Deluge, Wet Pipe, Dry Pipe 175 PSI, and HP Dry 250 PSI Explained
These options describe how water is stored, released, and supervised in the sprinkler system. The right choice depends mainly on temperature conditions, hazard type, and how the sprinklers or nozzles are expected to operate.
What each option means
Deluge
A deluge system uses open nozzles or open sprinklers. When the release system operates, the valve opens and water flows immediately through all open outlets at once.
Choose it when:
- Rapid, full-area water application is needed
- The hazard is fast-spreading
- The design calls for spray nozzles or open sprinklers
Wet pipe
A wet pipe system keeps water in the sprinkler piping at all times. Water discharges only from sprinklers that open from heat.
Choose it when:
- The space is heated and will not freeze
- You want the simplest and most common sprinkler arrangement
- Fast response and low complexity are priorities
Dry pipe 175 PSI
A dry pipe system keeps air or nitrogen in the sprinkler piping instead of water. Water enters the piping only after a sprinkler opens and the dry valve trips. The 175 PSI option identifies the standard pressure rating for that system path.
Choose it when:
- The area can freeze
- You need sprinkler protection in unheated spaces
- Standard dry pressure rating is sufficient
Dry pipe high pressure 250 PSI
A high pressure dry pipe system works like a dry pipe system but is built for higher working pressure up to 250 PSI, depending on the configuration.
Choose it when:
- Your project requires higher pressure capability
- Hydraulic conditions or supply conditions exceed standard dry system limits
- The specification calls for a 250 PSI dry arrangement
How to decide quickly
- Heated building: choose wet pipe
- Cold or unheated area: choose dry pipe
- Higher pressure requirement: choose HP dry 250 PSI
- Open-nozzle or total-area discharge application: choose deluge