e-Gel indicating silica gel is used in many applications; however its primary function is to adsorb moisture.
The word adsorb has a different meaning to absorb.
Adsorb is to hold molecules on the outside of the structure – in this case the SiO2 – not taken “inside” the body of the SiO2, which would be absorbing.
One of the most common uses of silica gel is in the electrical industry, specifically in moisture control for transformers. In this application there are bottles or chambers, commonly known as breathers.
These breathers are plumbed in, to dry out the air that is sucked in from atmosphere into the transformer line. When the air passes through the breathers the e-gel that is filling the breather adsorbs the moisture form the air, so that when the air reaches the transformer line, the air is sufficiently dry.
There are options for the configuration of the breathers, such as:
disposable (these are simply unscrewed from the “tranny” line and a new one screwed in to place);
Refillable breathers, (these are units that the spent gel can be emptied out of, then the breather can be re-charged with new/regenerated e-Gel);
Certain breathers are designed with an oil bath;
Certain other breathers have valves in their base, to to control the flow of air in and out of the breathers.
Another popular use for e-Gel s in packaging of product so as to ensure suitability in storage and transport. Omni-tuff has a number of different size e-Gel sachets, and these are typically used as a moisture controller in palletised or other gear.
So, if you have gear being stored for a substantial period of time and the items are potentially going to be damaged if there is any moisture ingress, look at the Omni-tuff e-Gel sachets. As a rough rule of thumb allow 1 kg of e-Gel for 1 cubic metre and this will last between 6and 12 months.
The good part about e-Gel is that there is a definite colour change, from orange to green; when you see green, it’s time to change the gel!
A common question as to e-Gel is whether the customer is allowed to re-generate and re-use the e-Gel. Many sites do re-use e-Gel a second or third time. The end-user uses a drying process, such as the Omni-tuff Hopper Dryer. 25kg of e-Gel will take approximately 4 hours to dry at 100⁰C to 120⁰C.
Every time you regenerate e-Gel, approximately 20% of the pores in the gel molecules will not re-open so that the drying ability will decrease each time you choose to regenerate the e-Gel.
When the e-Gel is new it is orange, and once it is spent, it is dark green. When you re-generate the gel, it does change back to orange., however not always as bright as the original unspent colour.
As many would have already had experience, other applications for silica gel is for items of clothing, such as shoes and other footwear; also medical industry uses gel and other desiccants for keeping tablets absolutely dry.