By David Vanderbeck, OEM Product Manager, KNF Neuberger, Inc.
When determining how to transfer liquid waste within an analyzer,
design engineers must examine many
factors. Though several methods will
work, only one provides optimized system performance and lifetime function.
Clinical diagnostic and laboratory
applications encompass a wide spectrum
of processes, including probe washing,
sample well, or couvette emptying and
washing, slide staining, rinsing, reagent
washing, and general draining. Many of
these processes generate liquids that must
be pumped to waste. These liquids range
from simple DI water to bleach concentrations, to remainders from tests that
include sticky proteins, magnetic beads
and particles, and chemical reaction leftovers. Additionally, molecular diagnostics
involves cell lysing and amplification,
processes that can include elevated temperatures and aggressive chemicals. All of
these differing processes and media add
complexity to pump selection decisions.
System design engineers are encouraged
to talk with KNF applications engineers
to be certain the best pump is selected for
the intended function.
There are two main methods for
removing liquid waste from an analyzer:
direct handling, and waste collection
followed by evacuation.
Method 1 – Direct Handling of Liquid
Liquid pumps can directly handle waste
fluids, and either transfer them to a
collection tank or pump them straight to
waste/drain (Figure 1). The advantag-
es to this de-centralized approach are:
simplicity of pump control, small pump
size, lower pump cost, and possibly fewer
system components. Additionally, the
system is more easily re-configured if
flow requirements change. Frequently,
the same pump model specified for the
probe wash function is also used here
for a better economy of scale, although
high-pressure pumps may be the best
choice for the washing function.
A designer should be aware that the
pump will be pressurizing liquid that will
probably contain biological waste, so extra
caution should be exercised to prevent clog-
ging or leakage. Lines should be smooth, as
short as possible, and of the widest diameter
possible, and pressure limiting devices
should be considered. Pumps are also more
prone to clogging if shards of glass or other
large debris are present in the fluid.
Optimizing Liquid Waste
Handling in Clinical
Diagnostics and Laboratory
Figure 1: Liquid pumps can waste fluids to a collection tank or pump them straight to
waste/drain. (Image Credit: KNF Neuberger, Inc.)
A smart solution strikes the right balance between function, service life, initial cost, and total
cost of ownership.