Balancing of Industrial Ventilation Systems

Crowder, Jerry W.; Loudermilk, Kenneth J.

doi:10.1080/00022470.1982.10465366

Cited by 2 publications

(4 citation statements)

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“…There are three problems with adjusting dampers to achieve a goal value: (1) if the fan airflow is insufficient, the process will fail, forcing the practitioner to adjust the fan output and start over; (2) if the fan airflow is excessive, the fan pressure will be higher than could be achieved using proportional methods; and (3) the branch airflow and static pressures will rise as each subsequent damper is adjusted. The first two problems are sufficient reason to prefer proportional methods for most systems.…”

Section: Adjustment Targets For Each Damper In the Target Methodsmentioning

confidence: 98%

“…This can be done using orifices whose resistances to flow can be predicted or by using estimates of X damper determined experimentally for common damper types, such as the estimates published by Crowder and Loudermilk (2) and Idel'chik. (3) In addition, the Static Pressure Ratio Method (1) uses resistances to predict the ratio of the hood static pressure to the static pressure just upstream of the junction fitting for each branch duct and then bases adjustment of dampers on achieving the predicted ratios.…”

Section: Strategies For Adjusting Dampersmentioning

confidence: 99%

“…The difficulty in each case is in predicting the values of X damper that are required to achieve the desired distribution of airflows. The computations require a sophisticated pressure model of the installed system, (2) making such predictions difficult without specifically written software.…”

Section: Strategies For Adjusting Dampersmentioning

confidence: 99%

“…The effect on the fan airflow of increased system resistance as dampers were adjusted was simulated by modeling the relationship between the resistance of the system (X system ) and the airflow level produced by the fan (Q fan ) at a fixed rotation rate. The resistance of an entire system can be approximated by: (1,2) X system = TP fan VP fan inlet (24)…”

Section: Example System and Computationmentioning

confidence: 99%

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A Goal Method and a Target Method for Balancing Exhaust Ventilation Duct Systems with Dampers

Guffey

2007

Journal of Occupational and Environmental Hygiene

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This work presents and discusses two approaches to adjusting dampers, here called the Goal and Target Methods. A form of the Goal Method is commonly employed but has not been clearly described or discussed elsewhere. The Target Method is a novel variation of so-called "proportional" methods. Detailed step-by-step procedures for each are presented. It is likely that the most common method of balancing the airflows in ventilation systems is simply to adjust the damper in each branch in turn until the observed airflow for each branch duct (Qbr) equals the goal airflow (Qbr-goal). This is a simple Goal Method. It is difficult and time-consuming due to interactions among branches and with the fan. As one adjusts a damper to reduce airflow in that duct, all other airflows increase. As each damper is inserted, the overall resistance of the system increases, reducing fan output. The Target Method uses target values of centerline velocity pressure (VPcl) or hood static pressure (SPh) computed from the measured values of VPcl and SPh multiplied by factors intended to account for (a) initial Qbrand Qbr-goal, (b) the interactive effects of dampers on branch airflows, and (c) a model that predicts the reduction in fan airflow due to the dampers. Simulations on a computer spreadsheet predict that the Target Method will produce better accuracy for fewer adjustments than the goal method, but it is more computationally difficult.

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Section: Adjustment Targets For Each Damper In the Target Methodsmentioning

confidence: 98%

Section: Strategies For Adjusting Dampersmentioning

confidence: 99%

Section: Strategies For Adjusting Dampersmentioning

confidence: 99%

Section: Example System and Computationmentioning

confidence: 99%

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A Goal Method and a Target Method for Balancing Exhaust Ventilation Duct Systems with Dampers

Guffey

2007

Journal of Occupational and Environmental Hygiene

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Experimental validation of the "target hood static pressure" balancing method for exhaust ventilation systems

Dodrill¹

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An experimental trial of a new method to balance industrial exhaust ventilation systems was performed. Although balance by design is considered preferable, many ventilation systems incorporate dampers to balance the system to a different airflow distribution after installation. The "target hood static pressure" method aims to minimize the time, effort, frustration and confusion invested in the balancing effort. It requires only one and one-half adjustment rounds, can be prepared as a computerized spreadsheet, and substitutes hood static pressure readings for airflow traverse readings. The method also minimizes the system static pressure to the least possible, thereby keeping friction losses at a minimum. Since the resulting distribution errors range less than the measurement error of pitot tube measurements, no method can be demonstrated as being better.

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Balancing of Industrial Ventilation Systems

Cited by 2 publications

References 0 publications

A Goal Method and a Target Method for Balancing Exhaust Ventilation Duct Systems with Dampers

A Goal Method and a Target Method for Balancing Exhaust Ventilation Duct Systems with Dampers

Experimental validation of the "target hood static pressure" balancing method for exhaust ventilation systems

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