Roofing

Following the fire in 1953 at General Motors transmission plant (Livonia, MI, USA), it was realised that there was a need for test methods for roofing systems and the 

Eor proper risk assessment of the fire performance of metal roof constructions, model fire test studies were done [15]. The trials carried out by TNO indicated that the fire performance classification of the insulation was the main factor influencing fire spread along the upper roof system to adjacent sections. 

Sommer [16] has discussed the suitability of halogen-free fire retardant systems from meeting the specifications of fire regulations in the building, rolling stock and electrical industries. 

Representatives of various industries [17] have examined some smoke depressants and flame retardant resins introduced by various US Companies in relation to US legislation. These include smoke suppressed polyvinylchloride (PVC) (BE Goodrich) and polyurethane (PU) foams (Mobay Chemical), and smoke suppressant additives from Climax Molybdenum, and Sherwin-Williams (molybdenum compounds), Solem Industries, and Alcoa Chemicals (aluminium trihydrates, for polypropylene (PP) and PVC), Dover Chemical Corp., (aromatic bromine compound for PP), and US Borax (zinc borate). 

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Floating Roof. Floating roofs can be used as shown in Fig. 9.2a. 

Figure 9.2 Floating roofs and flexible membranes can be used to prevent the release of material. (From Smith and Petela, The Chemical Engineer, no. 517, 9 April, 1992 reproduced by permission of the Institution of Chemical Engineers.)...

This eliminates the vapor space but sealing the edge can be a problem. Double seals can help and sometimes a fixed roof is also added above the floating roof to help capture any leaks from the seal. However in this case, the space between the fixed and floating roof now breathes and an inert gas purge of this space would typically be used. The inert gas would be vented to atmosphere after treatment. 

Flexible membrane. Another method to stop the vapor space breathing to atmosphere is to use a tank with a flexible membrane in the roof, Fig. 9.26. 

Waterproofing, whether it has to do with protecting civil engineering structures or roofs or terraces. Poured asphalt, often placed in layers with kraft paper, oxidized bitumen or modified bitumen can be used, generally with copolymer. The modified bitumen are used for the making prefabricated multi-layer waterproofing composites. 

To reduce these losses, the crude oils are stored in floating roof tanks. 

Figure 10.29 Fixed roof and floating roof storage tanks...

Sheets of galvanised iron are used for roofing, guttering and the like. Alloys of zinc, notably brass, are used extensively. The metal is used m wet and dry Leclanche batteries. 

In professional laboratories fume hoods are big metal boxes resting on counter tops and are connected by ducts to blower motors on the roof of the facility. The blower motor is constantly sucking the air from the hoods to the outside so that chemists will not be exposed to the vapors of chemicals they are working with inside the hood. The same precautions are taken by non-dead underground chemists. 

Membrane filtration Membrane module Membrane permeability Membrane process Membrane processes Membrane reactor Membrane roofing Membranes... 

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