The dry bulb and wet bulb are nothing more than a probe used to measure temperature, the probes can consist of various types, shapes, sizes, and materials although the most common probe used in the meat processing industry is a stainless steel 100Ω Platinum 3 wire probe.
In an oven the dry bulb measures the ambient temperature of the oven, the probes can be located in the discharge air stream or in the return plenum depending on the oven type and design.
The wet bulb consist of four parts
1. Typical 100Ω Platinum 3 wire RTD
2. Wet sock – must be clean absorbent 100% cotton
3. Psychrometer Pan
The psychrometer pan in most cases will support the wet bulb and dry bulb, the wet bulb probe mounts over the pan portion with the water. The wet sock should slide over the probe and hang partially submerged in the pan of water. The purpose of the wet bulb is to give an indication of the amount of moisture in the air, this is done by evaporation as dry air blows across the wet bulb probe the wet sock gives off moisture which creates an effect known as evaporative cooling this cooling effect becomes greater with dryer air.
The dry bulb and wet bulb can also be used together to calculate relative humidity.