For both mechanical contractors and HVAC engineers, the turning vane is one major source of contention. This has been so because of several contractors believe that the turning vanes are capable of causing ductwork hence becoming less efficient by increasing pressure drop in the system. In addition, it adds time and expenses to overall installation. The logic behind this believe is that whenever there is more surface area exposed to airflow, there increase in friction. The fan also works harder in this case so as to achieve required air-flows.
In cases when the HVAC system has particular difficulties in supplying the ideal amount of airflow to concerned zones, it is recommended by many mechanical contractors to remove each and every vane at every fitting in the system. This helps to reduce the amount of friction in a duct. This practice is however not recommended by the SMACNA as it tampers with the turning vane spacing which is required. It also decreases uniformity of airflow as well as increasing the pressure drop in this system.
One should however be conscious of some vital facts with regards to the individual vane. A change in airflow course within the duct devoid of vane, the flanking walls of these duct must soak up the sudden impact thus leading to change of the airflow in principle route. The most important function of these vanes is to assist in airflow.
Turning of a vane can lead to an 800 percent increase in efficiency in an elbow. However in the case of a cheaper installation, one may establish that installation of a radius elbow that lack any vane will be a better option. This technique is considerably more efficient as it is cheap and easy to install as well as fabricate.
In other cases, a vane may be what leads to a prominent pressure drop. A sample scenario is when the a vane is put up at the opening of ducts. Huge losses of pressure are caused by such configurations due to specific vane unsettling the regularity of the flow of air within the central duct. Although the costly during fabrication, radius fitting is the most efficient compared to entry fitting as the setting up cost is equal for both forms of fitting.
Unseemly vane alignment in the ducts also acts as another aspect that leads to a drop in pressure owing to an increase in air turmoil. The turmoil is caused by the vanes not been aligned analogously. The airflow comes into impact with the ducts thus leading to turmoil.
The result of misalignment differs with regard to how far flung these vanes are aligned. Hurried and shoddy installation are the main causes of improper alignment and can be evaded by carrying out checks and balances throughout the installation. This is more often than not the contractors duty.
Consequently it is apparent that vanes support the drop in pressure loss as well as ensure that there is an increase in efficiency. An engineer should therefore ensure that several factors are considered during the design such as, the best fittings are considered depending on the owners cost budget. The contractor is also expected not to make any changes to the designs.
In cases when the HVAC system has particular difficulties in supplying the ideal amount of airflow to concerned zones, it is recommended by many mechanical contractors to remove each and every vane at every fitting in the system. This helps to reduce the amount of friction in a duct. This practice is however not recommended by the SMACNA as it tampers with the turning vane spacing which is required. It also decreases uniformity of airflow as well as increasing the pressure drop in this system.
One should however be conscious of some vital facts with regards to the individual vane. A change in airflow course within the duct devoid of vane, the flanking walls of these duct must soak up the sudden impact thus leading to change of the airflow in principle route. The most important function of these vanes is to assist in airflow.
Turning of a vane can lead to an 800 percent increase in efficiency in an elbow. However in the case of a cheaper installation, one may establish that installation of a radius elbow that lack any vane will be a better option. This technique is considerably more efficient as it is cheap and easy to install as well as fabricate.
In other cases, a vane may be what leads to a prominent pressure drop. A sample scenario is when the a vane is put up at the opening of ducts. Huge losses of pressure are caused by such configurations due to specific vane unsettling the regularity of the flow of air within the central duct. Although the costly during fabrication, radius fitting is the most efficient compared to entry fitting as the setting up cost is equal for both forms of fitting.
Unseemly vane alignment in the ducts also acts as another aspect that leads to a drop in pressure owing to an increase in air turmoil. The turmoil is caused by the vanes not been aligned analogously. The airflow comes into impact with the ducts thus leading to turmoil.
The result of misalignment differs with regard to how far flung these vanes are aligned. Hurried and shoddy installation are the main causes of improper alignment and can be evaded by carrying out checks and balances throughout the installation. This is more often than not the contractors duty.
Consequently it is apparent that vanes support the drop in pressure loss as well as ensure that there is an increase in efficiency. An engineer should therefore ensure that several factors are considered during the design such as, the best fittings are considered depending on the owners cost budget. The contractor is also expected not to make any changes to the designs.
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