Thermo Electron 3940 Series, Operating And Maintenance Manual

Page: 17 / 78

The CO
2
source must be regulated at a pressure level of 15, ±5 psig.
Higher pressure levels may damage the CO
2
control system. The user
should determine the most economical pressure level, between 10 and 20
psig appropriate for the desired CO
2
percentage in the chamber. Use only
sufficient pressure to maintain recovery time after door openings.
To connect the CO
2
supply (Figure 1-5):
1. Connect the CO
2
tubing to the 1/4”
hose fitting installed in the CO
2
inlet.
2. Check the tubing connection for leaks.
The Watlow SD CO
2
controller's upper display shows the actual CO
2
content inside the chamber. The lower display shows the CO
2
setpoint.
Before setting the CO
2
content, allow the chamber temperature and
humidity to stabilize. Do not open door during the stabilization period.
To set the CO
2
content (0% to 20%), press the Up or Down Arrow keys
on the Watlow SD Controller.
1-8 Model 3940 Series Thermo Electron Corporation
Section 1
Installation and Set-Up
Connect the CO
2
Source
(continued)
Figure 1-5. Inlet Connections
Set the CO
2
Content
Figure 1-6. Watlow SD Control