Hi everyone, I hope this message finds you all well.
I've recently been put in charge of a Residual Gas Analyzer, and it is the first time I have dealt with high vacuum and this type of analysis.
One of the improvements desired by my superior is to get a more precise reading of the gas composition coming out of our columns.
The current issue revolves around the non-linearity of signal vs. concentration. Despite making regular calibration curves and factors, analyzing a low gas mixture concentration is the best possible approach.
Right now, the procedure is just to stick the ampoule in the quick-fit valve, and that's it. This is not the best approach, and I'll spare you the list of uncertainties this protocol is causing.
I want to use He to mix it with the analyte in an anti-chamber to reduce the concentration and to have an exact pressure before starting the measurement.
Assuming I have an ampoule with roughly constant pressure and gas quantity, Is there a passive method with which I can ensure that I'm inserting a constant amount of He? Won't the pressure change in the He bottles upon use change the amount of He that I'm pouring in the antechamber? Won't adding at least two additional connections screw with my vacuum?
Any pointer, literature, book, or suggestion is appreciated.
Thanks in advance,
Bruno.
To inject always a constant amount of gas at a constant pressure in an antichamber, you can use a mass flow controller (MFC). An MFC is a device that regulates the flow of a gas by controlling the mass of the gas that passes through it in a given amount of time.
To use an MFC to inject a constant amount of gas into an antichamber, you would first need to determine the desired flow rate of the gas. You can do this by measuring the pressure and temperature of the gas and using the ideal gas law to calculate the mass flow rate. Once you know the desired flow rate, you would need to set the MFC to the appropriate value. The MFC will then regulate the flow of gas so that it always flows at the desired rate.
It is important to note that the MFC will only be able to inject a constant amount of gas if the pressure and temperature of the gas remain constant. If the pressure or temperature of the gas changes, the MFC will need to be adjusted to compensate for the change.
Here are some additional tips for injecting a constant amount of gas at a constant pressure in an anti-chamber:
- Use a high-quality MFC. A high-quality MFC will be more accurate and reliable than a low-quality MFC.
- Calibrate the MFC regularly. Calibrating the MFC ensures that it is accurately measuring the flow rate of the gas.
- Monitor the pressure and temperature of the gas. If the pressure or temperature of the gas changes, adjust the MFC accordingly.
By following these tips, you can ensure that you are always injecting a constant amount of gas at a constant pressure in an anti-chamber. Here are some additional options for injecting a constant amount of gas at a constant pressure in an anti-chamber:
- Use a piston pump. A piston pump is a mechanical device that can be used to pump gas at a constant rate.
- Use a diaphragm pump. A diaphragm pump is another mechanical device that can be used to pump gas at a constant rate.
- Use a gas cylinder. A gas cylinder can be used to store and dispense gas at a constant pressure.
The choice of which method to use depends on the specific application. For example, a piston pump may be the best option for a laboratory setting, while a gas cylinder may be the best option for a field setting.
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