Thermo Scientific EA IsoLink IRMS System Operating Manual page 160

b. Move the O-ring along the tool up to reach the border.
c. Move the tool on the shaft body up to reach the internal seat.
d. Move and inset the O-ring into the internal seat, then remove the tool.
4. Insert the second O-ring into the middle seat of the shaft.
a. Place the second O-ring, with the lip turned inwards, on the conical section of the tool.
b. Move the O-ring along the tool up to reach the border.
c. Move the tool on the shaft body up to reach the middle seat.
d. Move and inset the O-ring into the middle seat, then remove the tool.
5. Insert the third O-ring into the external cavity of the shaft. The use of the tool is not necessary.
a. Manually place the last O-ring, with the lip turned outwards, into the external seat.