Influence of a local ventilation system on patient and personnel protection in operating rooms.

Temperate buildings are comfortable, safer and more productive places to work. Ensuring that extremes of cold and heat, and airborne diseases are mitigated is through effective design, function and management of ventilation systems. This book addresses the basics of ventilation systems and their use in building-based workplaces and how to ensure they are managed successfully. This book provides comprehensive technical information regarding the design and implementation of dilution and local exhaust ventilation systems to ensure safe and productive workplaces. It presents a simple and readable summary of how to design, install, and operate industrial ventilation systems, all highlighted through illustrations and tables. This title is written to international standards on the design of dilution and local exhaust ventilation systems, including ASHRAE and ACGIH standards. Design of Workplace Dilution and Local Ventilation Systems is an ideal reference for safety engineers, designers, specialists, engineers, architects, and contractors tasked with ventilation systems. It is also a useful reference for undergraduate and graduate students to master the complex fundamentals of designing dilution and local exhaust ventilation systems.

Local exhaust ventilation systems for the gross anatomy laboratory

Biological particles in the operating room (OR) air environment can cause surgical site infections (SSIs). Various ventilation systems have been employed in ORs to ensure an ultraclean environment. However, the effect ofdifferent ventilation systems on the control ofbacteria-carrying particles (BCPs) released from the surgical staff during surgery is unclear. In this study, the performance of four different ventilation systems (vertical laminar airflow ventilation (VLAF), horizontal laminar airflow ventilation (HLAF), differential vertical airflow ventilation (DVAF), and temperature-controlled airflow ventilation (TAF)) used in an OR was evaluated and compared based on the spatial BCP concentration. The airflow field in the OR was solved by the Renormalization Group (RNG) k-ε turbulence model, and the BCP phase was calculated by Lagrangian particle tracking (LPT) and the discrete random walk (DRW) model. It was found that the TAF system was the most effective ventilation system among the four ventilation systems for ensuring air cleanliness in the operating area. This study also indicated that air cleanliness in the operating area depended not only on the airflow rate of the ventilation system but also on the airflow distribution, which was greatly affected by obstacles such as surgical lamps and surgical staff.

Chapter 6 - Commissioning, control, and maintenance of ventilation systems

97/03169 The demise of the primary-secondary pumping paradigm for chilled water plant design

The aim of this study is to determine how the air flow from a unidirectional air flow (UAF) system and a local ventilation system will interact with each other. The study analyzes the air circulation near the operating table at different air flow velocities from both systems. The air flow velocities correspond to the usual range of velocities recommended by norms and guidelines. The research was approached by numerical and experimental studies. The thermal plume of the occupants (patient and surgeon) were measured by Particle Image Velocimetry (PIV) and thermography (IR). The results of the measurements were compared with the results from the numerical case. A mesh independence study was carried out for the numerical case. The study showed that velocities ≥0.2 m/s from the UAF, depending on the height of the room, can overcome the thermal plume generated by a human subject with a moderate activity (100÷120W). The velocities from the local ventilation system need to be higher with at least one step, in accordance with the distance from the ventilation system to the operating wound, in order to avoid disturbances generated from the UAF system.

Although the incidence of pneumoconiosis has been decreasing in Japan, welders’ health hazards due to welding fume inhalation are still serious, because effective engineering methods for controlling fumes are technically difficult to implement in many welding shops. In the 6th notification of general prevention of dust hazards issued by the Japanese Ministry of Health, Labor and Welfare (2003–2007), a fume-exhaust gun system was recommended as an effective ventilation device for welding fume control. An ordinary fume-exhaust gun system consists of a welding torch with a suction hood which exhausts the air around the welding arc, a fume collector, and a flexible duct which connects the hood to the collector (Fig. 1). The ventilation is supposed to be performed effectively by means of the suction hood distributed around the periphery of the torch. The air contaminated with welding fumes is carried from the hood through the flexible duct to the fume collector where it is cleaned and then recirculated to the welding shop. Since a fume-exhaust gun requires much lower air removal than other local ventilation systems or a general ventilation system, it should be beneficial to the running cost of the ventilation. In addition, a fume-exhaust gun is superior to the other local ventilation systems in applicability. Unlike the fixed hood of a usual local exhaust ventilation system, a fumeexhaust gun has a hood which does not limit the size of the work piece and welder’s mobility because its hood is always close to the arc point and does not require laborious repositioning or adjustment. However, the gun performance will be affected by the geometry of the weld joint and the shielding gas flow rate. When the hood suction is distorted due to some welding position or excess in shielding gas, the fume plume may tend to rise away from the hood of the gun. In this study the author investigated the effects of welding position, elevation angle of weld line and flow rate of shielding gas on fume-exhaust gun performance.

To control chemical hazard, engineering control is one of the Hierarchy of Controls that protects workers from chemical hazard. Engineering control is accomplished by removing hazardous conditions by placing a barrier between the worker and the hazard. Local ventilation system is widely used in laboratories to remove any chemical agents that are released from any chemical reactions. The importance of these ventilation systems is to prevent any health complications to persons in the laboratory due to chemical exposure. İn this paper, the effects and effectiveness of sash height to vapor source position to effectiveness of local exhaust ventilation (LEV) system were studied and identified using vapor flow from the stimulated carbon dioxide (CO2) and water vapor. Eight LEVs were inspected. The stimulated vapor as a tracer was produced by mixing dry ice into hot-boiled water (100oC). The dispersion stimulated CO2 and water vapor inside and outside the LEV system, and this can predict the efficiency of LEV systems based on visual inspection. The results revealed that each LEV showed a different time taken to draw out the vapor from the inside of the fume hood.

