Nitinol Actuated Valves

For the last 100 years, miniaturization has been one of the driving factors behind technology.  This is most evidenced in the computing industry, where an Apple watch has many times more computing power than a room-sized computer did 80 years ago.  Unfortunately, actuation technology hasn’t changed much in the last 80 years.  Yes, improvements have been made, but it’s on the same order of magnitude as it was 80 years ago—or 100 years ago.

Figure 1: Actuator (Black) Inside of the Valve Housing

Enter nitinol:  Nitinol actuators are a new possibility.  They can be packed into ultra dense packages that allow actuation where actuation was never possible before.  The CAD image at right is taken from an actual customer project.  Prior to nitinol, the actuation solution made up 40% of the total product.  After nitinol, the customer’s product was able to fit into spaces that were never feasible before.  Not only that, but the nitinol actuator was cheaper than the previous solution!

What is Nitinol? Nitinol is a mixture of nickel and titanium that demonstrates the shape memory effect (SME).  While other alloys exhibit SME, it is much bigger in nitinol, making it the most commercially viable.  For more technical information about nitinol, visit: https://www.kelloggsresearchlabs.com/nitinol-faq/

Power Density: Nitinol has the highest power density of any actuation technology available.  While high pressure hydraulic systems operate at 5,000PSI (35MPa), nitinol routinely operates at 25,000PSI (175MPa) and certain ternary alloys can operate at double that.  This means that a 3” diameter high pressure hydraulic cylinder could be replaced with a 1” straight wire actuator, resulting in a 60% weight reduction—not counting the supporting hardware.  The image below is an actuator for a deep sea oil and gas valve.

Figure 2: Deep Sea Oil and Gas Valve Actuator
Figure 3: Solenoid Replacement Size Comparison

If you’re currently using electric solenoids, then nitinol offers a world of improvement.  The image at right shows a project that we did for a customer.  The solenoid, not only was it noisy, but it occupied 2 cubic inches (32,000mm3), weighed 4 ounces, and drew 2A of current while it was activated.  The nitinol actuator, by comparison, occupied 37mm3 (0.001 cubic inches) weighed less than 1g, actuated on 0.5A (which was then reduced to 0.1A during steady state conditions), and we were able to deliver the product for half the price of the electric solenoid!

Ancillary benefits: Reducing actuator size is just one of the many benefits

  1. Vibration Damping: With damping efficiencies exceeding 90%, your nitinol actuator can also be used to dampen vibrations caused by flow through the valve.
  2. Non-corrosive: Nitinol is one of the most non-corrosive materials on the planet.  For this reason, it’s often used in deep sea applications because, even after decades of service, nitinol retains its full capabilities.
  3. Water Hammer: It’s no secret that water hammers are incredibly damaging to infrastructure.  Nitinol has incredible shock dissipating capabilities, such that a partially open valve can dissipate much of the energy of the water hammer
  4. Durability: One of our customers actually paid us to shoot their nitinol product with a rifle.  A 1mm thick sheet of nitinol safely stopped a 7.62mm bullet. 
  5. Temperature Control: Nitinol is thermally active.  That means that the nitinol actuator can double as a sensor, opening valves when temperatures reach desirable (or unsafe) levels.

So, what can Nitinol do for you?

Leave a Reply

Your email address will not be published. Required fields are marked *