A syringe is a simple reciprocating pump consisting of a plunger that fits tightly within a cylindrical tube called a barrel. The plunger can be linearly pulled and pushed along the inside of the tube, allowing the syringe to take in and expel liquid or gas through a discharge orifice at the front (open) end of the tube. The open end of the syringe may be fitted with a hypodermic needle, a nozzle or tubing to direct the flow into and out of the barrel. Syringes are frequently used in clinical medicine to administer injections, infuse intravenous therapy into the bloodstream, apply compounds such as glue or lubricant, and draw/measure liquids. There are also prefilled syringes.
A typical plastic medical syringe fitted with a detachable stainless steel needle; the syringe is fitted with a male Luer lock fitting which the needle, which is equipped with a female Luer-Lock fitting (purple), screws into
According to the World Health Organization, about 90% of the medical syringes are used to administer drugs, 5% for vaccinations and 5% for other uses such as blood transfusions.
The threads of the Luer lock tip of this 12mL disposable syringe keep it securely connected to a tube or other apparatus.
Syringe made entirely of glass, with no parts made from plastic nor any other material
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder.
Pistons within a sectioned petrol engine
Internal combustion engine piston, sectioned to show the gudgeon pin.
Slipper piston
Two-stroke deflector piston