A 95 kPa specimen bag is a transport bag rated to hold a 95 kilopascal pressure differential without leaking, which is the pressure test required for the secondary packaging in a UN3373 Category B shipment. The number comes from Packing Instruction 650, the rule set for shipping diagnostic specimens that are not in Category A. In practice, the bag is one layer of a three-part system, and knowing which layer does what is what keeps a shipment compliant.
What does 95 kPa mean on a specimen bag?
It is a pressure specification. The secondary packaging must withstand an internal pressure differential of at least 95 kPa without leaking, so that if a specimen leaks or the aircraft cabin pressure changes, the packaging holds. The test is a design requirement of the packaging, not a property of the specimen. When a bag is described as 95 kPa certified, it means the manufacturer has tested that bag design to the pressure requirement in Packing Instruction 650.
What is UN3373 and when does it apply?
UN3373 is the UN marking for Biological Substance, Category B, covering diagnostic specimens that are infectious but not on the high-risk Category A list. Category B shipments travel under Packing Instruction 650, which sets out the three-layer packaging, the absorbent requirement, the 95 kPa pressure test, and the outer marking. If a specimen is a Category A infectious substance, it falls under a different instruction and a different label, and a 95 kPa bag alone does not cover it.
What are the three layers of P650 packaging?
| Layer | Requirement | What fails if it is skipped |
|---|---|---|
| Primary receptacle | Leakproof, holds the specimen | A leak contaminates the outer layers |
| Secondary packaging | 95 kPa pressure rating, with absorbent material | No pressure protection and no spill control |
| Outer packaging | Rigid, with the UN3373 diamond marking and correct labelling | The shipment is mislabelled and can be refused |
Do 95 kPa bags make a shipment compliant on their own?
No. The bag is the secondary layer, and compliance depends on the whole assembly. You still need a leakproof primary receptacle, enough absorbent to soak the full volume of the primary containers, a rigid outer box that protects the bag, and the correct UN3373 marking and documentation. A bag sold as 95 kPa certified is a component that helps you meet the requirement, not the requirement itself.
How do 95 kPa bags compare with 3-wall transport bags?
A 3-wall transport bag typically combines an absorbent layer and a documentation pocket in a single pouch, which reduces the number of separate parts a courier has to assemble. A 95 kPa bag focuses on the pressure-rated secondary layer. Many clinics use a 3-wall format for routine specimens because it is faster to pack, and a pressure-rated 95 kPa bag where the workflow or the courier calls for the specific pressure specification. The 12 by 15 inch 95 kPa specimen bag, 100-pack and the 6 by 9 inch 3-wall transport bag, 100-pack cover both approaches.
What should a clinic record when preparing a Category B shipment?
Keep a simple transport record for every dispatch: the date, the number of primary containers, the absorbent used, the outer packaging type, and the courier reference. Note the required transport temperature for each specimen, since some assays need refrigeration and others are stable at ambient, and confirm the cold pack or dry ice arrangement before the bag is sealed. The record is what lets a clinic show, after the fact, that a shipment was packed to Packing Instruction 650 rather than reconstructed from memory during a review.
Clinics that want the paperwork side handled for them can print the printable sterilization log, run the clinic supply planner, or talk to a sterilization compliance specialist. Buying for a multi-site group? Wholesale ordering covers case and pallet volumes, and the BI 5-pack trial (CA $12.99, shipping included) is the low-commitment way to test monitoring consumables first. Reselling? become a distributor.
Related Reading
- Specimen container types
- 95 kPa specimen bags: choosing UN3373 Category B packaging
- 95 kPa specimen bags vs 3-wall transport bags
- 95 kPa specimen bags, 12 by 15 inch, 100-pack
Frequently Asked Questions
What does 95 kPa mean on a specimen bag?
It is the pressure differential the secondary packaging must withstand without leaking, as required by Packing Instruction 650 for UN3373 Category B shipments.
Is a 95 kPa bag enough for UN3373 transport?
No. It is the secondary layer, so you also need a leakproof primary receptacle, absorbent material, a rigid outer box, and the correct UN3373 marking and paperwork.
What is the difference between a 95 kPa bag and a 3-wall bag?
A 95 kPa bag is built to a pressure rating, while a 3-wall bag combines an absorbent layer and a document pocket for faster routine packing at the bench.
When does UN3373 not apply?
UN3373 covers Category B diagnostic specimens. High-risk Category A infectious substances fall under a different packing instruction and a different label.
Last updated: October 2026. CliniEco Medical is a licensed medical device establishment (MDEL #35334).
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