Our process, research, and academic customers frequently inquire as to our recommendations regarding conditioning a sample flow, before introduction into our process analyzers.* In general, proper conditioning of your sample will preserve the life of the sensors and prevent error in your readings. These are our general recommendations:
- Flow Rate – Process analyzers generally have a “bypass” installed to vent excess pressure to atmospheric pressure. While this is our default configuration, this may not always be the case. Each analyzer is customized to the needs of the application – an analyzer with a bypass installed will generally respond slower (by 5-60 seconds), but can accept higher flow rates without producing a pressure effect on the readings.
- Analyzers with a bypass installed – these analyzers will see no pressure effect on the readings until at least 500 cc/min. Even above that, the difference is statistically within the margin of error. The increase in your readings at about 1000 cc/min will be about +1% of the concentration being measured; i.e. 85% Co2 will read about 85.8%
- Analyzers with no bypass installed – these analyzers will see a pressure effect of about +3% on your readings at 1000 cc/min; i.e. 85% CO2 will read about 88%.
- How do I know if I have a bypass? – Please check with us if you are not sure and we can look up your specific analyzer. Alternately, you can open the top of the analyzer and examine the plumbing arrangement.
- Best Practice – If you are unsure of your flow rate, pass your gas flow through a flow meter before introduction to the analyzer. Use a T-splitter if necessary to vent some of the flow to air, if that is acceptable for your application.
- Particulates – Our internal filter will remove particulates bigger than 0.45 microns which is is sufficient for most applications. However, it is best to filter your sample prior to introduction to the analyzer. Filters are very easy to replace and far less costly than contaminated sensors. Except in very specific, ultra low volume applications, filters should always be used. Filters ship with every new analyzer, and can be purchased here or by sending an email to [email protected]
- Moisture – We recommend that your flow be <95% RH, non condensing. Quantek offers drierite tubes to help mitigate small amounts of moisture. Customers with known moisture, or very high humidity should consider installing a condensing system prior to introducing the gas sample into the analyzer. The internal four layer PTFE filter will block moisture, but this should be depended upon only as a “last resort”.
- Temperature – less than 50 degrees C
- Other contaminants – Your sample should be free of solvents, and free of dioxides that could react with water to form acidic compounds (such as NO2 and SO2).
* Process analyzers can include the Q30 and Q40 series. Of our ‘first generation’ analyzers, the Model 902P O2 CO2 analyzer, Model 905P oxygen analyzer, Model 906 CO2 analyzer, and Model 201 oxygen analyzers are considered “process.”