Thermo Scientific Accela Open Autosampler Hardware Manual page 109

Nut and Ferrule Tightening
Thermo Scientific
• Tube not cut square (see
• Wrong type of ferrule or nut used (see
• Trapped air bubbles (see
Figure 57 provides an illustration of the terms used for tubing connections.
Figure 57. Terms for tubing connections
Such mistakes lead to these issues:
• Dead volume
• Peak deformation or peak splitting
• Carryover effects
• Decreased resolution of the tubing between column and detector
You can prevent issues with tubing connections by observing the following basic rules.
 To tighten a nut and ferrule stepwise
1. The first important rule when tightening a nut and ferrule is to proceed stepwise.
a. Tighten the nut by hand as much as possible.
b. Continue to tighten using a wrench until you feel resistance. Add one or two quarter
turns to reach the sealing point.
c. Open the connection and remove the assembly to inspect the pilot distance. See
Figure 57.
d. Install the assembly again and, first, manually tighten the nut. Then, use the wrench
to reach the same sealing or resistance point as reached in step 2 and add one quarter
turn extra for the final seal.
e. Check the seal when liquid is pumped through the system. In case a leak is observed,
tighten once more by another quarter turn. Always move from a leaking to a tight
seal; never move backward from an overtightened seal.
"Tube Not Cut Square" on
"Wrong Nuts or Ferrules Used"
"Avoiding Trapped Air Bubbles"
Accela Open Autosampler Hardware Manual
6
Troubleshooting
Troubleshooting Considerations
page 93)
on page
on page 95)
94)
91