Check valves play a critical role in preventing reverse flow across a broad range of industrial piping systems. A specialized type known as the double door check valve provides enhanced backflow prevention through its unique dual closure design. Compared to single disc or swing checks, double door check valves offer superior flow dynamics, reliability, and backflow protection. Below we examine the operating principles, design features, benefits, and common applications of double door check valves.
Introducing the Double Door Check Valve
A double door check valve contains two closure disks or flappers mounted in series within the valve body. These dual flappers seal against angled seats on either side of a central piston. The flappers are spring-loaded and open fully during forward flow. If flow reverses, the flappers rapidly seal to stop any backflow. This dual sealing action provides tighter backflow prevention compared to single flap check valves. Double door designs also enable better flow characteristics with reduced turbulence and slamming.
Design Elements of Double Door Check Valves
Some of the key design elements of double door check valves include:
- Dual closure flappers for sequential sealing during reverse flow
- Central piston linked to flappers to enable full fluid passage when open
- Angled seating surfaces that flappers seal against in closed position
- Springs that keep flappers closed with pressure assist when reverse flow occurs
- Hinge pins enabling each closure flap to pivot and seal independently
- Non-slam operation due to progressive opening and closing of flappers
- Low pressure drop due to efficient, less turbulent forward flow
Double Door Check Valves Own Many Benefits
Double door check valves provide several notable benefits:
- Reliable backflow prevention with dual sequential sealing
- Higher backpressure capabilities compared to single flap checks
- Smooth opening and closing action with minimal water hammer
- Full flow area through valve body when open
- Reduced fouling and clogging due to enhanced self-flushing
- Suitable for vertical or horizontal installation
- Long service life with rugged, easy to maintain designs
- Temperature ratings up to 350°F for many applications
Typical Applications of Double Door Check Valves
Double door check valves have wide utility across industrial sectors. Typical applications include:
- Backflow prevention in pumping systems
- Protecting against reverse flow in chemical injection lines
- Installation on discharge of pumps handling corrosive fluids
- Isolating high pressure and low pressure circuits
- Stopping gravity or siphoned drainage flows
- Use in water treatment and purification systems
- Preventing cross-contamination in potable water lines
- Protection against sea water backflows in desalination plants
- Backflow prevention in fire suppression and sprinkler systems
With their superior backflow sealing capabilities, Wafer double door check valves deliver important protection across an array of critical piping systems. Considering their strengths in key applications leads to improved safety and operability.
Double Door Check Vavles Comparing To Lift Type
The main differences between lift check valves and double door check valves are:
- Design – China Lift check valves have a single door/flapper that pivots up to allow flow and down to block reverse flow. Double door check valves have two independently moving flapper doors.
- Flow Direction – Lift checks only allow flow in one direction, from the inlet to the outlet. Double door checks allow bidirectional flow, from inlet to outlet or vice versa.
- Closing Speed – Lift checks close slowly by gravity as fluid reverses. Double door checks seal tightly with both doors closing simultaneously for faster closing.
- Leakage – Lift checks are more prone to leakage over time as the single seal can wear. Double door checks have redundant seals for less leakage potential.
- Pressure Drop – Lift checks have a larger opening and thus lower pressure drop when fully open. Double door checks have higher pressure drops due to their smaller valve openings.
- Applications – Lift checks are used for simple one-way flow applications like water pipes. Double door checks are better for fluid transfer applications involving changes in flow direction like irrigation or pumping systems.