When it comes to designing a duct system, it is essential to consider the pressure loss that will occur in the system. Pressure loss, also known as friction loss, is the total pressure loss in a duct or joint. In an equal-friction design, all ducts must have the same pressure loss per unit length. Therefore, once the critical path is identified, duct losses can be calculated simply by multiplying the design pressure loss (inches wg per 100 feet) by the total length of the critical path divided by 100 feet.
The following table can be used to estimate friction loss in air ducts. It is important to note that air carried by a duct system imposes static and dynamic pressures (velocity) on the duct structure. This is why it is beneficial to use total pressure for duct calculation and testing instead of using only static pressure. To accurately calculate pressure loss in a duct system, you need to consider several factors. First, you need to identify the critical path in the system.
This is the path that has the highest pressure loss per unit length. Once you have identified this path, you can then calculate the total pressure loss by multiplying the design pressure loss (inches wg per 100 feet) by the total length of the critical path divided by 100 feet. You also need to consider other factors such as air velocity, air density, and duct size when calculating pressure loss in a duct system. Air velocity affects the amount of friction that occurs between the air and the walls of the duct. Air density affects how much air can be moved through a given area.
Finally, duct size affects how much air can be moved through a given area. Once you have calculated the total pressure loss in a duct system, you can then use this information to determine how much energy is required to move air through the system. This information can then be used to determine how efficient your system is and how much energy it will require to operate. Calculating pressure loss in a duct system can be a complex process. However, with careful consideration of all of the factors involved, you can ensure that your system is efficient and cost-effective. By understanding how to calculate pressure loss, you can make sure your duct system is designed correctly and operates efficiently. With this knowledge, you can save money on energy costs and ensure your system runs smoothly.