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...

Introductory Air balancing, trouble-shooting, and system evaluation in dust collection and industrial ventilation systems all require accurate measurements of air flowrates. Normally, the Pitot tube and magnehelic gauge (or manometer) are used to measure the velocity pressure and static pressure inside of a duct (round or rectangular), and then the air flowrates are calculated based on the measured values. This article talks about 5 kinds of uncertainties that always happen in field measurements using Pitot tube, the estimated maximum errors with some of them, and how to avoid some uncertainties with recommendations from manuals and standards ( ISO 3966 and NF X 10-113).   Uncertainties, maximum errors, and how to avoid some of them In addition to the inherent errors from Pitot tube and gauges themselves (calibration, resolution, drift, etc., sometimes with the correction factor of Pitot tube involved), there are other errors we have to...

  In a dust collecting system, the duct, fan, and dust collector are all susceptible to abrasion from dust particles, high-velocity gas flow, and chemical corrosion. The elbows are most vulnerable to abrasions. Air leakage around an access-door or hopper and loose flange isn’t uncommon either. Many times, these holes on ductwork, fans, and dust collectors are not repaired and left alone, so they grow bigger and bigger and air leakage becomes an even worse problem. Airvate did some calculations to estimate sucked-in air volume through a hole based on available data regarding the hole’s area and gauge pressure inside of a duct or dust collector. The calculations are listed in the table below. Along with the sucked-in air volume, moisture volume is also listed in the last column for an 8-hour shift assuming that the sucked-in air is saturated with water vapor, like what would happen on a rainy day. 4 hole-sizes are selected: 3 round holes of sizes 7/16”, ½”, and 1” in diamet...