Q:Why is cracking pressure important for a check valve?

Cracking pressure is a critical parameter in check valves because it determines the minimum upstream pressure required for the valve to begin opening and allow flow. By defining exactly when the valve starts operating, cracking pressure plays a key role in ensuring proper system design, reliable performance under low or fluctuating pressures, protection of equipment from backflow or pressure shock, and overall efficiency of fluid control systems.
1. Defines When the Valve Starts to Work
Cracking pressure is the minimum upstream pressure required to slightly open the valve and allow fluid to start flowing.
If the system pressure does not reach this value, the valve remains closed — meaning no flow.
2. Prevents Unwanted Backflow
A properly selected cracking pressure ensures the valve closes securely when pressure drops, preventing reverse flow that could cause:
• Pump damage
• Water hammer
• Contamination or mixing of fluids
• System shutdowns
3. Ensures System Efficiency
• If the cracking pressure is too high, pumps need to work harder, increasing energy consumption.
If too low, the valve may flutter (open and close repeatedly), causing wear and unstable flow.
4. Protects Sensitive Equipment
Correct cracking pressure helps maintain stable pressure zones, especially in:
• Chemical dosing systems
• Cooling/heating loops
• Boiler feedwater lines
• Air or gas compressor systems
5. Affects Valve Selection & Sizing
Different check valve types (spring-loaded, dual plate, swing, diaphragm, etc.) have different cracking pressures. Engineers use this value to:
• Match valve performance to pipeline conditions
• Avoid cavitation or vibration
• Ensure smooth startup and shutdown