Fluidic Connections; Flow Fit Connections - Hach QC8500 Series 2 User Manual

4.3 Fluidic connections

4.3.1 Flow fit connections

1 Union fitting
2 O-ring (2x)
Tee connectors, union connectors and pump tube adapters are all examples of flow fit
connections. Tube connectors used on tee connectors, union connectors and pump tube
adapters pass Teflon tubing through two Viton
connector is finger-tightened to compress the O-rings around the tubing for a
leak-proof seal.
Tube connectors used on the injection valves do not require O-rings or ferrules.
Note: Injection valves use one-piece fittings.
Figure 37 Teflon tubing connection to a union fitting
When a fitting is new, the Viton O-rings are very tight. In this case, unscrew the tube
connector and remove the O-rings with the O-ring remover provided in the accessories
kit. Insert the Teflon tubing through the center of the connector and the two O-rings,
making sure that the threaded end of the connector is towards the tubing end. Screw the
tube connector in the union fitting. Finger-tighten the screw connector.
Note: The tubing may become slippery due the natural oil on fingers. Use a small piece of paper to
hold the tubing to avoid this problem.
After some use, the O-rings will become more flexible and allow more rapid
tube connections.
To make flow fit connections:
1. Insert the tubing. Loosen the tube connector by one quarter of a turn.
2. Slide the tubing through the connector into the union fitting until it stops.
3. Press firmly to push the tubing through the O-rings. Do not crimp the tubing.
4. Finger-tighten the nut. To make sure that a seal is made, gently pull on the tubing. If a
seal is made, the tubing will not easily pull out of the fitting.
®
O-rings into a seat
1 2 3
3 Tube connector (nut)
4 Teflon tubing
Operation
(Figure 37). A tube
4
37