Fundamentally, High Pressure Fans are used in:
- High resistance systems
- Systems in which the fans must have sufficient negative pressure or positive pressure build-up at lower power and speed
1. Overcoming high resistance
In most pig barns, each section has its own ventilation system, which provides minimum and maximum ventilation. With a standard ventilation system, the resistance ∆ P Stat to be overcome in the barn can be around 40 Pa and rise to at least 80 Pa (depending on the system). For such systems, we use a standard range of Axial Fans. Examples of this type of fan are Panel Fans and Tube Mounting Fans. There are, however, systems where, among others, air washers, heat exchangers and air filters cause the negative pressure or positive pressure (∆ P Stat) to be overcome to rise well above 80 Pa. For these applications, we use High Pressure Fans.
2. Stable negative pressure when regulating fan speed
As the conditions inside and outside a barn change daily, a ventilation system must be flexible. In addition, growing pigs are also a changing factor. This means that the amount of air must be variable. It is important to dissipate heat, moisture and ammonia, but primarily to supply oxygen. One of the characteristics of High Pressure Fans is that even when the fan speed is adjusted, they still provide an acceptable pressure build-up. As previously explained in our blog, The fan laws, we see that when regulating the fan speed, the flow (M3/h) is linear and the pressure ∆ P Stat (Pa) decreases quadratically while the power consumption (Watt) even decreases to the 3rd power.
Example:
At full speed and a ∆P Stat of 50 Pa, our High Pressure Fan H6D82C0M10100 delivers approx. 26500m3/h with a maximum ∆Stat of 200 Pa and 19100 m3/h. The power consumption in this case is 2850 Watt.
At half speed this becomes (50/100) *19100 m3/h =9600 m3/h at a ∆ P Stat of (50/100) ^2*200 =
+/- 50Pa. The power consumption then drops to (50/100) ^3 *2850 = 356 Watt (excluding controller losses).
In other words: To be able to create a reasonable pressure at low speeds, the fan must deliver high pressure at 100% speed.
3. Essential for central exhaust systems and air washers
Pig barns often use central exhaust systems and air washers. With these types of ventilation systems, High Pressure Fans are used for a stable negative pressure in the barn. When the fans are switched on, a negative pressure is created in the barn, which draws fresh outside air in.
In the central exhaust system, High Pressure Fans are placed in a roof duct in the ridge of the roof. From there, the fans keep the negative pressure in the central channel stable. Through inlets at the bottom of the channel, the various areas are provided with minimum to maximum ventilation. In this way, these areas are supplied with air independently of each other. Furthermore, an air washer can be connected to the outlet side of the group of High Pressure Fans.
The resistance in the central channel is usually around a ∆Stat of 50 Pa (this value depends on the type of barn). When using these systems, even with speed regulation, a ∆Stat of at least 50 Pa is expected at all times and a High Pressure Fan must meet these requirements.
In regions with strict laws and regulations regarding emissions, it is often mandatory to install air washers. In that case, a High Pressure Fan is also an essential addition to the barn. In our second article in this series, we will further discuss the advantages and disadvantages of using central exhaust systems in pig barns.
Are you wondering whether a High Pressure Fan is the right solution for your application or would you like some additional information about the possibilities? Take a look at our High Pressure Fan page or ask any questions you might have to one of our specialists. They will gladly advise you.
