DESICCANT CLAY SACHETS
Desiccant activated clay sachets are still used in many industries and regions in preference to silica gel sachets.
The adsorption capacity of clay is lower than silica gel, so more is needed to do the same job
e.g. the equivalent of a 25 gram silica gel sachet would be a desiccant clay sachet containing 28 to 33 grams.
This is also known as 1 unit of basic desiccant.
This weight of a Desiccant Unit derives from American and German standards
(MIL-D-3464E and DIN 55473 respectively)
which define the Desiccant Unit as:
‘the quantity of desiccant, as received, which will adsorb at equilibrium with air at 25 degrees Centigrade at least:
(a) 3.00 grams at 20% RH
(b) 6.00 grams at 40% RH'
The lower cost of clay does mean that clay sachets can be cheaper than their silica gel sachet equivalent,
even though more clay is needed to offer the same performance.
Standard size clay sachets include
½ unit (105 x 50 mm)
1 unit (120 x 50 mm)
2 unit (135 x 80 mm)
4 unit (175 x 80 mm)
8 unit (185 x 125 mm)
16 unit (270 x 125 mm)
32 unit (320 x 160 mm)