Alongside silica gels,
we offer a number of related products. Namely: molecular sieves,
clay sachets,humidity indicator cards and paper, desiccant grade activated alumina and
Molecular sieves are
desiccants with differing properties to those of silica gel. With the appearance of small
opaque pinkish beads, molecular sieves are synthetically produced, highly porous
silicates. They have many internal cavities that are linked by window openings of precise
diameters. It is
these diameters (measured in ┼ngstroms) that classify molecular sieves - 3┼,
4┼, 5┼, and 10┼ (also known
as 13X). Adsorption occurs only of molecules with smaller diameters than
these cavity openings. Larger
molecules will be excluded from adsorption. Preferentially adsorbed are molecules of
This makes molecular sieves ideal for adsorption of water from air and liquids, as
water molecules are
both polar and very small. Molecular sieves will adsorb water molecules and other
from liquids and gases down to very low levels - often just 1 part per million.
Examples of the applications of the differing molecular sieve grades are :
Grade 3┼. Dries unsaturated gases and organic liquids (e.g methanol).
Used to remove water from cleaning fluids in ultrasonic baths.
Grade 4┼. Is a general dryer of liquids, natural gases. Also an
excellent adsorber of carbon dioxide.
Grade 10┼ (13X). Is used in air prepurification (due to its high water
and carbon dioxide adsorption capacity)
and also adsorbs sulphur compounds ('sweetens'). It will remove decomposition products
the quenching of arcing in electrical products.
Molecular sieves properties as desiccants differ from silica gel in a
number of ways :
(1) They adsorb water vapour more rapidly than silica gel.
(2) They will reduce water vapour to much lower levels than silica gel, making their
when a very dry product or atmosphere is required.
(3) They perform more effectively as moisture adsorbers at higher temperatures
(greater than 25░C) than silica gel does.
of grades 3┼, 4┼ and 10┼ (13X) are stock items.
They are sub-classified by their bead sizes, typically 1.6 - 2.5 mm
and 2.5 - 5.0 mm.
They are available in the same bulk pack sizes as silica gel - 500 gram or 1 kg in
polytubs or foil packs.
3 kg and 10 kg in polytubs. 25 kg, 130 kg and 150 kg in metal drums.
Molecular sieve sachets are supplied to customers requirements. They can
be made with any of the
grades mentioned, in most sachets from 3 gram to 500 gram and above.
These are high performance,
high capacity calcium chloride based desiccant products
that are specifically designed for use in shipping containers.
Each pole has the capacity to collect up to 2,000 grams of moisture,
4 to 6 poles are enough to protect a 20 foot container through an entire voyage.
The 750 mm long poles are designed to fit in the recesses of the container,
the water collected remains fully contained and the used pole can be disposed of as
Please e-mail/phone for further details and prices.
DESICCANT CLAY SACHETS
clay sachets are still used in many industries and regions in preference to
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 30 to 33 grams.
This is also known as 1 unit of basic desiccant).
The lower cost of clay though does mean that overall costs can be similar between both
Clay sachets are often made to order, including 'unit' sachets - 1 unit, 2 units,
4 units, 8 units and 16 units.
INDICATOR CARDS AND PAPER
The actual moisture content of
air within a package expressed as a percentage of its saturation moisture
content, is termed the Relative Humidity (RH). The crucial factor in preventing corrosion
growth to stored or in transit items, is to keep the RH below 40 to 50%. Carefully
calculated, the use
of silica gel sachets will keep the RH below this level. This can be confirmed
by the use
of humidity indicator cards or papers which give a guide to the RH level.
We currently offer the following humidity indicators :
(1) Six Spot Indicator Cards (10 - 60%)
Each spot represents a RH level from 10 - 60%.
The higher up the card
the spots change from blue to pink, the higher the RH. This allows an accurate reading of
humidity level and again, aids in indicating when silica gel sachets require replacing.
or Four Spot Indicator Cards
Similar to six spot cards, but with each spot representing a RH level:
5 - 10 - 60%
10 - 20 - 30%
30 - 40 - 50%
10 - 20 - 30 - 40%
(3) Safe/Unsafe (One Spot)
Cards or Paper
The paper will change colour dependent on the RH level. A pink paper indicates that the
silica gel sachets
need changing to prevent moisture damage occurring. A blue paper indicates that the
RH is at safe levels.
Similarly, the indicator card has a spot that changes colour in the same fashion.
This can be compared to a blue fixed colour on the card - if the spot
shows the same colour or a darker blue than the fixed panel, then the RH is at safe
A pinker colour and the RH is considered unsafe.
All of the humidity indicator cards and papers are sold in small or large quantities.
Desiccant grade activated
alumina is a highly porous form of aluminium oxide. It has the appearance
of white chalky beads. Standard stock sizes have 2 - 5 mm or 5 - 8 mm beads.
1.2 - 2.4 mm beads are also sometimes available.
An adsorbent from liquids and gases, it is supplied to customers requirements, usually in
A granular coconut shell carbon
suitable for various air and water treatments (including diving
equipment applications) is available from stock - packed in 2.5kg, 7.5kg and 15kg
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