A device that is taken for granted in the scientific, medical, and research laboratories is the precision scientific pump. This simple yet extremely useful machine does the work of what could be manual tasks and is usually overlooked until it breaks down. The laboratory scientific pumps in today's instruments have not changed much in many years; because they work well in the configuration they are currently designed.
The main types of scientific pumping used today are peristaltic pumps. This design was necessitated in the development of the dialysis machine, which is used when a patient's kidneys fail to filter contaminants and waste materials from the blood. The pump was designed so that when pumping blood through the machine, the blood would not be damaged in the pumping process. The peristaltic pump is so named because of the action on the tubing used to transport the fluids.
Peristalsis is the action of squeezing a tube linearly in sequence, moving fluid in a forward motion. The round peristaltic pump design is simple: Rollers are set inside a spinning wheel, and the rollers rest on top of the tubing holding the fluid. As the wheel spins, this squeezes the tubing in a flowing and constant manner, thus pushing the fluid along the tubing without damaging it.
This design is incorporated in precision scientific pumps. The motor that is attached to the pumping system can be step-driven, or made to respond in very small increments. This can give an exact amount of fluid to the instruments that are doing the testing procedures. As the motor steps rotationally, the peristaltic rollers push the fluid in the exact calibrated amount, thus acting as an autopipette system for administering precision doses of reagents or samples.
Other scientific pumps are piston controlled. Many medical analytical instruments use this type of pump for the rinsing of probes, the mixing of reagents, and even the mixing of samples and diluents. Many of these piston scientific pumps are used for the purified water delivery system. They can be calibrated and adjusted for temperature variations and type of fluid used.
There are air pumps that use air pressure to move a membrane in a pumping motion. The fluid needing to be moved is on the other side of the membrane, and as the air pressure moves on the opposite side, the flexing of the membrane pumps the fluid through valves that are arranged to keep a constant flow of liquid. These types of scientific pumps can be calibrated to give a certain pressure flow, or even be used to increase fluid pressure within the instruments' tubing system.
Some scientific pumping is done by gravity and precision valve control. The reagent is installed above the work area, and as reagent is needed, precision valve systems are controlled electronically to deliver the precise amount of the reagent during the instruments run.
Another scientific pumping method is done by impeller. This is useful when mixing the purified water or other reagents prior to testing. The impeller can be electronically controlled to run at precision speeds or times, and are excellent for mixing.
It is plainly seen that the scientific pumps listed are needed and taken for granted. As they work hard in the background, we will only notice them when they stop working properly.
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