials
waste media
make surfaces too rough
Proper PSI depends on the surface and the media being used.
What CFM Really Means
CFM stands for cubic feet per minute.
It measures how much air volume the compressor can supply.
CFM controls:
how long you can blast without losing pressure
how stable the blast pattern is
how fast work can be completed
Think of PSI like speed and CFM like stamina.
You can have high PSI, but if you don’t have enough CFM, the pressure drops and the blast becomes weak and uneven.
Why CFM Is Often More Important Than PSI
Many blasting problems come from not enough air volume.
Low CFM causes:
pulsing blasts
inconsistent cleaning
slow progress
poor surface profile
That’s why professional setups focus heavily on compressor size. Steady airflow matters more than high pressure alone.
What Nozzle Size Does
The nozzle controls how much air and media can exit the hose.
Nozzle size affects:
air demand
blast width
cutting speed
media flow
A larger nozzle:
moves more air
cleans faster
requires more CFM
A smaller nozzle:
uses less air
allows smaller compressors
cleans more slowly
Nozzle size must match the compressor. If it doesn’t, performance drops fast.
How PSI, CFM, and Nozzle Size Work Together
These three must stay in balance.
If one is off, the whole system suffers.
Examples:
Large nozzle + small compressor = weak blast
High PSI + low CFM = pressure drops
Too much PSI + small parts = damage
Professionals choose:
the correct nozzle
the correct pressure
the correct airflow
They don’t guess. They match the setup to the job.
Common Blasting Mistakes
Many blasting issues come from setup errors, not skill.
Common mistakes include:
using too small a compressor
running PSI too high
choosing the wrong nozzle
trying to rush the job
Fixing these issues improves results immediately.
Frequently Asked Questions
Q: Is higher PSI always better for blasting?
A: No. Too much PSI can damage surfaces and waste media.
Q: Can a small compressor do blasting work?
A: Only for very small jobs with small nozzles. Larger work needs higher CFM.
Q: Why does my blast feel weak sometimes?
A: Usually because the compressor can’t supply enough air volume.
Q: Does nozzle size affect speed?
A: Yes. Larger nozzles clean faster but require more CFM.
Final Thought
Blasting isn’t just about pulling the trigger.
It’s about:
proper air supply
controlled pressure
matched equipment
When PSI, CFM, and nozzle size work together, blasting is fast, clean, and consistent.
When they don’t, problems show up fast.
Next up: Why “Dustless Blasting” Isn’t Actually Dustless.
