Do You NEED TO CONTROL GAS FLOW TO A SINGLE SET POINT?
The control of gas flow is a major, rapidly evolving field of gas dynamics. It implies a small change in a configuration, ideally serving a sizeable engineering benefit. This change may be accomplished by static or dynamic devices. Static devices, like orifices or roughness elements, are steady and do not necessarily require energy. Active control requires actuators which may require energy (for instance solenoid valves and actuators). The actuation may be pre-determined (open-loop control) or dependent on sensors monitoring the flow state (closed-loop control).
Dynamic or static gas flow control?
Many engineers think of MFCs (mass flow controllers) when there is a need for a specific gas flow within an accuracy of 1% in the design phase. Once the whole system is tested/tweaked, the MFC is often set to a single point and the gas supply (medium, inlet pressure, temperature and other conditions) remain the same.
The MFC does the job, but it is a considerable initial purchase if you compare this to a SFC (Static Flow Controller), which is priced significantly lower, and besides that needs calibration every year. You might be able to reduce the costs up to 70% over standard industry flow controllers, depending on your application.
The technique used in a SFC also creates a laminar flow.
What is SFC?
A static flow controller (SFC) is a device used to control the flows up to 40 slpm of gases with a high accuracy. A static flow controller is designed and calibrated to control a specific type of gas at a particular setpoint. The SFC can be configured to a specific static operating condition, including vacuum, with +/- 1% flow accuracy. This reliable mechanical solution will control the rate of flow to the given setpoint with a +/- 0.1% repeatability. The SFC can be configured to your desired connections like ¼ “ Face seal or 1.125” IGS C-seal connections. SFC’s are 100% testedafter calibration and each unit comes with a quality certificate showing its flow rate data validated to a NIST primary standard (very similar to MFC!), He leak tested and need no re-calibration.
Designed for high tech applications
The design is mechanical: simple and tamper proof. All static flow controllers have an inlet port, an outlet port and a porous metal element inside. The SFC has a compact design, which saves space in critical designs . It is built for UHP applications; made from 316L Stainless steel, with a 10 Ra surface finish manufactured in an ISO class 5 cleanroom which makes it extremely suitable for semiconductor processing. You may need a static laminair flow during semiconductor processes such as etching, chemical vapor deposition, epitaxial deposition, ion implant, atomic layer deposition, chamber purge, wafer transport modules, load locks and lens cooling. But you can think of many other OEM or research applications where a single set point gas flow is needed.
To determine the right static flow controller, you need to collect the following data:
- Desired ﬂow rate (in sccm or slpm)
- Specify gas (ex. Nitrogen)
- Upstream pressure (in psi or bar)
- Downstream pressure (in psi or bar)
- Specify connection (custom optional)
- Specify operating gas temperature (°C or °F)