Syringe-type needles are common- ly used to meter or dose liquid samples onboard clinical diagnostic and analytical lab equipment. These
needles must be washed after each use
to avoid cross-contamination with the
next test. Needle washing has long been
a successful application for lab pumps.
This article explores different methods,
Washing the needle
pump types and popular options to con-
sider, and offers suggestions for process
optimization. In addition, other system
components, such as cuvettes and micro-
titer plates, can be handled with similar
The typical needle wash process (Figure
1) involves forcing DI water, solvent, surfac-
tant (soap solution), sodium hypochlorite
(NaClO), or other liquid through a needle
that is positioned inside a wash station (vol-
ume 10 to 25 mL open-top well; 5 to 50
mL of liquid typically consumed). The wash
liquid is pumped at a rather high speed to
cleanse the inside of the needle. As the wash
liquid exits the needle and accumulates in
the well, the liquid level rises, thereby also
cleansing the outside of the needle. Some-
times, the geometry of the well is specially
designed to enhance the swirling action of
the wash fluid.
The used wash fluid is then aspirated
from the well by one of two methods:
1. The cup has a drain at the bottom
that is opened by a valve connected to a
vacuum source (Figure 1B).
2. A separate waste collection needle
is positioned alongside the main needle
Needle Washing for Analytical
With a variety of configurations available, diaphragm pumps
have proved critical for the thorough washing
of syringe-type needles.
by Dave Vanderbeck, Product Manager, KNF Neuberger, Inc.