An improved experimental method for local clothing ventilation measurement

A study was made to document and evaluate effective techniques for the control of potential health hazards at Kwick Kleen Industrial Solvents, Inc., Vincennes, Indiana. This particular study was born out of a growing concern of the hazards of methylene-chloride and the need for technical advice to furniture strippers. This particular company produced, sold, and distributed furniture stripping solutions to over 2,000 furniture stripping shops. The study evaluated the local ventilation systems designed by the company for their ability to minimize the amount of methylene chloride to which workers were exposed. Three local ventilation systems were used in conjunction with a flow over furniture stripping tank: a hood ventilation system, a PVC pipe ventilation system, and a floor ventilation system. Five different sampling setups or configurations were evaluated. Personal exposures to methylene-chloride while using local ventilation systems were about 200 parts per million (ppm) while stripping which was lower than the control system which used no local ventilation and had an average exposure of 600ppm. Local ventilation systems should be improved to lower the personal exposure levels. No control system was demonstrably better than any of the others. According to the authors, increasing the amount of air exhausted locally frommore » the stripping area might significantly reduce exposures to methylene-chloride. Other suggestions included enclosure of the tank, as well as other tank and ventilation system designs.« less

In response to a request from the President of Simmons Industries, Inc. (SIC-2015), Siloam Springs, Arkansas, the ability of the local exhaust ventilation system in the hanging room of the poultry processing facility to protect chicken hangers from exposures to airborne organic dust was evaluated. Air quality analyses were conducted both at the Siloam Springs facility and at the similar facility of the same company located in Jay, Oklahoma. One of three 8 hour time weighted average (TWA) inhalable dust concentrations from the Siloam Springs facility exceeded the Threshold Limit Value of 10mg/cu m for particulates not otherwise classified. Three similar samples taken at the Jay facility exceeded the limit. The Jay facility did not have a local ventilation system in operation. Endotoxin concentrations in all six of the TWA inhalable samples exceeded the recommended limit of 10 nonagrams/cubic meter (ng/cu m) at both facilities. Of the six samples, five exceeded 100ng/cu m, a level associated with spirometric evidence of acute airways obstruction. The authors conclude that exposures in the hanging rooms of both poultry processing facilities represented a potential health risk. The authors recommend that the exhaust ventilation system and work practices be changed to reduce exposures. A respiratorymore » protection program should be implemented until dust exposures are controlled.« less

Alternative ventilation system for operating theaters: Parameter study and full-scale assessment of the performance of a local ventilation system

Semiclosed tunnels are very common in engineering construction. They are not connected, so they easily accumulate heat. Once a fire breaks out in a semiclosed tunnel, the route for rescue workers to enter is limited, so it is tough to get close to the fire source. In this paper, taking a mine excavation roadway with local pressure ventilation as an example, the temperature field distribution and water spray fire prevention characteristics of the excavation roadway face were studied using numerical simulation and theoretical analysis. This paper provides an explanation of a dynamics-based smoke management method for water spraying in a semiclosed tunnel as well as the equilibrium relationship between droplet drag force and smoke buoyancy. A method was first developed to calculate the quantity of smoke blockage based on the thickness of the smoke congestion. The local ventilation and smoke movement created a circulating flow in the excavation face, which was discovered by investigating the velocity and temperature fields of the excavation face. The size of the high-temperature area and the pattern of temperature stratification varied due to this circulating flow. When local ventilation and sprinkler systems were operating simultaneously, when the volume of smoke was small, the smoke avoided the majority of the water spray effect with the circulation flow; however, when the volume of smoke was large, the effect of the circulation flow decreased and the smoke gathered close to the sprinkler head. At this time, the blocking effect of the water spray was significant. The mean square error analysis revealed that activating the sprinkler had the most significant cooling impact on the wall on one side of the air duct.

Study of the destruction of ventilation systems in coal mines due to gas explosions

An experimental study of annular jets with central aspiration is presented. Two flow regimes were studied for creating either local air conditioning or local ventilation systems. The local air-conditioning system was developed by maintaining the same flow rates of the non-swirling annular jet and central aspiration. A new concept of a ‘local ventilation system’ was created by combining the swirling annular air jet impinging on the plate and central aspiration. Due to the rather small consumption of energy, the tested air-conditioning and ventilation systems are very functional and capable of maintaining local and confined micro-climate or ventilated zones in large volumes.In order to study dynamic and thermal conditions in the air conditioning system an experimental rig was built and tested. The results of the experimental research, using visualization and thermocouple measurements as well as 2D velocity fields obtained by a LDV system are presented and discussed. The visualizations show the existence of a stable calm low velocity zone in the core of the annular air jet. The thermocouple measurements, as well as LDV measurements, prove the dynamic and thermal stability of the region. A dynamically and thermally defined stable local zone is a protected volume where comfort conditions can be maintained. Velocity measurements also show the size of the vortex located between the annular jet exhaust and the central air return.Another experimental rig was built in order to study the conditions created by the proposed ventilation system. The presence of an aspirating ascending jet in the form of swirling flow – tornado, was registered between the proposed device and the impingement plate. This flow regime is very efficient in ventilating the local zone.