Spring-Based Check Valves are likely the most common type of check valve found in larger (i.e. not trigger-based) water blasters. They offer greater allowable flow than their Ball Bearing Check Valve counterparts while still remaining relatively cheap to manufacture and offering better flow control, allowing water (or air) to move one way while preventing backflow.
Parts of the Valve:
A spring-based check valve is comprised of a carefully shaped housing that surrounds a small, sculpted plunger (or plug) that is held against one side of the housing by a small spring. The key behind the design is the shape of the housing and plunger combined with minimal tension on the spring that allows water (or air) to flow around the plunger when the plunger is pushed open during forward flow while the spring seals the valve once there is not enough force in the forward flow to prevent backwards flow.
Water Blasters that Use This Valve:
Some blasters that use spring-based check valves include:
- Super Soaker 50
- Super Soaker 100
- Super Soaker CPS 1000
- Super Soaker Flash Flood - also used in the reservoir cap
- Water Warriors Blazer
- Water Warriors Vindicator
When there is no flow of water (or air) in any direction,the plunger is pushed snugly against the housing to prevent undesired backwards flow through the valve. Since it is spring-based, this valve remains properly sealed regardless of orientation and/or standard gravity. This makes the valve much more effective at preventing reverse flow.
When water (or air) is pushing in the direction denoted as forward, the valve will open once enough pressure to push against the spring is reached. The term, forward, is used strictly relative to the direction of flow through the valve since the actual position of the valve may have it facing upwards or even towards the back of the full water blaster. Due to the low tension spring used, it is easily pushed by moving water or air. Unlike ball bearing check valves that have a fixed cross-sectional opening, the amount a spring-based check valve csn open depends also on the force of the forward flow since more forward force would compress the spring farther, opening the valve more and allowing for greater flow through the valve.
Preventing Reverse Flow:
As noted above, thanks to the spring, this valve seals closed when there is no force pushing the plunger open. As such, when water or air attempts to flow backwards through the valve, pushing in the reverse direction serves only to push the plunger harder against the housing, tightening the seal further. Compared to ball bearing check valves, there is even less lag between the time the valve is open to when it is closed, thus doing a better job at keeping flow unidirectional.
As can be seen illustrated in the diagram above, there is no direct path for water (or air) to flow through the valve in the open state. Even when fully open, water (or air) may enter straight into the valve, it must then deflect to go around the plunger, pass the spring, then exit through the out port. As the plunger's head must be larger than the hole it seals, little can be done to improve flow lamination through this type of valve. Water (or air) must flow around the plunger.
Strengths and Limitations:
The spring-based check valve is a simple, effective way to create a unidirectional valve for controlling water (or air) flow through a system.
Being spring-based, this valve rests in its fully-closed position, preventing undesired reverse flow more effectively than ball bearing check valves. Moreover, since the plunger is plastic, the size of this type of check valve can be increased, yet remain effective even when scaled up. As the force required to open the valve is dependent on the strength of the spring used behind the plunger, even a larger plunger can be opened with reasonable force is desired. This allows larger versions of this valve to be used when one wishes to have larger tubing and greater flow through the system, but still maintaining unidirectionality. This is why these are the valves commonly found in larger water blasters since more water needs to be pushed and would exceed the capabilities of ball bearing check valves.
Interestingly, large versions of these spring-based check valves were used in the reservoir caps by some Super Soaker and Storm Gun water blaster models, being labeled as "Quick Fill Caps" for the Super Soaker brand models. The idea here is that the reservoir could be filled from a hose or other higher-pressure water source more quickly through the cap without needing to unscrew the cap. The wide-diameter spring and sealing mechanism worked to varying degrees, but functioned best when a hose's water pressure was of a good strength.