Desiccant is a dehumidifying agent which attracts moisture from the atmosphere. It adsorbs and holds particles of water to itself. When desiccant becomes soiled or broken down over time, it becomes less effective. Inadequate desiccant can increase energy consumption via lower compression efficiency, air leakage, or pressure variability.
Indicating Color Change Silica Gel
It is a silica gel bead or granule that has been washed with a
concentration of cobalt chloride ( a heavy metal salt). The cobalt
chloride is a deep blue color when it is dry and turns from blue to
purple to pink as it becomes saturated with moisture. Typically, the
color changes as the desiccant goes past 8% moisture levels (by weight)
and indicates it is time to replace the desiccant.
The most typical use for an indicating silica gel is for a moisture sensitive product that will be inspected regularly as it gives a quick visual indication of how well it is doing. Because of the addition of cobalt chloride, indicating silica gel should not be used in contact with products for consumption such as food or pharmaceuticals.
Dew point is a fundamental unit and directly equivalent to water vapor pressure or parts per million. It is a very convenient measure of actual water content of a gas because it is not a function of temperature in the same way relative humidity is.
Knowing the compressed air dew point is critical to many processes. Excessive moisture can result in poor product quality, significant downtime, or corrosion and damage to critical equipment resulting in expensive repairs and lost revenue. To minimize moisture problems, reliable on-line dew point measurement is a must.
Self Testing Desiccant
Before testing, observe the condition of the desiccant. If it looks discolored to a very dark brown or has chips and is turning to dust, these are visual signs of desiccant age. Visual inspection can also be a good indicator for when desiccant is required to be changed.