Temporary water supplies

Temporary water supply connections may be made to bridge impaired components. 

In modem sprinkler systems (shown diagrammatically in Figure 4.2.10) water is supplied at pressure from tire town mains which charges a pressure tank. When a sprinkler head mptures, the loss of water pressure in the supply pipe triggers the alarm valve. The alarm is actuated by the alarm valve either by diverting part of tire water flow to a hydraulic gong or by actuating an electrical alarm. The pressure tank acts as a buffer to absorb any water hammer effects and to provide a temporary water supply if the mains flow is intermpted. 

Lime is the largest toimage chemical used in the treatment of potable and industrial water supplies. In conjunction with alum or iron salts it is used to congulate suspended solids and remove turbidity. It is also used in water softening to remove temporary (bicarbonate) hardness. Typical reactions are ... 

If there is just one point outside the action limits, there should be an immediate evaluation. If there are two points or more in a brief period of time, the system should be shut down and analyzed for the cause. An example is Figure 5.13. As stated there, one possibility is a temporary contamination in the distilled water supply, which is certainly a concern even for a short period of time. A system out of statistical control, even for a short period of time, diminishes the reliability of any results. 

Each of the dissolved minerals in any given source of makeup water has a potential for causing difficulties to a greater or lesser extent. For most water supplies, the commonest and highest levels of dissolved solids are the temporary hardness salts, calcium and magnesium bicarbonates. These are also the dissolved solids that most readily produce crystalline scales and thus contribute to cooling system deposits. Bicarbonates and carbonates provide the total alkalinity (M alkalinity) in most cooling waters, and normally there is no free hydroxide alkalinity. 

Chlorine addition may be a prerequisite to sanitize the RO feed-water supply line and oxidize any organics (followed by dechlorination using sodium bisulfite, after the MM filtration stage). Where chlorine is required, it is usual to provide a 20- to 25-minute contact period by means of a temporary storage tank. This is then followed by a repressurization pump system. 

The mechanical contractor is usually also responsible for providing adequate pressurized water supply, drainage (with special provisions for low-level areas of the closed-loop water system), bypasses, an electrical supply (typically 110 V, 1 phase, but also 3 phase where temporary pumps are required), HVAC system air purge vents, as well as other facilities, such as site access, toilets, security, and equipment handling systems. 

They also deposit insoluble calcium or magnesium carbonate onto heated surfaces to cause scale buildup, so that heating for removal is not of practical use. Interestingly, addition of calcium in the form of slaked lime (Ca(OH)2) can efficiently remove much of the temporary hardness of natural water supplies (Eqs. 5.12-5.14). 

Deep underground storage is planned not only for future high level wastes, but also for the materials now in temporary storage. This requires shipment of huge amounts of radioactive solids and liquids by rail and road over many thousands of miles. It is inconceivable to think that all this transfer will occur without mishaps and spills. Liquid spills can, of course, seep into the water table and possibly into potable water supplies. Such spills must be temporarily contained by the methods discussed in later sections. 

Year-to-year variations in climate can also drive temporary imbalances in N supply and demand, particularly in water-limited systems. We evaluated this process by modifying the model above (Vitousek and Field, 1999) to include water as a resource—making production, decomposition, and losses all constrained ectuiva-lently by water supply. We ran the model with constant but low... 

You must have a temporary or permanent (water mains) water supply, of suflScient volume, duration, and pressure, as soon as combustible materials accumulate. 

It dissolves in dilute acids (in rainwater that is used as public water supply, this causes temporary hardness). It is a raw material in the Solvay process and is also used in manufacture of lime (CaO), cement, and glass. 

Care must also be taken in terms of routing cables and the provision of temporary electrical supplies to ensure that they are kept free from water and plant/ vehicle movements. 

Figure 4 shows an example water system quantity restoration curve having a temporary 40 % reduction and a permanent 20 % reduction. This may result from an earthquake severely impacting water supply such as ground water wells, aqueducts, or other sources. In this example a 40 % or greater conservation is needed between times to and tj, time of earthquake strike and time when temporary SES is removed, respectively. At time ti an additional 20 % of water supply is restored, but the community must now adjust to a permanent 20 % loss in water supplies. Restoration curves similar to... 

Hundreds of thousands of touring recreational vehicles, caravans and mobile homes, together with pleasure boats of all types and sizes, rely on onboard tanks for personal water supply. There is a correspondingly large number of temporary water users, such as construction sites, camps in remote areas, fishing boats, and so on, all needing a supply of water that is sanitary, and remains so for as long as needed. 

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