Frequently Asked Questions including How Dry does it get Indoors in the Winter ?

Dry or Winter Air is Hazardous to Empty Capsule Storage & Filling

Quick and Clean Humidity Control

Quick Facts about Humidity Gauges

What is Humidity ?

Drier than the Sahara! Yes, outside winter air heated to room temperature is drier than desert air! For example, outside air, at a temperature of 35^oF (1C) and RH of 70% (typical winter conditions) when heated to 70^oF (21C) would have a RH of 20% - well below the recommended conditions for storing and filling empty capsules.

If the outside air were a mild 50^oF (10C) and had an RH of 60% when heated to 70^oF (21C), it would have an RH of 30% - this too well below the recommended conditions for storing and filling empty capsules. For an explanation of why this occurs, click "What is Humidity?"

Low Relative Humidity is still a problem during winter months as research has found that well insulated, tightly constructed buildings undergo about one complete air change per hour. Thus, you need to continuously add moisture to compensate for the moisture absorbed by the air being brought in.

There is no place in the continental US that does not have a low Relative Humidity problem during part of the year, especially in winter, if room conditions are maintained at 70°F.

Low relative humidity can appear as occasional customer complaints of capsule breakage or brittleness many months after filling. This is because the initial loss of moisture from the shell is not sufficient to cause capsule breakage. However, additional losses in moisture during subsequent handling may cause a problem. It is very important to understand that capsules are particularly sensitive to Relative Humidity when they are unfilled. This is because the walls are unsupported and there is a tremendous volume of air contained inside the capsule that can extract or release moisture from the capsule walls. Once the capsule is filled, the walls are supported and the air inside the capsule is essentially eliminated. Thus, the sensitivity of capsules to environmental conditions is reduced. For more information ask for our bulletin Seven Steps to Success in Capsules.

We all know that dry winter air is a major cause of sore throats, chapped lips, static electricity and dry skin. Dry winter air is also hazardous to the smooth operation of your capsule filling department. This bulletin will help you prevent problems due to dry winter air.

Capsules are shipped with 13-15% moisture content. It is important that this moisture content be maintained year-round. During winter months heating results in a drop in the relative humidity. Empty capsules exposed to dry air rapidly lose moisture and become brittle and shrink in size.

To prevent moisture loss, the air where capsules are stored should have a Relative Humidity between 40-60%, which, fortunately, is the ideal breathing conditions for humans. And, the air where the capsules are filled should have a Relative Humidity between 45-55%. For a definition of Relative Humidity see box on reverse "What is Humidity". Note: Capsules should be stored at a temperature between 60 -750° F (15 - 25C).

If you are filling capsules in a small room (20 ft. x 20 ft.), we would recommend a steam humidifier with a humidistat control (available at a local hardware store) with the air jet directed away from capsules (empty, packed or stored). It is important to direct the air jet away from capsules to prevent heating/cooling the capsules, and of course, over humidifying the capsules. If you use a "cold" (water wick or ultrasonic) humidifiers there is less risk of bacterial contamination of the air so use a anti bacterial additive regularly. We use water wick humidifiers (made by Bemis Mfg., www.bemismfg.com Tel. 414-467-4621).

Accurate humidity measuring devices are not available at your local supermarket or drug store. Nor do they cost less than $50. We recommend the following gauges which are accurate to +/- 5% RH available from Torpac directly or from Cole-Parmer (www.coleparmer.com):

Temperature Humidity Digital Type Indicator (Cole-Parmer Model EW-03313-86), $60.00.

Temperature/ Humidity Chart Recorder (Cole-Parmer Model EW-80055-00), $495.00.

Humidity is defined as the amount of water vapor in air. Absolute humidity is a measurement of the actual water in a given volume of air, usually expressed in grains of water per cubic foot or pound of air.

Relative Humidity (or RH) is the amount of water vapor held in a given volume of air at a given temperature, expressed as a percentage of the maximum amount of water (100% RH) that can be held in the same amount of air at the same temperature.

Since air expands as it is heated, it will hold more Water vapor as it approaches saturation. When a volume of air at a known %RH is heated, the %RH decreases as the volume of air increases. The absolute humidity or total moisture available in the air remains the same. To increase the %RH of the air once it has been heated, it is necessary to add moisture.

Example: One cubic foot of air at 0^oF holds 0.48 grains of water at saturation. One cubic foot of air at 70^oF holds 8.10 grains of water at saturation. When the 0^oF is heated to 70^oF, the absolute humidity remains at 0.48 grains per cubic foot. The relative humidity of the 70^oF air will be 6% RH,