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System Selection and Optimization
Published in Samuel C. Sugarman, HVAC Fundamentals, 2020
When properly controlled the outside ventilation air can aid the heating, cooling and humidifying of the building spaces. It can also provide a positive static pressure in the conditioned spaces. This positive pressure reduces the amount of air infiltration. Commercial buildings will generally be pressurized at about 0.03 to 0.05 inches of water column static pressure.
Vadose Zone Monitoring
Published in Daniel B. Stephens, Andrea J. Kron, Andrea Kron, Vadose Zone Hydrology, 2018
Daniel B. Stephens, Andrea J. Kron, Andrea Kron
In some portions of the vadose zone, it is possible that saturated zones occur where fluid pressure is greater than atmospheric. These parts of the vadose zone could include inverted water tables beneath losing streams or perched aquifers, for instance. The simplest method to measure in situ positive pressure is with piezometers, although mercury manometer and transducer-type tensiometers can also function under limited positive pressures. The soil mechanics literature describes the many different types of pore pressure piezometers that are commonly in use (e.g., Russell, 1981), and some piezometers with porous stone tips are capable of measuring negative as well as positive fluid pressure. Groundwater hydrologists conventionally construct cased monitor wells to measure water levels as indicators of fluid pressure, so we do not elaborate further on their design. However, we must point out that the monitor wells will not record negative fluid pressure. Consequently, care must be exercised first in placing monitor wells in zones likely to be saturated and second in interpreting time-series data where both positive and negative pressure occur in the soil.
Fermentors and Operation of Fermentation Equipment
Published in Nduka Okafor, Benedict C. Okeke, Modern Industrial Microbiology and Biotechnology, 2017
Nduka Okafor, Benedict C. Okeke
It is important to know the pressure of gases in order to ensure that a positive pressure is maintained. A positive pressure helps eliminate contamination and contributes to the maintenance of proper aeration. Pressure may be determined with aid of a manometer
Experimental study on dust removal optimization of shearer external spray in air velocity
Published in Journal of Environmental Science and Health, Part A, 2020
Jiangshi Zhang, Tianliang Sun, Xuesong Yang, Jianhua Liu
The principle of the emulation spray experiment system is shown in Figure 1. A custom water spray test system produced by Jinan deco pump industry Co was used in this experiment. The system has an input voltage of 220 V and a storage capacity of 5 L. The pressure range of the system cylinder is 0–40 MPa, that is, the storage pressure of the system, and the output pressure system is 0-25 MPa so that any pressure adjustment between 0-25 MPa can be realized. Meanwhile, the air compressor is used to pressurized the water spray system. The spray pipe was composed of a metal pipe and the plastic pipe. A solid conical nozzle is used in the experiment, whose material is stainless steel. The particle size analyzer’s transmitting terminal and receiving terminal was 2 meters apart from the axis of atomizing field, and the laser was perpendicular to the axis. The positive pressure ventilation was used, and the air pressure was provided by a blower. Moreover, the direction of airflow was perpendicular to the laser and the axis on different planes.
Advances in dewatering and drying in mineral processing
Published in Drying Technology, 2021
Benitta A. Chaedir, Jundika C. Kurnia, Agus P. Sasmito, Arun S. Mujumdar
For fine concentrates (<30 µm), pressure filtration has certain advantages over vacuum filtration. In pressure filters, positive pressure is implemented since the higher pressures was found to increase flow rates and improve washing and drying result. The typical pressure filters adopted in mineral dewatering can be categorized into two types based on the direction of the applied pressure and the orientation of the filter plates; i.e., horizontal and vertical.[3] In the horizontal filter arrangement, filter plates are vertically suspended from a steel scaffolding (from which the name “vertical plate pressure filter” is given), and filter cloth is hung between the plates. The plates are bound together by a hydraulic piston which also opens and closes the press. The feeding cycle starts with the slurry being fed into the chamber inside press. Once it is full, the membranes on one side of the chamber are pressurized to maintain the cake steadily and force the water to come out of it. The main dewatering process is then commenced by supplying pressurized air of up to 8 bars through the cake. At the end of the process, the cake is extracted by opening the press and separating the plates. While the operation of this filter is batch, operation appears continuous with cycle times of around 10 min.[3] The filtration process with vertical pressure filters is similar to that of the horizontal counterpart. The only difference is in the stacking arrangement; the chambers are stacked on top of each other, and in the filter cloth configuration; one continuous instead of individual filter cloths.