Spacing between equipment

An important aspect of moderation concerns the use of space between equipment items. Blast overpressure and concentrations of toxic gas from releases fall off exponentially with distance. Inherent safety suggests that it is better to protect systems from the effects of an explosion by moving them apart from one another than by putting a blast wall between them. If equipment items are spaced well apart from one another, there is also less risk of a confined vapor cloud forming with its potential for a very destructive explosion. 

The minimuin spacing between equipment should be set early on in the design. These distances are set for safety purposes and should be set with both local and national codes in mind. A comprehensive list of the recommended minimum distances between process equipment is given by Bausbacher and Hunt [5]. The values for some basic process equipment are listed in Table 1.11. 

The spacing between equipment is very restricted. It is hard for workers to get away from noisy locations. Hence noise management and control often plays an important role in the design of a facility— particularly with regard to layout. 

The temperature in the ceU is 40°C. Most electrolyte ceUs are equipped with 24 anodes spaced approximately 10 cm apart, center to center 25 cathode starting sheets are used, one at each end and others evenly spaced between the anodes. Current density is typicaUy 15 mA/cm of cathode area ceU voltage ranges from 0.30 to 0.70 V, and a current efficiency of 90—95% is usuaUy realized. 

Equipment. The standard equipment in magnesium foundries consists of large stationary brick-lined reverbatory furnaces which can hold up to 10—15 t of molten magnesium. Reverbatory furnaces are furnaces in which heat is suppHed by burning a fuel in a space between the reactants and the... 

Commonly used heat-transfer surfaces are internal coils and external jackets. Coils are particularly suitable for low viscosity Hquids in combination with turbine impellers, but are unsuitable with process Hquids that foul. Jackets are more effective when using close-clearance impellers for high viscosity fluids. For jacketed vessels, wall baffles should be used with turbines if the fluid viscosity is less than 5 Pa-s (50 P). For vessels equipped with cods, wall baffles should be used if the clear space between turns is at least twice the outside diameter of the cod tubing and the fluid viscosity is less than 1 Pa-s (10... 

A vertical cylindrical, and mechanical agitated pressure vessel, equipped with baffles to prevent vortex formation is the most widely used fermenter configuration. The baffles are typically one-tenth of the fermenter diameter in widtli, and are welded to supports tliat extend from the sidewall. A small space between the sidewall and the baffle enables cleaning. Internal heat transfer tube bundles can also be used as baffles. The vessels must withstand a 45 psig internal pressure and full vacuum of -14.7 psig, and comply with the ASME code. 

Users are warned that an ordinary spring loaded safety relief valve will not open at its set pressure if back pressure builds up in the space between the valve and rupture disk. A specially designed valve is required, such as a diaphragm valve or a valve equipped with a bellows above the disk. 

Space within 5 ft of any edge of such equipment, extending in all directions. Space between 5 ft and 8 ft of any edge of such equipment, extending in all directions. Also, space up to 3 ft above floor or grade level within 5 ft to 25 ft horizontally from any edge of such equipment. ... 

Starting with the boiler(s), these will be set out giving due consideration to space between boilers and other items of plant in order to give adequate access to all equipment, valves and controls for operation and maintenance. For small- to medium-sized boilers 1 meter may be considered a reasonable space between items of plant where access is required. With large boilers (including watertube), this may be increased up to 3 m. The width of firing aisle will be dependent upon the size and type of boiler. 

Where gas or oil appliances are used for heating and installed within the heated space, between 70 per cent and 90 per cent of the total energy content of the fuel input will be converted into useful heat. Table 27.15 gives particulars of some gas-fired equipment types and Table 27.16 gives similar details for some oil-fired heaters. The first three types of equipment detailed in Table 27.15 and the first two in Table 27.16 are usually used for local warming of individuals rather than to provide a particular temperature throughout the space. 

It has been shown in Chapter 29 that the set of vectors of the same dimension defines a multidimensional space S in which the vectors can be represented as points (or as directed line segments). If this space is equipped with a weighted metric defined by W, it will be denoted by the symbol S. The squared weighted distance between two points representing the vectors x and y in is defined by the weighted scalar product ... 

Many companies, as well as industry insurers, trade associations, and standards organizations, have developed specific criteria for spacing between plants, buildings, equipment, and property lines. These criteria are meant to reduce the impact of explosions or fires on major equipment and facilities, including adjacent units and buildings. Table 1.2 illustrates the wide variations of spacing criteria that are suggested. 

New tank systems are also equipped with leak monitoring devices that take advantage of the double-walled construction. Leakage can be reported in real time and more accurately using these detection devices, which include water- or product-sensitive probes, or pressure detection devices if the space between the two walls is designed to remain under vacuum. 

Canyon structure for containment of process equipment, which would be installed and replaced remotely by overhead cranes. This arrangement is most cost effective in that it provides for maximum use of building space since there is no need for space between process equipment Failed equipment can be replaced in less than one day and is then moved to separate maintenance shops within the canyon structure for decontamination and repair. 

The maximum loss concept must also be considered. Some companies place a limit on the maximum loss that can be expected if a fire or explosion occurs. This means that only a certain amount of equipment can be placed in any given area, and that it must be physically separated from other areas. This can be done by providing fire walls, wide spaces between areas, and other fire-localizing designs. 

Separation Distances for Equipment Primarily spacing between pieces of equipment in the same unit and spacing between that equipment and the edge of the unit... 

In addition to fire protection considerations, access for maintenance activities must be provided above, below, and between equipment. Locate equipment subject to frequent maintenance and cleaning close to unit boundaries for ease of access. Lifting arrangements for pumps, heavy valves, and other equipment should be considered in spacing and layout of the unit. 

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