FAQ

This is a great question!

In the past this has created a lot of confusion so to clear the air our purpose built controls have the names like PC5000 and PC6000 which might lead one to think the “PC” is referring to a PC or personal computer like you would have at home but this is not the case at all, the “PC” is actually an acronym taken from our company name Powis Corporation, what? That’s crazy you say!

Well for those of you crushed by the news that your control is not a personal computer then just think of it as a PLC or programmable logic controller preconfigured to control your smoke house or chiller.

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.

Dry Bulb
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.

Wet Bulb
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

4. Water

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.

Supply air regulator typically set to 25 psi.

Dry Bulb Heat Sources
Gas burner actuator operates between 3-15 psi (3 psi = closed, 15 psi = full open)
Steam coil valve operates between 3-15 psi (3 psi = closed, 15 psi = full open)
Steam cook valve operates between 3-15 psi (3 psi = closed, 15 psi = full open)

Wet Bulb Heat Sources
Fresh air and exhaust dampers are typically controlled form the same air source and operate between 3-8 psi (3 psi = open, 8 psi = closed)
Humidity valve operates between 9-15 psi (9 psi = closed, 15 psi = full open)

Plant Matrix was developed to answer the need of a real-time inventory tracking software in the meat processing industry. This growingly daunting task, long done manually, has been the source of years of research and development for Powis Corporation. Plant Matrix is the result of this hard work, and was built with the knowledge of over 25 years in the industry and with help from suggestions from our hundreds of customers.