Liquid Relief Valves — Thermal & Overpressure Protection
Closed liquid systems—thermal expansion tanks, sealed water heaters, hydronic heating loops, and process equipment—require specialized relief valves to protect against dangerous overpressure from thermal expansion and pump deadheading. Aquatrol’s liquid relief valves deliver precise, gradual pressure relief for incompressible media, with ASME certification and full capacity documentation.
Why Aquatrol Liquid Valves
Liquids cannot compress like gas, so even small thermal expansion or pump deadhead can generate extreme pressure instantly. Unlike safety valves that snap open, liquid relief valves open gradually, modulating flow to prevent pressure spikes while keeping the system operating. Aquatrol’s pilot-operated designs provide smooth, stable relief performance across the full flow range.
Thermal expansion is the silent killer in closed systems. A sealed water heater heating from 60°F to 160°F can generate 100+ PSI of pressure—enough to rupture piping or fittings. Our relief valves are sized for your specific fluid volume, temperature rise, and system pressure, preventing catastrophic failure while maintaining system integrity.
Different liquids behave differently—water, glycol-based coolants, mineral oil, and food-grade products have varying viscosities and properties. Aquatrol sizes and selects valves specifically for your media, providing material compatibility, viscosity compensation, and pressure stability across seasonal temperature swings. Every valve includes engineering documentation proving protection.
| Series | Pressure Range | Cracking Pressure | Best For |
|---|---|---|---|
| 55 | 30–500 PSIG | 10–50 PSI | Thermal expansion tanks |
| 130 | 20–300 PSIG | 5–30 PSI | Sealed water heaters |
| 140 | 20–800 PSIG | 5–50 PSI | Hydronic systems |
| 560 | 30–1,000 PSIG | 10–100 PSI | Industrial process fluids |
| 560 | 20–500 PSIG | 5–25 PSI | Potable water systems |
Common Applications
- Thermal expansion relief in sealed water heaters
- Hydronic heating and cooling loop overpressure protection
- Pump deadhead protection in closed recirculation systems
- Industrial process liquid overpressure relief
- Food and beverage processing equipment protection
- Hydraulic system pilot drain and tank relief
- Sealed vacuum or pressurized equipment protection
Need Help Choosing the Right Valve?
Our valve engineers can help you select the perfect valve for your application.