![]() Weigh the gel every two to three days until its weight has stopped changing. If the gel is exposed to the desired relative humidity, it can be weighed until its weight stabilizes, indicating that it has reached an equilibrium state with the relative humidity in the control chamber.Because silica gels may vary among manufacturers, this calibration chart will be specific to the brand and type of gel used in the calculations. By doing this, you will have a record of the weights of the silica gel at different humidity levels. (Note: Saturated salt solutions can be used) When the desired humidity level has been reached, record the weight on the chart. Slowly continue to raise the humidity and record the weight at each increase of 10%. Once the gel reaches the appropriate weight, the desired moisture content has been achieved.Įxample: Expose a known quantity of silica gel (2 cups) in an environment of 20% relative humidity and record its weight. If the gel does not come with a chart, you can create your own using the technique outlined below. Many silica gel product come with a calibration chart giving weight relative to humidity level. The weight of a known quantity of silica gel relates to its moisture content.Weighing the gel: There are actually two different techniques that rely on the weight of the gel This can be done in two ways: by weighing the gel or by monitoring the air surrounding the gel. In order for the gel to be conditioned successfully, its moisture content must be monitored. How is the moisture content of the silica gel determined? In some instances, the gel can be sent back to the manufacturer for reconditioning. Purchasing preconditioned silica gel is convenient, especially if you lack conditioning equipment, but is more expensive than buying unconditioned silica gel. The manufacturer is told the percentage of humidity that is desired. A few companies, however, do sell preconditioned silica gel ready for initial use. Most silica gel is shipped in a desiccated state. ![]() Is preconditioned silica gel available for purchase? Moisture is added to the atmosphere of the dry gel until the desired moisture content of the case environment is achieved. Adjusting up: Silica gel used in any capacity other than desiccation usually needs to be adjusted upwards.Silica gel used as a desiccant will need to be dried completely-as close as possible to zero humidity- by heating the gel in an oven, as described in more detail below. Adjusting down: Although dry silica gel is assumed to be just that, it usually contains a small percentage of water.In the field, silica gel moisture has even been removed by exposure to the sun on a dry day. 1 A slow but effective method used in many institutions over the years involves exposing the gel to the air of a controlled room, space or chamber which has the desired RH. Adjusting silica gel involves either removing or adding water to the gel in a controlled way. To humidify or add moisture to the air, the silica gel may need to be adjusted up. To absorb moisture, thus drying out the case air, the gel may need to be adjusted down. What is meant by conditioning and reconditioning silica gel? Īfter the gel type and quantity are selected, the gel must be conditioned to the particular requirements of the case environment. Over time, the gel may require reconditioning. Silica gel must be conditioned to the desired relative humidity before placement inside an exhibit case. 5 Products, Manufacturers, and Suppliers.4 What methods can be used to condition silica gel?.3 How is the moisture content of the silica gel determined?.2 Is preconditioned silica gel available for purchase?.1 What is meant by conditioning and reconditioning silica gel?.
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