Regulating vacuum when the vacuum source varies
The efficiency of any vacuum process depends greatly on the stability of the vacuum that is maintained in the chamber. Examples of this abound, including ensuring a clean diamond with the desired internal structure in artificial diamond manufacturing and or carbon nano tube generation, where a stable vacuum level is crucial in facilitating efficient CNT deposition.
But controlling the level of vacuum in any system can be complicated due to the number of different variables. This can get trickier still when the source of vacuum itself is unstable and variable.
So how do we control the level of vacuum in a closed volume, while ensuring control stability and a swift response? We use a Dual Valve Pressure controller.
In high voltage electrical assemblies, a phenomenon known as corona discharge can be present. In this, an electric discharge is brought on by the ionization of a fluid such as the air surrounding a conductor. In these applications, this leads to significant energy loss, can constitute an unwanted load on the circuit, and these coronas can also generate Ozone, Nitric Oxide, Nitrogen Dioxide and can result in the formation of Nitric acid if water vapor is present. These gases are not only toxic to humans but can also damage the surrounding circuit.
A way to tackle this problem is potting. Potting is a process of filling an electronic assembly with an epoxy to restrict corona discharge and to protect the circuit from impacts and vibrations.
In some of the epoxy potting processes, a constant and stable vacuum source is used to remove air bubbles from the epoxy. As the pressure surrounding this epoxy reduces, the gas entrapped inside it expands and eventually bubbles out. If the epoxy is connected to the vacuum pump directly, it will start boiling rapidly which is undesirable. If the pressure is not low enough then the gas will stay trapped inside the epoxy.
In an application, where stable and fast control of pressures in closed volumes is required, Dual Valve Pressure Controllers provide an ideal solution. As the name suggests, these controllers have 2 valves, one responsible for filling the closed volume and one responsible for evacuating it and, working together, they provide a fast and stable control.
Below is a test condition and a schematic to better explain this setup:
- Supply Pressure: Atmospheric pressure
- Exhaust Pressure (Variable vacuum source): 0-2 PSIA
- Vacuum to be maintained in the manifold: 1 PSIA
- Manifold Volume (Volume to be maintained at the pressure): 2 ft^3
Knowing these parameters enables Alicat to provide valves which are optimized for your application by using our Control Algorithms. This schematic will provide a better insight into these parameters and how they relate to a Dual Valve Pressure controller:
When looking to get a device for pressure control in a closed volume, these parameters enable us to provide you with a device that will best conform to your application:
- Supply Pressure, P1
- Exhaust Pressure, P2
- Size of Closed Volume, VOL
- Expected Flow Rate/ Fill Time requirement
Configure a device out for your system today with the help of our Applications Engineers and control your vacuum with more accuracy and stability.
Ready to find out how we can help improve your process?
Speak to an applications engineer at 1.888.290.6060 or Contact Us to discuss your application.