There are a few simple methods, for your reference:
1) silica gel desiccant bags ripped, take silicone silicone materials holding hands, see if there is fever, heat dissipation is silica gel desiccant is valid.
2) add blue plastic, Orange gel indicator, indicates that the rubber has color, indicating silica gel has been voided.
3) containing small cup of cold water, tearing the bags, the raw materials into the water, see if the silicone beads will be blown to bits, and issued a "scrape" sound, is that effective.
4) small bags of silica gel desiccant, good weight, label placed inside every 5-10 day weigh, weight will increase, increasing the effective.
5) If you want to know the exact moisture absorption of silica gel desiccant performance required for laboratory equipment.