Instruction Manual

Operation 35

Needle Sizes and Types

Changing the size of the dispensing needle can change the width of the fluid line dispensed. A larger

needle will create a larger line. However, using a smaller needle does not affect the flow rate. The

DP 3000 Series pump accepts Luer lock dispensing tips. Use only the dispensing tips provided in the

VK 6000 valve kit.

" NOTE You should always use the largest diameter needle possible for your application to

place the least amount of stress on the stopcock. Higher viscosity fluids can destroy the

stopcock if used with a too small needle size.

Preventing Needle Movement

If the stopcock and needle assembly is not assembled correctly, the needle may move during the

dispensing process. This movement does not impact pump placement accuracy, and the movement is

repeatable—the needle always returns to its original position. However, proper assembly of the stopcock

and needle can eliminate needle movement.

There are four contact surfaces on the DP-3000 that provide support for the stopcock and needle

assembly. See Figure 3-24.

1. The side of the sliding bracket supports the back of the stopcock.

2. The bottom surface of the stopcock rests on the upper surface of the Luer clamp block.

3. The Luer clamp ring is clamped into the Luer clamp block.

4. The pump taper on the bottom of the pump chamber is forced into the stopcock taper. This

mating provides a seal as well as a downward force to push the stopcock against the

surfaces mentioned in points 1 and 2 above.

Figure 3-24 Stopcock and Needle Assembly Support

Stopcock and needle assembly

slides down into Luer clamp

block

(3) Stopcock Luer lock

ring inside Luer clamp

block (not visible here)

(2) Support from the

Luer clamp block to

the stopcoc

(1) Side of sliding

bracket

(4) Stopcock Taper

(4) Pump Taper