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Our recent webinar, Mitigating Risk: Highly Reliable Alternatives to Pyrovalves, addressed the growing challenges defense engineers face as mission requirements evolve. Attendees explored why program teams are reconsidering pyrovalves, what alternative actuation technologies exist, and practical considerations for transitioning away from traditional pyrovalves toward safer, more reliable alternatives.
The full Q&A from the session is compiled below.
Question |
Answer |
|
| 1. | How do your alternative options compare to a pyrovalve’s size and weight? | The Latching Mechanical Valve and Pneumatic Isolation Solenoid Valve are comparable in both size and weight (and often smaller and lighter than a typical pyrovalve). Each valve weighs approximately three ounces and is roughly two inches long with a diameter of less than one inch. |
| 2. | What latching pressures are offered with the Latching Mechanical Valve? | The Latching Mechanical Valve uses a detent feature to establish the latching pressure. Our designs are currently offered with latching pressures of 20 to 500 psid.
Latching pressure should be determined based on the application in which the valve is used. In missile fuel isolation applications, for example, latching pressure is a function of fuel tank volume, environmental storage conditions, and the pressure required to prime the fuel pump for engine start‑up. While higher latching pressures can improve sealing performance, the pump must still be capable of generating sufficient pressure under all operating conditions to reliably latch the valve open. |
| 3. | How do the response times of your solutions differ from pyrovalves? | Response times are comparable.
Pyrovalves typically require approximately 20-50 milliseconds to complete a full opening or closing event. The Pneumatic Isolation Solenoid Valve will respond in as little as 10 milliseconds when operated with pneumatics, and within 15-40 milliseconds when used with liquids. The Latching Mechanical Valve will also respond in 10-40 milliseconds. It should be noted that these valves function best when flow and pressure are increased as rapidly as possible. Once the valve is latched in the open position, the valve will remain open, allowing the pump to ramp up or down as required to supply fuel to the engine. |
| 4. | How should I decide between using the passive (Latching Mechanical Valve) or non-passive (Pneumatic Isolation Solenoid Valve) solution? | This decision should be based on the system in which the valve will be used. First, you’ll need to determine whether there is a change in the fluid’s pressure that will necessitate a passive solution. If the fluid is stored in a high pressure state and there is no mechanism to further increase pressure, you’ll want to consider a non‑passive solution. If specific EMI requirements prevent the use of electric controls, a passive solution should typically be considered. |
| 5. | Are there any concerns that the Mechanical Latching Valve could latch open prematurely? | There should be no concern when the valve is properly specified for the application. The latching mechanism is based on our detented shuttle valve design, which has been successfully used in the aerospace industry since 1991.
We work closely with our customers to determine the appropriate latching pressure based on their system requirements. Every part we build is 100% tested in accordance with the inspection drawing, ensuring that latching performance is verified prior to shipment. |
| 6. | How do you reset the Mechanical Latching Valve? | To reset our Mechanical Latching Valve, the outlet port of the valve will need to be disconnected. A simple gauge pin tool can be used to press on the poppet and return it to the normally closed position. The typical force required to reset the valve is 5 lbs. Once the valve is reset, the outlet port can be reinstalled, and the valve is ready for normal use. |
| 7. | How does your Pneumatic Isolation Solenoid Valve integrate into typical fluidic systems? | Standard Lee solenoid valves are offered with our proven MultiSeal® technology, designed to simplify port layout and deliver significant space savings. This unique design offers a smaller, easier way to produce an interface fit compared to solenoid valves that use traditional O‑rings. It creates a reliable static seal between the valve ports and the external environment, making it especially well-suited for applications with existing manifold blocks.
For applications plumbed with tubing, we offer standard adapters, including AS and tube‑stub porting. Custom interface solutions are also available upon request. |
| 8. | Can the Pneumatic Isolation Solenoid Valve meet rideshare vibration and leakage requirements for space applications? | Yes. Our solenoid valves are designed to meet typical requirements for space applications, including vibration and leakage. Each design has been qualified and acceptance tested. For our standard bubble‑tight valves, pneumatic testing is typically performed. Helium leak testing is available for applications with more stringent leakage requirements.
Standard vibration qualification is conducted in accordance with RTCA/DO‑160G and military standards (MIL‑STD‑810H), and qualification reports are available upon request. We can also offer custom designs with higher vibration profiles to meet requirements beyond what is common for most rideshare applications. |
| 9. | What is the rated service life of these valve options? | Valves from The Lee Company are designed to last for the life of the aircraft. For fuel isolation applications, our valves comply with the 20‑year fuel storage and shelf‑life requirement. We also work closely with our customers to review their specific applications to ensure material compatibility and will offer material changes when needed to ensure long‑term performance. |
| 10. | How do you verify your leakage claims? | Each valve is produced to a specific leakage requirement. For our pneumatic solenoid valves, we typically test using a nitrogen source on the inlet and monitor the valve outlet for leakage. |
| 11. | How do the costs of these two options compare with typical pyrovalves? | Pyrovalves vary widely in cost, with some high end units as expensive as a new car. By contrast, our valves are standard commercial components used across multiple industries, so their pricing is generally more consistent and competitive. The real savings, however, emerge when considering total installed cost — driven largely by the specialized requirements and single-use nature of pyrovalves. |
| 12. | Can these valves be cleaned for space applications? | Yes. While The Lee Company has an established in-house cleaning procedure for all standard parts, we can also clean components to industry standards such as IEST-STD-CC1246 and include Nonvolatile Residue (NVR) verification. |
| 13. | How much flow are these valves good for? | When the latching valves are fully latched open you can expect ~0.5 GPM flow at 40 psid from the smaller -02 fittings, and over 2 GPM flow at the same 40 psid with our -04 fittings. These designs can also be scaled up to use large fitting sizes for higher flow applications. |
| 14. | Do you offer a solenoid solution that can maintain leak-tight performance for Nitrogen gas storage of 6000 psig over a 10-year duration? | Yes. Our standard offering (product number: SDPX0507400B) is a bubble-tight solenoid valve design that is rated for operating pressures from up to 6000 psid. This valve falls within our Pneumatic Isolation Solenoid Valve product line and is well-suited for nitrogen systems. Our valves are typically designed for the life of an aircraft and are expected to function well beyond ten years. Additionally, this valve can be offered with the magnetic latching feature as a custom solution. |
| 15. | How do solutions from The Lee Company compare to pyrovalves in terms of reliability, particularly after long periods of dormancy? | Our valves are constructed from corrosion‑resistant materials that are compatible with most gases, fuels, and oils. As a result, they are expected to operate to their rated requirements even after extended periods of dormancy, whether they are stored in their original packaging or installed in a customer’s system. Our solenoid valves have been in use throughout the aerospace industry for decades and have been evaluated through accelerated life testing, extensive environmental testing (including MIL‑STD and RTCA/DO‑160), and reliability analyses (MTBF), demonstrating significant margin relative to mission operating requirements. |
Watch our webinar to learn about solutions that offer increased design flexibility and improved system performance across critical defense applications. We will share best practices for transitioning away from traditional pyrovalves – what to use instead, how to make the switch, and ways to ensure mission success.
Explore how Lee components integrate into next‑generation fighter aircraft across general, flight, engine, weapons, and landing systems. Use this interactive to discover how precision‑engineered solutions from The Lee Company work together to deliver reliability, responsiveness, and mission‑critical performance in the most demanding defense environments.
Always verify flow calculations by experiment.
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