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How to Backfill a System with Inert Gas [Flowchart]

Products shown in diagram:

Instructions:

Keeping your product as fresh as the day it was made is crucial in today’s concentrate market. To do so, inert gasses may be utilized during and after product production to help preserve and prevent degradation. This handy chart will show you exactly how to perform this technique safely in your lab.

The proper laboratory technique is to utilize inert gas wherever there may be potential for degradation due to oxygen or water, etc. For this reason, even basic extractions and distillations should be backfilled with inert gas or nitrogen (N2). This will help minimize any potential oxygen or water intrusion and reduce unwanted oxidation in your products.

Oxidized bi-products in samples may lead to unwanted tastes or impurities which are undesirable in consumer products. The addition of a nitrogen/inert gas backfilling system will lead to an overall better-quality product, due to the reduced interaction with free oxygen (O2).

This is achieved through a relatively simple process outlined below:

  1. Nitrogen (N2) or inert gas tank is connected to a regulator for flow control.  Little amounts of pressure are required for backfilling as systems are typically under vacuum.

  2. Connect a vacuum/pressure-safe hose line from the regulator to a bubbler check valve (BCV) or pressure release valve (PRV).  The PRV should be set to atmosphere, or if using a glass bubbler check valve, filled with vacuum pump oil or similar.

  3. Connect the BCV or PRV to a tee, having the connection from the inert gas source opposing (inline) with the BCV/PRV. Utilize vacuum/pressure-safe hose line

  4. Connect the side-arm of the tee to a three-way valve; utilize vacuum/pressure-safe hose line.

  5. Connect the three-way valve to the vacuum system; utilize vacuum/pressure-safe hose line.

  6. To backfill with nitrogen/inert gas, the system must be closed and under vacuum; once setup is assembled and sealed, pull vacuum via the vacuum system.  With the inert gas flow regulator closed, open the three-way valve to the inert gas source.  Doing this will remove any atmosphere from within the backfilling setup.  Re-close the three-way valve.

  7. Upon reaching high-vacuum levels (sub 500 micron/mTorr) close off valve to vacuum system.

  8. With all valves closed, slowly open the flow regulator to allow a slow stream of inert gas to flow through the BCV/PRV.

  9. Open the three-way valve to inert gas source and allow nitrogen/inert gas to backfill into the system until either the BCV/PRV releases excess pressure (pop sound).

  10. Close inert gas valve and reopen vacuum valve. (IMPORTANT: Never have both valves open at the same time).

  11. Repeat steps 4 through 7 (3) times or as desired to insure all atmosphere/oxygen (O2) is removed.

  12. Begin normal operation of vacuum/pressure system equipment.

The next time you are wondering how to backfill your vacuum system with nitrogen or another inert gas, just let this handy chart be your guide!

** It should be noted that the backfill setup can be connected to any vacuum system and at any point the the system; This diagram and set up pertains to Short Path Distillation Kits.