Water-supply systems tank materials

Biofilm study was carried out in the drinking water supply system DWSS"Yovkovtsy , that supply with water the region of Veliko Tamovo, and in the laboratory model of water distribution system. Some experiments were performed 1) to determine microbiological composition of biofilm samples scraped from mild steel or reinforced concrete s main pipe line and concrete tank of DWSS Yovkovtsy 2) to study biofilm formation process on test pipe from PVC, PE, stainless steel and carbon steel in a laboratory model of drinking water distribution system under flow velocity 0,006 cm/s. 3) to study dynamics of biofilm formation process on polypropylene, the pipe material used during the last years in Bulgaria, in a model water distribution system under flow velocities 0.3 m/s, 0.5 m/s, 0.7 m/s and 1 m/s. 

The next step is to apply a number of loss control credit factors such as process control (emergency power, cooling, explosion control, emergency shutdown, computer control, inert gas, operating procedures, reactive chemical reviews), material isolation (remote control valves, blowdown, drainage, interlocks) and fire protection (leak detection, buried tanks, fire water supply, sprinkler systems, water curtains, foam, cable protection). The credit factors are combined and appHed to the fire and explosion index value to result in a net index. 

Firewater supply sources can be the city public water main, a dedicated storage tank and pumps, or the most convenient lake, river or if an offshore installation the open sea. Brackish or salt water supplies can be used if suitable corrosion protection measures are applied to the entire firewater system if it is planned to be used for an extended life (i.e., grater than five years). If a short life span of the facility is expected, short corrosion resistant materials may be used (i.e., carbon steel, galvanized steel, etc.), provided periodic testing indicates their integrity is still adequate and scale or corrosion particles do not affect operational efficiency. 

Each SCB incorporates a water washdown system to periodically clean inner SCB surfaces that become contaminated. This is accomplished to maintain the working environment as clean as possible to maintain product purity. The system consists of a supply manifold located in Room 114, water supply piping inside of the Zone 2A canyon, nozzles on the top of each SCB, and a drain system that will allow injected water to drain out of the SCB into a collection tank. The system is not permanently connected to a water supply and would only be activated when ail process materials, including radioactive targets, have been removed from the SCB which is to be cleaned. To effect cleaning of the SCB, a pressurized water filled container is connected to the system each time a cleaning operation is desired. The supply of water to a specific SCB is controlled by valves in the supply header. 

Chilled water supply involves a closed circuit. The water flows through a supply header, the users, and a return header to a storage/pump tank. Demineralized water is a typical source. It is added occasionally to replace water lost from the system or deliberately purged to remove contaminants such as process fluids and corrosion products. Storage tank construction is simple. The pressure is essentially atmospheric and the temperature is low. Since water is more corrosive when aerated, the tank may be blanketed, and plain carbon steel construction should be avoided. Lined steel and FRP are acceptable materials of construction. 

Every facility can benefit from a review of its infrastructure. This includes all utilities, entrances/exits, process and production equipment, telephone and data lines, water supply, backup power systans, process controls, hazardous material storage tanks and pits, fire alarm systems, and sprinkler systems. Making a list of all infrastructure details is helpful when evaluating security vulnerability, as well as such mundane tasks as budget analysis, routine and preventive maintenance, and personnel responsibilities. 

Pumps are required in the feed system either to transfer product within the feed systan or to supply product to the atomizer. The pumps in the spray-dryer feed system are sized and selected for each application depending on the type and properties of the feed material and also depending on the atomizer incorporated in the feed system. When rotary atomizers or two-fluid nozzles are used, low-pressure pumps are also usually used. When pressure nozzles are employed, high-pressure pumps are required [34]. Various types of pumps are used because of the variety of feed materials that are encountered (see Table 52.6). A water tank for dryer startup and shutdown is mounted on the atomizer feed pump. 

Most dry chemical feed systems have several mjgor parts. Dry chemicals are delivered in bulk or packaged in bags or drums. Enough inventory is stored on-site to ensure an uninterrupted supply. Chemicals are then loaded into hoppers that supply the feeder. In some smaller treatment plants, the bag or drum is used as the hopper. The material is metered from the feeder into a solution tank, where it is mixed with water. The solution is then dispersed into the water stream (sometimes the solution is held in a day tank first), where it is thoroughly mixed. A typical dry chemical feed system is shown in Figure 5-1. 

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