Img.1: Schematic graphic of check valve
Check valves are a simple cost-effective solution to protecting your circuit from backflow, also known as reversion. Each different design and configuration allow for the part to be a versatile component of the system design that can be manipulated to your specifications. Every different selection and combination will result in a different capability of the overall product. Advanced applications of check valves include specified cracking pressures, flow rates, and material compatibility.
Spring-Loaded Ball Check Valves are a time-tested product. Even upon the search of the schematic image for a check valve, it is a depiction of a spring-loaded ball in the symbol (ref. image 1).
This image also serves as a representation on how the check valve works to prevent backflow. In the “valve open” diagram, as the forward flow exceeds the amount of the cracking pressure, the ball is pushed back on the spring to allow the fluid to flow through. In the “valve closed” diagram, the flow has decreased to an amount below the cracking pressure, the spring extends to seal the closure back off. This is to show that as long as the flow is below the cracking pressure, the ball will stay in its blocking position.
Other Names for Check Valves
Check valves are called by many other names, for both general name as well as specified. Alternate names for check valves are:
General Names for “Check Valves”
- Non-return valves
- One-way valves
Application-Specific Names for “Check Valves”
- Reflux valves
- Holding valves
- Relief Valve
Technology-Types of “Check Valves”
- Spring-Loaded Ball
- Umbrella
- Duckbill
- Floating Disk/Diaphragm
- Poppet
Evaluation of Air Logic’s Spring-Loaded Ball Check Valve
Air Logic’s Spring-Loaded Ball Check Valve is capable of a max pressure force of 100 psi, or 8.6 bar. Our current designs have options of cracking pressure at 1 or 4 psi. It is due to the technical nature of the design of the Spring-Loaded Ball Check Valve that the valve is able to operate automatically to seal against the backflow. Since the spring allows for a trusted seal, the valve can be placed in any horizontal, vertical, or diagonal orientation to best conform to your design requirements.
Maneuverability
The Air Logic Spring-Loaded Ball Check Valves are easier to install and reposition in an assembly. The check valve’s purpose to keep the flows separated as long as the pressure does not crack the seal. Air Logic’s engineering of the spring-loaded design incorporates swivel fittings. The swivel fittings enable an additional degree of maneuverability to help protect the fluid circuit from tangled or blocked lines.
Tradeoffs
When evaluating which type of check valve technology is right for your application, consider these characteristics of a Spring-Loaded Ball Check Valve:
Sound Generation in Pneumatic Applications
Spring-Loaded Ball Check Valves may make audible noise in operation depending on the flow rate through the product and the specifications of the cracking pressure. This is due to the harmonic nature of a ball and spring combination generating oscillations during certain flow conditions. Generally, a low flow rate right at or near the cracking pressure is most likely to cause noise. This is not a concern in liquid applications, where the liquid will dampen the oscillations of the system, thus no noise is generated.
Stiction Between the Ball and O-Ring
When a ball and spring have been touching for a period of time, stiction may occur. This is observed as an increase in cracking pressure. It is due to the ball and O-ring having a slight adherence to each other. It can be affected by the inclusion or exclusion of lubricants in the fluid flow. Best practice on testing cracking pressures is to ignore the “first crack” by flowing through the check valve. Then, immediately repeat the cracking pressure test and take the reading from the “second crack”.
Range of Options
Air Logic currently markets 12 pre-designed options with different combinations of features to display the configurability of this exclusively made-to-order item. Of the pre-designed options, there is a choice of Silicon or Buna O-Rings; 1/4”, 1/8”, or 1/16” barbs; and 1psi or 4 psi cracking pressure. All of these choices are mixed and matched to create a wide array of possibilities to utilize within your designed unit.
That is only the start. The options go beyond the pre-designed 12 products Air Logic has listed. There are also the alternative O-Ring materials Viton (also called FKM) and EPDM; custom cracking pressures ranging anywhere between 1-10psi; and different barb port fittings (such as elbow’s and T’s). So, if you are not seeing the exact design you would need for your next project in our listed parts, always feel free to contact us to be connected with our expert team of engineers to configure the exact part you need!
Comments are closed