China 
Africa 
Explore chapters and articles related to this topic
Flow of Solid-Gas Mixture in Pipe (Pneumotransport)
Published in Henry Liu, Pipeline Engineering, 2017
The prime mover (air pump) of any pneumatic conveying system may be a fan (for low pressure systems of less than about 0.3 bar), a blower (for medium pressure in the range 0.3 bar to 3 bar, approximate), or a compressor (for pressure above 3 bar). For negative pressure systems that must develop a high vacuum (up to about 0.8 bar), a vacuum pump is used, which is usually a piston pump. Chapter 9 contains a detailed discussion of pumps (including air pumps), and their selection, operation, and maintenance.
Work Practices for Removal Projects
Published in Kenneth F. Cherry, Asbestos, 2020
This section provides guidelines, including recommended specifications and operating procedures, for use of negative-pressure systems in removing asbestos-containing materials (ACM) from buildings. A negative-pressure system is one in which static pressure in an enclosed work area is lower than that of the environment outside the containment barriers.
Analysis of parametric optimization on the design of negative pressure room
Published in Advances in Building Energy Research, 2023
Ghaim Man Oo, Komsilp Kotmool, Mongkol Mongkolwongrojn
The advantage of a negative pressure room is that it prevents the contaminant airflow from being exhaled from patients to the outside of the room because the air pressure in the room is lower than the outside pressure room, which means that the airflow moves only from the outside to the inside direction. Consequently, maintaining specified stable negative pressure in the isolation room is an important point in the airborne infectious isolation room (AIIR) design process. The required minimum pressure difference and ACHs are 2.5 and 6 Pa respectively, according to ASHRAE/ASHE Standard 170–2017 in Ventilation of Health Care Facilities. Furthermore, the design standards of negative pressure rooms or AIIR vary based on the different countries (Refrigerating, 2013). Negative pressure rooms are considered together with buffer rooms and the main isolation room with desired pressure. The buffer room is located between the corridor and the main negative pressure room to prevent particles and pollutants from penetrating the main room and this room area is approximately 6.97 m2 (Arpino et al., 2020). The outside air passes through this buffer room and flows into the negative pressure room and then escapes through the air filtration system.
Study of the Explosion Suppression Mechanism of Different Separate and Explosion-Proof Materials
Published in Combustion Science and Technology, 2022
Jiancun Gao, Xigang Yang, Shoutao Hu, Le Wang, Zijin Hong, Ruxia Li, Xu Sun
These materials were processed into a uniform cylindrical and dense filling based on the shape of the pipe. Additionally, 5% crevice rate (the ratio of space to container volume of unfilled separate and explosion-proof materials) was left at the ignition head end of the pipeline for effective ignition. The device was made airtight, followed by replacing the air in the pipe with synthetic air (79% N2, 21% O2). A vacuum pump was then used to achieve negative pressure. This was followed by filling with 57 mL C3H8 (5% volume fraction), and the synthetic air was replenished with the pipe to atmospheric pressure. The gas in the pipe was homogenized evenly. An ignition system was used to detonate the gas. The experiments were carried out in accordance with industry standards and replicated to ensure repeatability. Pressure data were measured with a pressure data collector. After the gas explosion, the sampling system was used to collect the gas explosion products. Explosion product collection device is shown in Figure 2.
VOCs concentrations and emission rates in hospital environment and the impact of sampling locations
Published in Science and Technology for the Built Environment, 2021
Marko Hyttinen, Paavo Rautiainen, Joonas Ruokolainen, Jouni Sorvari, Pertti Pasanen
A hospital environment can in many cases be exceptional; for example, depending on the use of the room, it can deliberately have either negative or positive pressure compared to surrounding areas (Hyttinen et al. 2011). For example, airborne infection isolation rooms (AIIRs) need to have negative pressure versus surrounding areas. Although some harmonization of the ventilation requirements for hospitals worldwide has been carried out, a consensus has not yet been reached for ventilation guidelines for the specific rooms (e.g., isolation rooms) in the hospitals. Furthermore, besides the different guidelines, field studies have revealed that there are deficiencies in the performance of these rooms when comparing them to the ventilation reference values given in the national guidelines (Pavelchak et al. 2000; Saravia et al. 2007; Sutton et al. 1998).