Real-World Scenarios
Case studies from the field. Read the situation, decide what you would do, then reveal each step to compare your plan against a guided answer.
Sprinkler & supervisory · Advanced
Dry System Low Air Pressure on a Freezing Night
Read the full write-upSite
Unheated loading dock protected by a dry-pipe sprinkler system with an air compressor and a low-air supervisory switch. Outside temperature is 18 °F (−8 °C). After-hours call at 11 PM.
FACP · Panel display
SUPERVISORY: LOW AIR
DRY SYSTEM 3 · UNHEATED DOCK · 27 PSI
What you find on arrival
The panel shows SUPERVISORY — LOW AIR PRESSURE on Dry System 3. The gauge on the dry-pipe valve reads 27 psi; normal is 40 psi and the valve trips near 20 psi. The compressor is running, but pressure is falling about 1 psi every 10 minutes.
What do you do?
If the pressure keeps dropping, the dry valve will trip and flood the pipe in freezing weather. What do you do?