Sedative Darts and air Pressure

Most recent answer: 10/22/2007

Q:
I was reading you Q&A’s on air pressure and you had a question on syringes. When a Conservation Officer shoots an animal with a syringe how does the sedative go into the animal without any pressure exerted on the end of the needle? Are there any expearments to show how it works?
- Derek
BlueJay Elementary, Abbotsford, BC Canada
A:
Hi Derek,

I scouted on the web a little bit and found
, of a manufacturer of syringe darts, the kind used by Conservation Officers to tranquilize or vaccinate animals. Look under "General Information" to get schematic diagrams and instructions for use. Don’t try any of this at home unless you are a Conservation Officer.

The long and the short of it is that the syringe is pressurized with air behind the plunger in back of the drug-containing part of the syringe. The needle of the dart is closed on its pointed tip and there are holes on the side of the needle for the drug to flow out (this is so the hole is not closed off if the tip bends on impact). A silicone sleeve is placed around the part of the needle with the holes before the drug is put in the syringe and before the air behind the plunger is pressurized. That way the drug won’t come out while the sleeve is in place. When the needle penetrates the animal’s skin, the sleeve slides back, and the air pressure pushes the drug out.

Tom

(published on 10/22/2007)