Most Common Questions about Humidity Indicators
Humidity causes mold and corrosion. If you take temperature changes into consideration, then condensation can be a problem as well. A desiccant placed in an enclosure only absorbs moisture for a while. Eventually, it loses effectiveness and needs replacing. If you know the level of humidity in a transit case or shipping container, you can take timely action before damage occurs.
This is where humidity indicators come into play. A humidity indicator card is a card on which manufacturers impregnate a moisture-sensitive chemical. Once the humidity outside exceeds the indicated relative humidity, it changes its color to indicate that.
In this article, we’ll try to answer the most common questions about humidity indicators.
What are Humidity Indicators?
Humidity indicators provide an inexpensive solution to indicate or quantify moisture content inside sealed packaging. They’re available in a variety of configurations and materials. They have numerous applications, especially military and semiconductors. The most common humidity indicator cards change color from blue to pink when exposed to humidity levels greater than the indicated RH level.
What are the different kinds of Humidity Indicators?
High Sensitivity Moisture Indicator
This is the most sensitive moisture indicator out there. This is a special manganese-based moisture indicator. It changes color from blue to brown at moisture exposure of 1 ppm. It is Cobalt free!
Gel Silica Indicators
This is another Cobalt free, gel silica indicator. It changes color from yellow to clear when exposed to high levels of water vapor.
CuCl2/Silica Gel Indicator
This indicator has a PH-sensitive dye on silica gel and contains no Cobalt. The Silica gel indicators are able to show moisture from gross leaks in systems that introduce large amounts of water. The color change is from yellow to blue-green. It begins to change color with exposure to 4–6% Relative Humidity.
Indicating Drierite
This indicator contains Cobalt. Europe lists Cobalt as a “Substance of High Concern” in Europe. The indicating Drierite changes color from blue to pink when exposed to 5% Relative Humidity.
A lot of organizations are choosing to move toward a Cobalt Free Indicator like the CuCl2/Silica Gel Indicator to stay in compliance with the EU.
What are Humidity Indicator cards?
A humidity indicator card or HIC is a card that indicates when the indicated relative humidity around it has exceeded a benchmark. A moisture-sensitive chemical is put on such humidity indicator cards and plugs so that it’ll change color when it crosses the indicated relative humidity. Generally, this has been a blotting paper impregnated with cobalt(II) chloride base. But today, less toxic alternatives and cobalt-free humidity indicator cards are available for safe use.
What is a Humidity Indicator plug?
You can screw the Humidity indicator plugs into the walls of containers. These plugs feature a clear window fitted with humidity indicator discs. These plugs can measure interior relative humidity levels and are readable from outside the container. As the interior humidity of the container increases, the discs change in color. Usually, these plugs are made of brass, aluminum, or stainless steel.
What is a Humidity Indicator paper?
You can use Humidity Indicator paper to measure the presence of relative humidity in the atmosphere quickly and economically.
The Humidity Indicator paper is directly exposed to the atmosphere and turns from blue to pink upon contact with relative humidity between 45%-50%. Such paper can help determine the need for dehumidifiers in areas that seem to be high in humidity
How low humidity can Humidity Indicators cards sense?
You can get standard rectangular cards as low as 5% and 8%. Humidity Indicator Plugs can only sense as low as 10%. This is because establishing the color of the card in the plug is more difficult than reading a card that is in your hand. The lower 5% and 8% values are difficult to read due to the small amount of chemical present. This results in a very low-density coloration. Imagine a color to which you add a lot of white to fade the color out.
Why should you use Humidity Indicators?
Moisture can be disastrous for a lot of different types of products. Metal products can rust or corrode and food products can go stale. Mostly, once a product is packaged, it cannot be opened until it is to be used. This is to preserve the integrity of the product.
If you use humidity indicator plugs in the walls of containers, workers can ensure that items are stored at safe humidity levels. This can also prevent their exposure to external elements since humidity levels are checked.
What are some of the lesser-known uses of Humidity Indicator Cards?
There are some uses of humidity indicators that might surprise you. You can find humidity indicator cards in many small electronic devices, from cellular phones to laptop computers. They’re there to alert the manufacturer that the device was exposed to high levels of moisture. In a lot of cases, this voids the warranty or changes the terms of warranty coverage for the concerned device.
For semiconductor packaging, HICs are packed inside a moisture-sensitive bag, along with the desiccant. This helps determine the levels of moisture to which the devices have been subjected. Moisture sensitivity levels are indicated with a number as in the MSL list.
What are irreversible and reversible Humidity Indicators?
Non-reversible or irreversible Humidity Indicators are also known as Maximum Humidity Indicators. Such indicators will not return to the original color once exposed to moisture. They are useful for long-term storage and shipping. They cannot be reused once they’ve absorbed moisture and changed color.
On the other hand, reversible Humidity Indicators return to their original color once exposed to an atmosphere that is dryer than the rating on the card. So, these can be reversed and reused again whenever you need them.
Got more questions about Humidity Indicators? You can let us know in the comments below and we’ll be glad to help you out!
