BULK SILICA GEL
Whilst most frequently used in sachets, silica gel has a number
of applications in its loose form.
These include use in transformer and breather units, in desiccators,
for dynamic adsorption processes and for drying flowers.
There are different grades of silica gel – non-indicating (white)
and three self-indicating types
(orange to green, orange to colourless and blue to pink).
There are two physical forms of the silica gel, bead (uniform spheres)
or granular (irregular crystals), which are further sub-classified
by the diameter of their particles.
Non-indicating (white) silica gel
2 – 5 mm and 1 – 3 mm bead.
0.2 – 0.5 mm, 0.5 – 1.0 mm
and 3 – 6 mm granular
Standard white, non-indicating silica gels offer the highest weight for weight moisture adsorption capacity.
The beaded non-indicating silica gels conform to BS 7554:1992
The granular non-indicating silica gels conform
to BS 2540:1991
Self-indicating silica gel
(orange to
dark green)
2 – 5 mm and 4 – 8 mm bead and 0.5 – 1.0 mm granular
Using an organic indicator this silica gel offers a very strong orange (dry) to dark green (near exhausted) colour change.
It is mostly used in the low dusting, beaded forms.
All self-indicating silica gels
are sold in bulk
(or can be packed into sachets).
Self-indicating silica gel
(orange to colourless)
2 – 5 mm bead.
1 – 3 mm and 3 – 6 mm granular
Using iron salts as the additive, this high capacity desiccant changes from a deep orange (dry) to a very pale yellow colour in an exhausted state. The indicator is very robust, making this silica gel well suited to repeated regeneration and reuse.
Available in both granular and beaded physical forms.
Both orange self-indicating silica gels are non-toxic materials developed following the re-classification of blue to pink self-indicating silica gel as a toxic material, in the year 2000.
Self-indicating silica gel
(blue to pink)
2 – 5 mm bead
Changing from blue (dry) to pink in it’s near-exhausted state and still popular in many regions and industries, it is the cobalt in the cobalt chloride indicator that is responsible for the toxic labelling and disposal restrictions on this grade of silica gel.
It still though remains, not regulated as dangerous goods for transportation purposes.
This silica gel conforms
to BS 7554:1992
Pack Sizes
We offer the silica gels packed in a range of standard size foils, tubs, tins and drums.
All granular silica gels
With a lower bulk density (~ 650 to 700 grams per litre), these pack
- 500 gram and 1 kg plastic containers or sealed foil bags
- 3 kg poly-tins and 10 kg poly-tubs
- 25 kg steel drums, cardboard kegs and poly-sacks
- 140 kg steel drums
All beaded silica gels
With a higher bulk density (~ 750 to 800 grams per litre), these pack
- 500 gram and 1 kg plastic containers or sealed foil bags
- 3 kg and 4 kg poly-tins and 12½ kg poly-tubs
- 25 kg steel drums, cardboard kegs and poly-sacks
- 150 kg steel drums and 800 kg big bags
Uses
Fine granular silica gels (0.2 – 0.5 mm or 0.5 – 1.0 mm)
are suitable for drying flowers.
Dynamic adsorption processes often require a large silica gel (2 – 5 mm bead or 3 – 6 mm granular) that allows air to be passed through them.
For desiccator units, medium silica gels
(1 – 3 mm or 2 – 5 mm) are preferred.
When considering a volume to be filled, approximately 650-800 grams
of silica gel occupies 1 litre of space, with granular silica gels at the
lower end of the range and beaded materials at the higher.
All packaging types are sold in singles or multiples.
Unit prices fall as volumes rise.
We are also able to sell silica gel in other non-standard size packs, according to customer’s requirements.
These foils, tins and drums can also be custom labelled as requested.
Advantages of silica gel as a desiccant
Silica gel has many properties that recommend it as a desiccant.
It will adsorb up to 40% of its own weight in water vapour.
This adsorption efficiency is approximately 35% greater than
typical desiccant clay, making silica gel the preferred choice
where weight or efficiency are important factors.
It has an almost indefinite shelf life if stored in airtight conditions.
Most grades can be regenerated and reused if required. Gently heating silica gel will drive off the adsorbed moisture and leave it ready for reuse.
It is a very inert material, it will not normally attack or corrode
other materials and with the exception of strong alkalis
and hydrofluoric acid, it is itself resistant to attack.
It is non-flammable.
It is most frequently and conveniently used packed in a
breathable sachet or bag. These are available in a wide range of sizes suitable for use with a wide range of applications.