Dehumidifier Longevity

[HenryFan]

Does anyone have knowledge of safe dehumidifier longevity? Specifically, I refer to the silica gel packs that are heated in an oven to recharge them for continued use. Is the media (it says Silica Gel on the box) effective for years or for decades?

I ask because I use them in my safes and today I heated them in the oven. I realized that the oldest of the three boxes probably approaches twenty years plus in age. Many reheating cycles involved.

Does efficiency wane with age?

[Mags]

Google returned this...

A "rechargeable" dehumidifier pack, typically made with silica gel, can last for a very long time, essentially a "lifetime" when properly cared for, as it can be recharged hundreds of times by placing it in an oven to remove absorbed moisture, allowing for continuous use over many years.
Key points about rechargeable dehumidifier packs:

No set expiry date:
Unlike disposable packs, they don't have a fixed lifespan as long as they are properly recharged when saturated.

Indicator for recharging:
Most packs have a color-changing indicator that shows when it's time to be recharged.

[HenryFan]

Mags -

Thank you.

That answers my questions.

[rickhem]

I spent much of my working life in pharma development, working in laboratories. We used to use a color indicating silica gel in our desiccators. These are small chambers where we'd store the very small bottles of standards and some other critical materials that didn't require any low temperature storage conditions. There were a few other lab instruments and equipment that also used silica gel to keep the %RH (relative humidity) as low as possible. We also had an oven that we used to dry glassware, and that oven was kept at a constant 60ºC. Whenever there was any question about the status of the silica gel, or whenever the little indicators on the desiccators showed that the internal reading changed a bit, we'd just take the silica gel and move it into the drying oven for a couple hours, then put it back into wherever it came from. We had a big 1-gallon size jar with fresh silica gel in our cabinet, but in years and years, we never needed to use any.
I'd say that you're fine with periodic drying, and just putting it back. It's amazingly stable, and the drying cycles don't hurt it at all.

[HenryFan]

Rick - Thank you.