Syringe

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A syringe is a simple reciprocating pump, consisting of a plunger (the piston) that fits tightly within a cylindrical tube (or barrel). Syringes tend to come with needles.

Operation

To operate a syringe, there are several techniques. The "lazy" technique involves grabbing the two plastic "ears" from the barrel with two fingers, while the piston can be moved using a third finger. Pushing is simple, while drawing requires to use the tip of your finger/thumb to push upwards against the piston head. While convenient, this method will quickly deform both the piston and the cylinder. This isn't the case for syringes which have special built-in rings which allow you to operate the syringe with one hand. A more correct method involves holding the syringe cylinder with one hand, while pushing/pulling the piston using the other hand. If you're drawing fluids too quick, the syringe will draw air instead. Hold the syringe by the tube with one hand and slowly pull the piston with the other. This is very important when drawing viscous fluids as drawing too fast will not draw any liquid, and even crucial with air-sensitive chemicals, where drawing air will decompose the compound. ALWAYS HOLD THE SYRINGE BY THE NEEDLE BASE WHEN DRAWING AIR-SENSITIVE OR PYROPHORIC CHEMICALS! If the needle pops out of the syringe tip, it could spill potentially pyrophoric liquid in your face or you may draw air inside the syringe and ruin the air-sensitive chemical.

Types

Medical

The most common type, medical syringes are transparent, except for the piston which is colored. They come in many volumes, the most common being 0.1 ml, 0.5 ml, 1 ml, 2 ml, 5 ml, 10 ml, 15 ml, 20 ml, 25 ml, 50 ml, 100 ml. Syringe needles tend to be short or medium length.

Glass

Glass syringes are less common than the plastic type, mainly due to their fragility and price. Common glass syringe types include all-glass syringe, where the whole item is made of glass, and glass syringes with a metal piston, usually made of stainless steel.

Metal

Made of stainless steel, this type of syringe is more commonly used in medicine rather than lab.

Needles

Syringe needles consist of a stainless steel hollow tube, sharpened at one end, with the other end being connected to a plastic connector. Medical needles are commonly called hypodermic needles. Some needles are entirely made of stainless steel.

Long or very long needles are commonly used in air-sensitive methods, to transfer air-sensitive or even pyrophoric chemicals from their storage bottles to the reaction flask.

Availability

Syringe and hypodermic needles can be bought from many pharmacies and medical supply stores. Large plastic syringes with all-metal needles can sometimes be found in many hardware and meat stores.

All-glass and all-metal syringes can be bought online or from veterinary suppliers. Lab suppliers will also sell long syringe needles. Veterinary syringe kits tend to contain stainless steel syringes with spare needles and pistons.

Due to their use by drug addicts, some places may not sell medical syringes to the general public without either a prescription or an ID.

Projects

  • Draw and inject fluids
  • Transfer air-sensitive chemicals

Safety

If not properly sterilized, hypodermic needles may contain harmful microorganisms and one (accidental) sting may lead to infection. This isn't much of a problem if the syringes have been used in the chemical lab and haven't been used on living tissue, but problematic if working with biological cultures.

References

Relevant Sciencemadness threads