What is a 95 kPa specimen bag and when do I need one?

A 95 kPa bag is a pressure-rated secondary package designed to withstand a pressure differential of at least 95 kilopascals, which is the condition that occurs when a sample that is being moved by air is exposed to cabin depressurisation or a change in altitude. It is the secondary packaging specified for transporting Category B biological substances under UN3373, and it must be leakproof, watertight and re-closable. You need one whenever a diagnostic specimen leaves your premises by air, courier or third-party logistics service. If your samples only move between rooms in the same building, a plain zip-lock specimen bag with a document pouch is normally sufficient.

How much absorbent material should a transport package contain?

The absorbent material must be able to absorb the entire volume of the primary container, so that if the tube or bottle leaks there is no free liquid loose inside the package. As a working rule, allow at least one gram of absorbent for every millilitre of liquid being carried, and place the absorbent directly under and around the primary container inside the secondary bag. Do not count the padding towards absorbency unless it is explicitly absorbent. If you ship several containers in one bag, size the absorbent for the total combined volume, not for one container.

Where should I place the request form or paperwork?

Always in the separate document pouch on the outside of the bag, never inside the bag with the specimen. This is the whole point of the pouch: if the primary container leaks, the paperwork stays clean and readable, and anyone handling the bag is not exposed to contaminated paper. Check that the pouch is on the outside face of the bag, that the form is fully inserted, and that the pouch flap is closed before the bag is sealed. Write the patient or sample identifier on the primary container and on the form, not on the bag itself.

What does JWRESEARCH supply for sample transport in Singapore?

JWRESEARCH supplies specimen transport bags in Singapore including plain zip-lock bags, bags with built-in document pouches, 95 kPa UN3373 secondary packaging, absorbent pads, sterile sampling and stomacher bags, tamper-evident security bags and biohazard autoclave bags in the standard red and yellow colours. We stock a range of sizes so a single order can cover blood tubes, urine containers, swab tubes, food samples and environmental swabs. Send us your sample type, container size and the way the sample travels, and we will match the bag, absorbent and closure that keep your shipments compliant and leak-free.

Sample Transport Bags and Specimen Bags Singapore

Published: {{NEW_ARTICLE_DATE}} | By JWRESEARCH | Category: Laboratory Consumables

A sample bag looks like the least technical item in the laboratory, which is exactly why it gets the least attention, right up to the day a leaking tube ruins a transport batch or a courier refuses the package. Bags do three jobs at once: they contain a spill if the primary container fails, they separate dirty paperwork from clean paperwork, and they tell the handler at a glance whether the contents are routine or infectious.

At JW RESEARCH SUPPLY, we supply specimen transport bags and sample bags to clinical, food, environmental and research laboratories across Singapore. This guide covers the bag families, the materials and pressure ratings behind them, and how to match absorbency to the volume you are moving.

Why the Bag Is Part of the Test

The primary container protects the sample; the secondary package protects the people and the paperwork around it. That distinction decides how a bag is specified. A specimen bag with an integral document pouch keeps the request form readable even if the tube has leaked, because the form lives in a pocket on the outside of the bag. A pressure-rated bag adds a leakproof, watertight construction that survives a 95 kPa differential, the standard applied to Category B biological substances moved as UN3373. A biohazard bag does the opposite job: it holds used material on its way to the autoclave and is designed to be opened only in a controlled place.

Bag Types Compared

Type	Typical Use	Closure	Notes
Plain specimen bag	In-house sample movement	Zip-lock	Economical, clear film, no pouch
Specimen bag with document pouch	Clinical and diagnostic transport	Zip-lock with outer pouch	Keeps request forms separate from the sample
95 kPa pressure bag	UN3373 Category B by air or courier	Zip-lock or press-seal	Pressure rated, used as secondary packaging
Sterile sampling bag	Food, water, environmental swabs	Wire or zip closure	Supplied sterile, often used in stomachers
Tamper-evident bag	Chain-of-custody and security samples	Seal with permanent closure	Shows clearly if the bag has been opened
Biohazard autoclave bag	Waste and used consumables	Twist-tie or drawstring	Red or yellow film, autoclave compatible

Specification Reference

Parameter	Typical Value	How It Is Used
Material	LDPE, LLDPE or PP film	LDPE for flexibility, PP for clarity and stiffness
Thickness	40 µm to 100 µm	Thicker film resists puncture from tube caps
Bag size	150 × 230 mm up to 300 × 400 mm	Size to the container, not to the label
Pressure rating	95 kPa minimum for UN3373 secondary packaging	Required for air transport of Category B samples
Temperature range	−20 °C to +60 °C for standard film	Confirm before freezing or warm transport
Sterility	Non-sterile or EO sterilised	Sterile bags for direct sampling and microbiology
Document pouch	Integral outer pocket	Holds the form away from the specimen
Pack format	100 to 1,000 per pack	Buy in the pack size your bench consumes weekly

Matching Absorbency to Volume

Absorbency is the number most often got wrong. The absorbent inside the bag must be able to take up the whole volume of the primary container, so that a broken tube produces a soaked pad rather than a pool of liquid sliding around inside the package. A useful working rule is one gram of absorbent per millilitre of liquid, placed under and around the tube. Where several containers travel together, size the absorbent for the total volume. Padding material only counts if it is genuinely absorbent, and a bag that is full to the seal cannot be closed properly, so leave room for the absorbent and the pouch.

Handling and Labelling

Label the primary container, not the bag; the bag is packaging, not the record.
Seal the bag at the bench, before the sample leaves the work area.
Keep request forms in the outer pouch with the identifier facing the window.
Never re-use a transport bag, even if it looks clean.
Do not overfill: the closure must seal flat with no film trapped in the track.
For air transport, use a rigid outer box and confirm the whole package meets UN3373 packing instructions.

Ordering Checklist

Sample type and container size, including the largest tube you routinely ship
Whether paperwork must travel with the sample, and whether a pouch is needed
Transport mode: internal, road courier or air, which decides the pressure rating
Sterility requirement for sampling and microbiology bags
Absorbent pads sized to the total liquid volume
Disposal route, so biohazard and autoclave bags match the waste policy

Send us your container sizes and a short description of how the sample travels, and we will match the bag, absorbent and closure that keep your shipments compliant and leak-free, with local delivery across Singapore.

Contact JWRESEARCH

JW RESEARCH SUPPLY — laboratory equipment and consumables, Singapore.
Telephone / WhatsApp: +65 8039 3660
Email: SINGAPORE@JWSHY.COM
Website: www.jwresearch.cn