Dispensing Tip

Changing Out Syringes

Successful dispensing depends on a properly primed fluid path that is free of air bubbles, including all wetted surfaces from the syringe to the needle tip. Air bubbles are most often the root cause of dispensing inconsistencies, such as tailing, dripping, dispense voids and weight variations. Bubbles are most commonly introduced into the fluid path during the syringe change and priming process.

When changing syringes, it is important not to introduce air into the fluid path. If there is fluid left in the syringe, and you are fairly certain that air has not been introduced into the pump through the syringe, follow these steps to change the syringe:

1. Turn the dispenser off. Open the doors and remove the cooler jacket from the syringe (if present).
2. Remove the receiver head.
3. Remove the syringe. Make sure the 90° luer elbow fitting remains attached to the valve (if present).
4. When the syringe is removed, a small void forms in the end of the valve luer lock adapter [Fig. 1]. Use a small amount of fluid from the old syringe to fill this void. Visually inspect the luer lock adapter for air bubbles. If air bubbles are present, a new fluid syringe should be used to fill the void. Also check the new syringe for air bubbles. If there are bubbles present, use a different syringe [Fig. 2].



Figure 1



Figure 2

 

5. Remove the cap from the new syringe of material.
6. Holding the syringe tip-side down, allow the fluid to completely fill the syringe tip [Fig. 3].



Figure 3

7. Connect the syringe to the luerlock adapter on the pump. If material seeps over the fittings, wipe it clean.
8. Reinstall the receiver head.
9. Reinstall the syringe cooler (if present).
10. Close the dispensing system doors.
11. Restart the equipment.
12. Millennium systems only: Purge the system long enough for the fluid from the new syringe to begin flowing out the dispense tip. Make sure valve pressure and valve speed are set to the desired settings. Then measure the flow rate until you have two consecutive flow rate measurements that are within +/- 2% of each other.

This simple syringe change process is not recommended if one of the following situations exists:

• The syringe has been completely emptied while the dispenser was operating. It is likely there is air in the valve.
• The syringe contains fluid that has exceeded its pot life.

For either situation, you must fully clean and dry the valve or pump, and follow set up procedures. Refer to your operations manual for detailed instructions.

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