Syringes utilize a cylinder and plunger for precise delivery of liquids or gases in analytical, medical, pharmaceutical or biotechnology applications.  A syringe is a device used to inject medications or other liquids into body tissues or other media.  A needle is a slender hollow instrument for introducing material into or removing material from the body parenterally.  It is common for syringes to come with needles attached; it is not the rule, however.

Specifying Syringes and Needles

The important parameters when specifying syringes are injection method, needle configuration, syringe volume, syringe scale graduations and pressure rating.  Syringes use one of two injections methods, manual or autosampler.  An injector is a mechanism for accurately injecting a predetermined amount of sample.  The injector can be a simple manual device, or a sophisticated autosampler that permits automated injections of many different samples into the liquid stream for unattended operation.  The needle may have one of two configurations if it is supplied with the syringe.  It may either be removable or fixed.  Syringe volume is the amount of sample the syringe can contain prior to injection.  Syringe scale graduations are the markings printed on the side of the scale for measuring the volume dispensed.  The pressure rating is the maximum pressure the syringe can withstand.

The important parameters when specifying needles are needle gauge, length, inner diameter and outer diameter.  When specifying a needle they range from largest to smallest, the larger the needle’s gauge, the smaller the needle. For example, a 4.0 gauge needle is larger (physical size) then an 8.0 gauge needle.  The important dimensions to consider for needles are length, inner diameter and outer diameter.  The outer diameter is dependent upon the gauge, but this is not true of the inner diameter.

Features common to syringes and needles include replacement needles included with the syringe, interchangeable plungers for the syringes, interchangeable barrels for the syringes, digital display and a Chaney adaptor, which provides a convenient method of performing multiple injections of the same volume of fluid without the need for careful reading of the syringe scale each time.