Tesla Valve

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Last updated Wed 13 Apr 2022

While many valves are 'active' valves, as they require an active component to either restrict or allow the flow of fluids, the Tesla Valve is a 'passive' valve that restricts fluids without the need of any additional components. Named after its inventor, Nikola Tesla, the Tesla Valve is an incredible feat of engineering, as it provides effective fluid resistance despite the lack of moving components.

Microfluidics

The Tesla Valve, referred to as a valvular conduit by Tesla himself, is best suited for microfluidics. While most pipes, valves, and other plumbing components are designed for macrofluidic applications, the Tesla Valve was built for the purposes of both macrofluidics and microfluidics instead.

Macrofluidics is a term applied to any fluid system large enough to allow volume forces to dominate all other forces. Conversely, microfluidics are dominated by surface forces instead. This phenomenon only occurs at extremely small scales, typically with channel sizes between 100 nanometers and 500 micrometers in diameter, at which stage the physics at play within the fluid system changes dramatically.

Microfluidics are applied practically in the creation of inkjet printer heads, micro-thermal technology, and DNA chips, amongst other applications. Some of these processes are active microfluidics, which rely on miniaturised active components to influence the fluid, though many of these processes are, instead, passive. For these purposes, a Tesla Valve provides an excellent, low-maintenance solution for fluid control.


The original patent for the valvular conduit.

The Design Of The Tesla Valve

The Tesla Valve is a simple creation that allows fluid to flow in one direction but not the other via a series of 'flow-control' segments. These segments are simply arched chambers that force fluid back onto itself if it is flowing from one direction, but allow the fluid to flow nearly unimpeded from the other. In his original patent, Tesla does specify that surface friction will act upon the fluid in the 'open' direction, but this force is largely negligible in most applications of the Tesla Valve.

One must note, however, that the Tesla Valve cannot actually stop the flow of fluid entirely. In its closed state, Tesla notes that the conduit will act as 'a slowly leaking valve', though he also claims that it can expect to resist flow in the wrong direction by a factor 200 times greater than flow in the primary direction.


A photograph of Nikola Tesla himself, from the 1890s.

Modern Research & Applications

Though Tesla designed this valve in the 1920s, it remained out of public interest for decades in the same way many of his other inventions did. Today, however, students and researchers around the world have begun investigating his designs and claims, particularly around the valvular conduit. Research performed in 2020 and published in 2021 shows that Tesla likely designed this circuit in the same fashion as his AC/DC converter. While alternating current (AC) forces the flow of electricity to constantly change direction, direct current (DC) allows the electricity to flow smoothly in a loop. The researchers found that if four valvular conduits were arranged in the same format as Tesla's AC/DC converter and a piston was used to create an 'alternating current' of sorts within the fluid, the valves would convert the flow back into a 'direct current', mimicking the application of the electrical counterpart.

With this knowledge, it is believed that the valve can be used to convert the vibrations of existing motors to pump fluid, saving the need to build, maintain, and power an external pump, which would make engines and machines much easier to power and maintain.

Why Aren't They Used In Widespread Applications?

Unfortunately, the Tesla Valve has not seen widespread adoption yet, even after the recent bout of research performed on it. While there are some promising real-world applications, the modern availability of resources has made it too cheap and easy to simply install an active check valve anywhere that a Tesla Valve would have been used. The active check valve performs the same function as the Tesla Valve, but it entirely restricts fluid flowing in the wrong direction, while the Tesla Valve will slowly leak.

Obviously, even a minor leak is unacceptable in plumbing applications, as this could allow impure water to re-enter the system for use, which will result in health problems. As a result, the Tesla Valve is not used in plumbing applications, and it is unlikely that it ever will be in the future.

That is not to say that the Tesla Valve will not see use in future applications, however. More research is currently being performed to determine whether or not the valve can be used to refine and improve hydroelectric generators, as the natural movement of the waves could be used as the 'piston' that provides the alternating current to power Tesla's AC/DC converter design. Unlike an active valve, the Tesla Valve has no moving parts, which means it requires no maintenance and cannot fail without a core structural failure in the valve itself. In the high-frequency environment of hydroelectric generation, active valves fail frequently and require constant maintenance, while a Tesla Valve can operate nearly indefinitely. Similarly, its use in microfluidics is largely owed to the lack of maintenance, as performing maintenance on that scale can quickly become difficult and expensive.


A Tesla Coil, another of the creators eccentric designs.

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