Airvate Blog

  Three sections in this blog post: The value of obtaining ventilation test data,  Baseline Test,  Periodic Tests.  Periodic Test on an Industrial Ventilation System When Airvate did air balancing, trouble-shooting, field survey, and whole system evaluation of an industrial ventilation and dust collection system, we always recommended customers to obtain baseline test results after any new system is installed and to do periodic system tests to any existing system. The designer, installer, or their subcontractor should conduct the first, baseline, system test right after a system is installed. The system provider should provide evidence that the system is operating according to its design specifications. Periodic tests should also be made throughout the life of the system to ensure continuing performance, detect problems in the system, and monitor the effects of any changes in ventilation or in production practices. The value of obtaining ventilation test data is...

Three sections in this blog post: There are reasons for "lack of maintenance" Ventilation systems need to be designed to include access for cleaning and preventive maintenance One example of the benefits of easy access for maintenance Airvate engineers have worked with customers for many years and talked with plant management and maintenance guys a lot. We understand their feelings of embarrassment which are hard to mention. There are reasons for "lack of maintenance" Ventilation systems often are installed and then ignored until complaints or obvious problems force attention. This neglect may be due to insufficient knowledge and motivation.  Final users normally don't employ any professional engineer to operate and maintain these dust collection and ventilation systems, especially for small and medium-sized ones as they are "secondary". We hear many times that inadequate or no maintenance caused problems in the systems. I personally believe it is unfa...

  Introduction A damper is a device that adjusts the volume of airflow passing through the outlet, inlet or duct. By proper adjustment of all dampers in a system, a desired distribution of airflows in all the branches can be obtained, while minimizing the total airflow of the system to save energy— this is also termed air balancing. The most common dampers used in industrial ventilation and dust collection systems to balance airflows are slide gate dampers (The slide gate, also called “blast gate or cut-off” damper). In a slide gate damper (see Figure 1 of a straight flat slide gate damper), the slide is inserted perpendicular to the flow. Figure 1 A sample of straight flat slide gate damper As the gate is sliding into the duct, it will add resistance to the airflow and consequently reduce the volume of airflow, while increasing airflows in all other branches. Withdrawing the gate has the reverse effect on that branch and all the others in a system. Interaction between a fan ...

  Introduction The performances of all the hoods in the whole system normally decide the success of industrial ventilation and dust collection systems from the point of a system owner’s view. The appropriate hood design and its needed airflow rate require the application of good ventilation practice, mastery of the technical knowledge and the ability and patience to do the mathematical calculations. When more than one hood is connected to one ventilation system, the design engineer has to assure that each hood can and will receive the volume of airflow equal or above its designed value and the whole system operates with the minimum possible airflow rate to save energy. This task is termed air balancing of the system or duct balancing. Unbalanced systems cause problems On the contrary, examine the case where one or more hoods are unable to receive desired volume of airflow from an unbalanced ventilation system. It is not uncommon that many hoods are receiving airflow volumes...

  Introduction Most baghouse users are confused why their baghouses suffer moisture condensation problems in winter. This blog post tabulates the dew-point temperatures of the airflows with different Relative Humidity (RH) at three different airflow temperatures of 68 o F, 120 o F and 250 o F to show why moisture problems in baghouses or cartridge collectors occur   in winter. Definitions of dew-point and Relative Humidity Dew-poin t is defined as the temperature at which condensation begins when the air is cooled at constant pressure. Relative Humidity (RH) expresses the moisture content of air as a percent of what it can hold when the air is saturated. The temperature of the airflow from a process will likely remain fairly constant and warm year round. However, a temperature differential (approximately 15 o F or more) between the dust collection point and the dust collector may indicate a potential condensation risk. Condensation in a baghouse causes problems When wate...

The pressure loss of a cyclone separator is divided into three main contributions from: the cyclone inlet, cyclone body, and vortex finder (gas outlet). The gas swirl inside the cyclone body is very useful for particle separation, but as this swirl exits the cyclone through the gas outlet, the rotational energy which is stored within is actually lost. This is the main source of the pressure loss of a cyclone separator. A lot of studies have been conducted trying to reduce the pressure loss caused by this rotational energy in the exiting gas flow through modifications on the gas outlet: Modify the length and diameter, Change its shape from cylinder-shape to cone-shape. These modifications can indeed reduce the pressure loss, but cannot be done to existing cyclones inexpensively. Some studies looked outside of a cyclone separator. Here are two examples. In one study, in order to minimize the cyclone’s pressure loss, a pressure recovery type diffuser known as a radial diffuse...

  Outline of this blog post Introduction   Comparison of Standard and Oversized cyclone performances (calculations by Airvate) Recommended applications of oversized cyclone Summary and conclusions Introduction Cyclone separators are widely used in many industrial applications where it is necessary to remove the dust or particles from gasses. These devices are simple with no moving parts and are easy to maintain. Although the construction of these devices is simple, the physics governing the flow process in them is complex. Normally cyclone designers follow two procedures to size a cyclone. Classical Cyclone Design process, and Texas A&M Cyclone Design method The results from these procedures are usually called standard cyclones, while an oversized cyclone is the one from the same family but with a bigger body diameter and, consequently, with a lower inlet velocity at the same air flowrate. Normally, an oversized cyclone can have a lower pressure loss at t...