Needle wash solvent may or may not flow - WKB85721

SYMPTOMS

• Needle wash solvent may or may not flow 

ENVIRONMENT

• Alliance e2695

CAUSE

The needle wash solvent bottle is at the same level or lower than the instrument.

The needle wash pump is a low-pressure pump, and the needle wash solvent is meant to drain under gravity. The pump then draws the solvent away to waste.

The newer Alliance has an enhanced needle wash inlet tubing with a larger ID. The needle wash pump has the same suction force, but with the larger ID there is greater pressure loss at inlet. Velocity at the inlet tubing decreases inversely to diameter increase. So understandably the new design is not able to handle the higher inlet flow without assistance of gravity.

Regardless of new or old design, the needle wash solvent is best placed on top of instrument.

FIX or WORKAROUND

Place the needle wash solvent bottle on top of the instrument, regardless of new or old design.

ADDITIONAL INFORMATION

Recommendations for needle wash solvent can be found in the following documents:

• Operator's guide (715003794)
• Site prep guide (715001178)