Hypodermic syringe is commonly used in medical, pharmaceutical and veterinary medicine, used for extracing and injecting fluid and medication. There are two types of hypodermic syringe, 2-part syringe and 3-part syringe. But what’s the difference bewteen 2-part syringe and 3-part syringe?
What is 3-part syringe?
3-part syringe refers to a type of disposable syringe mainly composed by 3 accessories: barrel, plunger and piston. Among which, barrel and plunger is made by injection mould by Polypropylene material, piston is made by injection mould by PVC material or TPE material, or made by vulcanization machine by latex rubber or isoprene rubber or silicone rubber or butyl rubber material. (What’s the difference between syringe pistons made from different materials?)
For 3-part syringe, rubber piston is essential components mainly for two performance.
Firstly, it works for sealing performance. Usually outer diameter of piston will be larger than inner diameter of barrel so that when assembled with plunger and barrel, piston can create a vacuum space in syringe. Also, high elasticiy of piston will ensure less deformation after squeezed by barrel and plunger to avoid air or liquid leakage.
Secondly, with the help of a lubricant (usually silicone oil), piston assembled with plunger can move smoothly in the barrel instead of grabbing the inner side of barrel when sliding up and down.
What is 2-part syringe?
2-part syringe refers to a type of syringe mainly composed by 2 accessories: barrel and plunger, both made from Polypropylene material.
Without gasket part, sealing performance of a 2-part syringe is ensured by pretty precisely designed and slightly oversized plunger head. For this type of syringe, lubricant is no need to ensure sliding performance, that means no extra material is added to make syringe work, thus making 2-part syringe a good substitute for 3-part syringe especially for sensitive application like chromatography, ophthalmics, industrial solvents, paints, glues and various lab use.
- 3-part syringe has one more accessory called piston or gasket to create vacuum space.
- 2-part syringe has much higher standard for plunger head design to create vacuum.
- 3-part syringe will have more material for gasket like PVC, TPE, or Rubber, and lubricant like silicone oil for sliding performance.
- 2-part syringe consists of polypropylene material only.
- 3-part syringe can suit most medical cases.
- 2-part syringe can suit certain sensitive cases like industrial solvents, paints, glues and various lab use which has restriction on extra material like silicone oil.
- 2-part syringe will be more expensive than 3-part syringe.