To accurately determine air http://www.selleckchem.com/products/U0126.html pollutant emission rates from an animal building, continuous measurement of ventilation rate and pollutant concentration are both imperative, because the air pollutant emission rate is the product of ventilation Inhibitors,Modulators,Libraries rate and pollutant concentration. The concentrations of pollutants can usually be analyzed off-site by collecting samples from animal buildings with subsequent laboratory analysis, or determined on-site and real-time by using gas analyzers or sensors. Although pollutant sampling and concentration measurement has a common issue Inhibitors,Modulators,Libraries with quality assurance and quality control [11], ventilation measurement appears to be more technically challenging. As a consequence, ventilation rate measurement typically introduces the greatest uncertainties in air pollution emission rate estimations [12].
The current methods for ventilation rate measurement varied in different studies at different types of animal buildings. There are three continuous Inhibitors,Modulators,Libraries monitoring methods available for the mechanically ventilated animal buildings with large numbers of ventilation fans. They include fan rotation methods, airspeed measurement methods, and fan indication methods [13]. The fan rotational speed method employed the fan rotational speed (FRS) sensor, which is used to monitor the fan blade rotational speed. However, the cost of the FRS sensor and its data acquisition hardware is relatively high and its large scale application is expensive. The fan air speed measurement method utilizes small impeller anemometers for continuously Inhibitors,Modulators,Libraries measuring the air velocity Dacomitinib at a fixed point in the fan outlet.
Nevertheless, the price of the anemometer is even higher. The fan indication method employs sail switches, vibration sensors, contact relays, and other devices to monitor fan on/off status. These devices are relative low priced and suitable for large scale applications. However, the sail switch is susceptible to mechanical failure and sensitive to dust build-up. Vibration sensors make it clear were introduced to fan on/off status monitoring in 2005 [14]. The principles of the vibration sensor measurement were illustrated by Ni et al. [14] and Darr et al. [15].Fan on/off status represents the fan operation and can be used to record the operation time of individual fans. The recorded data are valuable in estimating fan airflow rates to improve pollutant emission rate calculation. Fan on/off data can be converted to airflow rate by using fan performance models and static pressures. The fan performance model describes the mathematical relationship between fan airflow rate and the static pressure that the fan has to overcome. It can be obtained in controlled laboratory conditions and verified on-site using a portable fan testing device or the traverse method.