Tunnel guards

Experimental data on heat transfer from spheres to an air stream are shown in Fig. 5.20. Despite the large number of studies over the years, the amount of reliable data is limited. The data plotted correspond to a turbulence intensity less than 3%, negligible effect of natural convection (i.e., Gr/Re <0.1 see Chapter 10), rear support or freefloating, wind tunnel area blockage less than 10%, and either a guard heater on the support or a correction for conduction down the support. Only recently has the effect of support position and guard heating been appreciated a side support causes about a 10% increase in Nu... 

I hesitated for a moment at the Porta della Carta, so that Bruno went another step and turned to look for me, but then I forced my feet to move again and we entered the tunnel. The same guard shot the same startled look at Bruno, slammed the butt of his pike down on the same flagstone, and asked the same question. 

A form of distance guard whereby access to the area of hazard of the machine is prevented since materials are passed into the machine via a metal enclosure or tunnel. It is commonly used on metal cutting machines and usually incorporates an interlock, so if the tunnel guard is raised the machine stops operating. 

Workpieces should be supported properly. Tunnel/ Shaw guards should be used where appropriate. Noise attenuation should be applied to the machine, for example damping, special quiet saw blades and If necessary fitting In an enclosure. Hearing protection may have to be used. 

Design a plan for guarding pedestrian traffic without a tunnel or crossover. What would your procedure encompass ... 

Experience has shown that the Safety Officer s influence on safety is limited. He cannot, for instance, decide whether steel shutter units should have built-in guard rails, when and where safety nets should be used, or whether rock conditions are sound for work in tunnels. These are decisions taken by other members of the Contractor s staff who are more experienced than the Safety Officer in heavy construction operations. 

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