Installing the 7800-113 reduced flow rate kit in LI-COR Trace Gas Analyzers

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The reduced flow rate kit (part number 7800-113) is an accessory for LI-COR Trace Gas Analyzers that enables the devices to operate at a flow rate near 70 sccm rather than the standard flow rate of 250 sccm. This document describes part number 7800-113, which is a replacement for the older kit (part number 7800-112).

What's what

The kit includes the following pre-assembled components.

Description Part #
Quick connect union (2) 300-03123
Flow orifice; 0.006" (1) 301-18700
Bev-a-line tubing; 3.2 cm (2) 222-01824

By installing the kit you will modify the internal flow routing of the instrument. After installing the kit, the instrument will start up in the suitable operating mode. The 7900-113 reduced flow rate is compatible with closed-loop applications. The old one (7900-112) is not because the inlet and outlet flow rate are different.


The kit is supported by instrument firmware version 2.0.25 and newer (go to, select an instrument, and then click Software Downloads). One firmware updater can be used to update all Trace Gas Analyzer models.

  1. Power off the instrument before installing the kit. 
  2. Identify the tube that connects the pump to the optical bench.
  3. Observe the orientation of the T-fitting. In early models, this tube comes off of the stem of the T. In later models, it comes off of the cross of the T. In either case, the tube connects the T-fitting to the pump.
  4. Cut the tube where indicated.
  5. Observe the flow direction indicator on the assembly and install it between the two cut ends with the arrow pointing from the optical bench to the pump.
  6. For each quick connect, insert the tube and push firmly until it stops.
  7. Configure the software for the low flow kit.
  8. Power on the instrument and connect to it using a computer or mobile device. The instrument will start in the standard operating mode. Starting up in the standard mode while the Reduced Flow Rate Kit is installed will trigger warnings and errors; ignore them for now.
    1. Click Options > Settings > Software. Under Configuration, select Reduced Flow Rate.
    2. When prompted, click Yes, I'm sure to proceed.
    3. The instrument will restart and initialize with the reduced flow rate configuration.

If you want to restore the normal flow rate, remove the reduced flow rate kit, change the instrument configuration to Standard and restart. The cut tubes can be reconnected with a quick-connect union from the kit.