Pressure drop is the difference between what your compressor produces and what actually reaches your tools. If your compressor shows 120 psi but your impact wrench only gets 90 psi, you have a pressure drop problem—and you're wasting energy trying to compensate.
The typical culprits are undersized piping, clogged filters, failing dryers, long runs with too many fittings, and leaking drain valves. Every component in the distribution system adds resistance. A well-designed system should have less than 10 psi total drop from compressor to tool.
Rotary Screw Troubleshooting
Pressure Drop – Rotary Screw Air Compressor Troubleshooting
Significant pressure loss between the compressor discharge and point of use, causing tools to underperform despite adequate compressor capacity.
Industrial systems
Field-tested diagnostics
Independent & unbiased
What this problem usually means
Check these first
5–10 minute checks before diving deeper
- Measure pressure at compressor discharge AND at point of use—what's the actual drop?
- Pressure drop across each inline filter—should be under 3 psi when clean
- Dryer differential pressure—refrigerated dryers should be under 5 psi
- Piping diameter vs. flow rate—is the main header sized for actual CFM demand?
- Count the fittings—excessive elbows, tees, and reducers add up quickly
- Condensate drain valves—stuck open drains leak air constantly
- Regulator settings at point of use—are they set correctly and functioning?
- Hose and FRL condition at tools—kinked hoses, clogged filters, stuck lubricators
Common root causes
Why this happens in rotary screw compressors
Undersized piping
Small diameter pipe creates high velocity and friction losses. Common when demand grows but piping isn't upgraded. Use pipe sizing charts based on CFM and distance.
Clogged inline filters
Particulate and coalescing filters accumulate contamination over time. Differential pressure gauges show when elements need replacement—typically at 8-10 psi drop.
Long runs with excessive fittings
Every elbow equals 3-5 feet of straight pipe in pressure drop. Long runs to remote equipment compound the problem. Consider a ring main or larger drops.
Dryer restrictions
Refrigerated dryers with fouled heat exchangers or desiccant dryers with saturated/damaged beds create significant flow resistance. Check inlet vs. outlet pressure.
Leaking drain valves
Automatic drains stuck open, manual drains left cracked, or failed float drains. Listen for hissing at drains when system is pressurized but idle.
What NOT to do
Don't compensate by increasing compressor discharge pressure—this wastes energy and doesn't fix the underlying restriction. Don't ignore "minor" pressure drops that add up across multiple components. Don't use quick-disconnect fittings for permanent distribution piping—they're a major restriction point.
Full Rotary Screw Troubleshooting Manual
Step-by-step diagnostics, root cause logic, and practical fixes for oil-injected rotary screw compressors. Save time and reduce downtime with proven methods.
- Step-by-step diagnostics for common failures
- Root cause analysis techniques
- Practical fixes with parts notes
- Works across all major brands