What does dP1 Separator High mean on a Sullair compressor?
Short answer: Separator pressure differential high. If your Sullair Supervisor Controller is showing dP1 Separator High, the controller has logged a specific, documented condition. This page covers what it means, what causes it, what you can safely fix yourself, and when — and why — it takes a technician.
What exactly is the machine telling you?
Pressure drop across the separator is high on a flooded-screw machine, indicating plugged separator elements or a pressure sensor failure.
Which machines show this?
older large-frame Sullair rotary screw compressors — flooded-screw and two-stage industrial packages from the Supervisor era, many still running in plants today. The Supervisor reports by channel: temperatures are T1 through T5, pressures P1 through P4, and differential pressure dP1, so a fault reads like 'T2 Discharge High' or 'P1 Sump Pressure High' rather than a code number. Flooded screws warn at 225 °F on T1 and fault at 235 °F delayed or 255 °F immediate; sensor failures are flagged when a channel reads an impossible value. Practical tip: always record which channel number tripped — T-numbers and P-numbers map to specific probes on the machine, and that number is the first thing a Sullair technician will ask for.
What causes it?
- Separator elements plugged on the flooded-screw machine
- Pressure sensor failure mimicking a plugged separator
Can you fix it yourself?
The check is in-house — separator hours in the Maintenance menu and a locked-out look at sensor wiring. The element change is a distributor job.
Step by step — what to try, in order:
- Check separator service hours in the Maintenance menu
- Schedule separator element replacement
- Have sensor wiring visually checked with power locked out
When do you need a technician — and why?
The separator element sits inside the pressurized sump, so replacement belongs to your Sullair distributor's technician.
If it does come to a service call and you're in Nashville, TN or Birmingham, AL, we maintain independently compiled lists of local companies that service industrial air compressors — real businesses with verified contact information, none of whom paid to be listed.
Related questions
What does dP1 Separator High mean on a Sullair Supervisor Controller?
Separator pressure differential high. Pressure drop across the separator is high on a flooded-screw machine, indicating plugged separator elements or a pressure sensor failure.
Can I fix dP1 Separator High on a Sullair Supervisor Controller myself?
The check is in-house — separator hours in the Maintenance menu and a locked-out look at sensor wiring. The element change is a distributor job.
When does dP1 Separator High on a Sullair Supervisor Controller need a technician?
The separator element sits inside the pressurized sump, so replacement belongs to your Sullair distributor's technician. Call your Sullair distributor to replace the separator element.
Verified against service documentation: Sullair Supervisor Controller documentation for dP1 Separator High (best-aire.com)