Exploring the final frontier is part of a normal day at Alicat. We work on a variety of aerospace applications, projects and experiments that help keep pilots safe, put satellites into space and launch rockets. Alicat works closely with customers in these fields to understand their problems and find straightforward solutions.
Aerospace is a diverse market that utilizes flow and pressure instrumentation for a wide variety of tests and processes. Alicat has worked on projects that:
- Ensure the oxygen masks in commercial and military airplanes flow the correct amount of gas and meet safety regulations.
- Provide liquid mass flow controllers capable of flowing water for cooling systems in propulsion systems.
- Control the lift of high-altitude balloons used to study and understand weather patterns and in other experiments.
- Assist with the pitch, roll and yaw on a satellite using pressure controllers.
- Combine mass flow and pressure control to replicate the atmospheric conditions on Mars to create an environment to test instrument performance in harsh Martian conditions.
- Leak test and characterize the valves that are used in rocket engines.
Leak testing and characterizing the valves that are used in rocket engines.
Leak testing in a lab environment on Earth, where pressure and mass flow controllers are installed into test stands, mass flow and pressure devices do very well with the low leak rate volumes and at low pressure.
However, going to space is a little more complicated. Most rocket components must be tested to higher pressures, similar to those found in the oil and gas processes.
The equipment typically used to do this kind of testing is a dome-loaded regulator. They are used to control the pressure in these tests because they can handle high pressure and the high flow rates experienced in these processes. However, while dome-loaded regulators can handle the pressures they are working with, they suffer from hysteresis. This is due to the mechanics of the valve spring and the behavior of the valve changing depending on its current position and whether it is opening or closing. This can result in a non-repeatable process.
The Alicat solution
To avoid hysteresis and ensure that the process is repeatable, Alicat has provided the high pressure rated dual-valve pressure controllers (PCD) that can tolerate pressures up to 3,000 PSI. To do this, the PCD uses a proportional control valve that is controlled by onboard PID tuning of the device that limits the repeatability issues found with other pressure regulators. PCDs can also be configured with a remote pressure sense port to measure the pressure at the location of regulation to reduce delay and speed up the response time of the system.
To characterize and leak check the valves used for space flight, the high pressure PCDs are used to control static and flowing processes and are paired with an Alicat flow meter. While the PCD is controlling the high pressure on the inlet port of the valve or other component, a Whisper low pressure drop meter is installed downstream of the valve to capture the leak through the valve. Since the valve is exhausting to near atmospheric pressures, a non-restrictive flow device is required to minimize back pressure in the system. The Whisper can also easily switch between N2 and He gas, the most common gases used in these tests, and maintain its accurate flow readings. Switching between gases on the fly is simple through a communication protocol from the devices to a computer or directly from the device’s front panel display.
Meeting the industry where they are: process ports
To meet the needs of this industry, Alicat pressure and mass flow devices can be configured with AS5202. Aerospace Standard and Medium-Pressure process ports are available for easy integration into a test stand. This type of porting has become more common in the aerospace industry and are available on Alicat devices.
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