Quick answer: Spare parts and service kits are packed once and used much later, often after time in a warehouse, a service van or a site store room. Put the desiccant in a closed pack: a thin Fiber Desiccant Card in small kits and part bags, a bagged fiber sachet (1 to 1,000 g) in kit cases and bins. Size it on the humidity the parts need and how long they will be stored, then check it each time the kit is opened or re-kitted, using a gentle bend test on cards.
A replacement board, sensor or connector is only useful if it works when the technician opens the kit. Between packing and use, kits can see humid store rooms, hot vans and cold sites. Moisture can corrode contacts, tarnish finishes and damage printed manuals and labels.
Which format for which kit
| Kit or pack | Format | Why |
|---|---|---|
| Single part in a barrier bag | Fiber Desiccant Card, 0.7 or 1.0 mm | Thin enough to lie flat next to a board or module |
| Small service kit or blister tray | Card under the tray or in the lid | Out of the way of the parts |
| Hard kit case | Bagged fiber sachet or a card in a lid pocket | More capacity for a larger air space |
| Storage bin with a sealed lid | Bagged fiber sachet, sized to the bin | Works when the lid seals; otherwise bag the parts first |
| Printed manuals and labels in the kit | Card in the same closed pack | Paper takes up moisture too |
Size for the storage time, not just the trip
The desiccant has to hold the moisture inside the pack at sealing plus everything that gets in over the storage time. Plant-fiber desiccant holds more than 10% of its own weight at 20% RH, and more than 35% at 50% RH and more than 70% at 90% RH at 25 °C. Most parts are sized on the lower-humidity figures. At 1.0 mm thickness, Fiber Desiccant Card absorbs three times as much moisture as silica gel under the same test conditions (25 °C / 90% RH); across 20 to 40% RH on our measured 25 °C curve, plant-fiber desiccant holds about twice as much as silica gel.
Then choose the pack. A barrier bag or a closed case with a good seal lets less moisture in, so the same desiccant lasts longer. An open bin shares its air with the room and the desiccant fills quickly.
Re-kit and check routine
- Each time a kit is opened, check the card: a fresh card feels relatively stiff, and one that has gone noticeably soft has absorbed moisture and should be swapped out
- Replace spent desiccant before the kit is resealed
- Keep opened bags of fresh desiccant within the open-air limits: up to 2 hours at 50% RH or below, up to 1 hour above that, and stop at 80% RH or above; if work pauses for more than 30 minutes, reseal the unused desiccant in a sealed bag
- Keep spare desiccant sealed in its original packaging, cool and dry, oldest MFG date first
- Desiccant keeps 12 months from the manufacturing date, unopened and in the original sealed packaging
A humidity indicator card can show the humidity inside a pack, but it absorbs almost nothing. Use it alongside the desiccant, not instead of it.
Labeling the kit
- Print the card with your part or kit number and a do-not-eat line
- Add a re-kit note to the kit label: check and replace desiccant when resealing
- Keep the desiccant format the same across kits so stores staff know what to stock
Related: 12 places a desiccant card fits, paper desiccant vs fiber desiccant and how to use fiber desiccant.
Frequently asked questions
How long does desiccant protect a spare part?
It depends on the pack, the humidity the part needs and how much moisture gets in. Size for the storage time, use a well-sealed pack and check at each re-kit.
Can a card go in a barrier bag?
Yes. A thin card lies flat beside the part; your QA team decides placement and whether it may touch the part.
What should we use in a large kit case?
A bagged fiber sachet, available from 1 to 1,000 g.
How do technicians know the desiccant is spent?
On a card, gently bend it: a fresh card feels relatively stiff, and one that has gone noticeably soft has absorbed moisture and should be swapped out.
Can you size desiccant for our kit range?
Yes. Send the kit list and pack types and we will suggest formats and send samples.
Size desiccant for your kits
Send us your kit or part list and how it is packed. We will suggest a card or sachet for each and send samples.
Prefer email? info@atmosiscience.com
Figures from ATMOSIScience fiber desiccant product documentation and usage instructions and the Fiber Desiccant Card product sheet.
