Thermo Scientific Accela Open Autosampler Hardware Manual page 70

2
Installing the Accela Open Autosampler
Injection Valve
Valve Needle Guide and Needle Seal
52 Accela Open Autosampler Hardware Manual
All valves are equipped with a special valve needle guide fitting. This fitting has a wide
diameter to connect with the syringe needle guide on the injection unit. The valve needle
guide also has a countersunk hole to guide the syringe needle into the injection port.
Figure 48 shows an example of the setup with the standard valve, Cheminert type.
Figure 48. Valve needle guide and valve needle seal
The valve needle guide holds the needle seal. The needle seal, which is a short length of FEP
tubing, forms the seal around the syringe needle. A stainless steel ferrule is tightened around
the FEP sleeve to ensure a leak-proof fit.
 To ensure reproducible sample injection and minimize carryover
1. Properly install the valve needle guide and the valve needle seal.
2. Change the valve needle seal at regular intervals.
3. Set the needle penetration depth accurately
page 48).
To specify a maximum number of penetrations into the needle seal is not practical. You might
want to check the tightness of the seal daily or weekly when first using the Accela Open
Autosampler to gain experience with the specific use in the laboratory related to the
application.
 To test the tightness of the seal
1. Take the needle seal out of the valve port.
2. Manually insert a syringe needle gauge 22 (or gauge 22S) from the top, down into the
tube, and past the sealing point of the ferrule.
3. If you observe a restriction, continue to use the needle seal. If not, replace the needle seal.
("Injection Valve Reference Points" on
Thermo Scientific