Air generator for GC

We need to use air generator for 8 GCs with FID Detector. Each FID uses 350 mL/min air. So for 8 FID, 2.8L air will be sufficient? Is it ok to go for an air generator that supply 3L of air/min or we need to go for a higher option? Kindly advise

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  • Hello  ,

    The flow in mL/min is a calculated value based on the P delivered to the FID.

    I am not sure what type of GC you are using, but will use the 8890 manual below for reference. Table 17 at page 44 shows a range of 55-100 psi for air for FID detectors. Generally, 60-80 psi for delivery pressure is a good enough range for most cases, for air for an FID. Depending on the model of GC, the maximum allowed pressure on the FID might be lower than 100, so make sure to check the requirements for that if the GCs are of different model than the 8890.

    Agilent 8890 GC Site Preparation Guide

    The pressure required to deliver a certain amount of flow at one temperature is different to the pressure required to deliver the same flow at a higher temperature. So just going off of flow requirements can lead to problems further on.

    I don't have an idea of how the air generator supplies gas to the GCs, but you need to make sure you need to deliver the required pressure to the FID (up to 100 psi per GC -if 8890-, but not higher than that). 

    Apart from instrument requirements, there might be other factors to take into account; such as the length of the gas lines to the GC, where the air generator is installed (same room, different room, different floor etc). The air generator manufacturer should be able to address these questions.

    Maybe other users with similar configurations would be able to provide some insight as well. 

Reply
  • Hello  ,

    The flow in mL/min is a calculated value based on the P delivered to the FID.

    I am not sure what type of GC you are using, but will use the 8890 manual below for reference. Table 17 at page 44 shows a range of 55-100 psi for air for FID detectors. Generally, 60-80 psi for delivery pressure is a good enough range for most cases, for air for an FID. Depending on the model of GC, the maximum allowed pressure on the FID might be lower than 100, so make sure to check the requirements for that if the GCs are of different model than the 8890.

    Agilent 8890 GC Site Preparation Guide

    The pressure required to deliver a certain amount of flow at one temperature is different to the pressure required to deliver the same flow at a higher temperature. So just going off of flow requirements can lead to problems further on.

    I don't have an idea of how the air generator supplies gas to the GCs, but you need to make sure you need to deliver the required pressure to the FID (up to 100 psi per GC -if 8890-, but not higher than that). 

    Apart from instrument requirements, there might be other factors to take into account; such as the length of the gas lines to the GC, where the air generator is installed (same room, different room, different floor etc). The air generator manufacturer should be able to address these questions.

    Maybe other users with similar configurations would be able to provide some insight as well. 

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