The Bridge sample needle is a cross-drilled pencil-point needle designed to provide redundant gas input ports located away from the closed needle tip. Hypodermic needles, by contrast, have a single beveled sharp point entry at the needle tip. When used to sample headspace gas, the Bridge needle pierces the overwrap and pulls in sample gas through the two cross-drilled entry ports â€“ providing a minimum of gas restriction while maintaining low needle volume. These ports are perpendicular to the needle surface and located Ä½ inch from the needle tip â€“ providing lowered risk of needle contamination. In the case where one of the ports contacts product or liquid, gas is drawn through the other open port â€“ resulting in no vacuum being produced at the blocked port, and reducing the incidence of needle contamination.
Hypodermic needles are provided in a variety of sizes â€“ with some having substantially larger entry volume, and some having substantially greater gas flow restriction. All of them have sharp bevel cut front entry â€“ which is not only dangerous to the user (needle pricks), but offer no protection from contaminate ingestion. If the needle inadvertently contacts product or liquid, it can easily ingest contamination as it has a single â€“ forward-facing entry port â€“ as they are designed for piercing and liquid delivery or ingestion.