Water spray systems applications

Water spray systems for hydrocarbon facilities are routinely specified because of the rapid application means the system can provide and the excellent heat absorption a water based system represents. Water sprays are also used when passive fire protection measures (i.e., fireproofing, spacing, etc.) cannot practically be utilized. The key to providing an effective system is to ensure the surfaces to be protected receive adequate water densities and that the arrangements to activate the system are equally fast acting. By far the highest... 

American Petroleum Institute (API), Publication 2030 Guidelines for Application of Water Spray Systems for Fire Protection in the Petroleum Industry. First Edition, API, Washington, D.C., 1987. 

The last two applications, while convenient and initially appealing, require more maintenance and inspection than a simple, ground level monitor. Significant reactive forces can be generated and, therefore, the support structures must be properly engineered. Elevated monitors also require support and hydraulics to be protected by a water spray system if exposed to fires. An elevated monitor is shown in Eigure 7-12. 

Deluge protection can be applied over the entire hazard area with open sprinkler heads located at various floor levels or fixed water spray systems can be applied specifically on the equipment to be protected. Specific water spray application is preferred because it provides better equipment cooling and reduces the water wasted due to wind and fire draft. 

The quantity of flammable liquids or gases or heated combustibles can be indicative of the need for fixed water spray fire protection. Table 8-4, developed from FM Data Sheet 7-14, suggests quantities of flammables where fixed water spray fire protection should be considered based on one insurance provider s guidance. Some company internal guidelines and practices allow up to 5,000 gal (18,927 I) in the largest vessel before water spray protection is recommended. Additional guidance on fixed fire protection is available in API Publication 2030, Application of Water Spray Systems for Fire Protection in the Petroleum Industry, (API, 1998). 

The required protection may be obtained by active, passive, or a combination of both protection systems. For example, steel support located in a fire exposed area within process unit battery limits may be protected by either a fixed water spray system or the application of fire resistant insulating material to the steelwork or possibly both. Note Passive protection is generally the preferable method for protecting structural steel. 

Fine water spray systems may be potentially superior to CO2 applications and may replace halon environments such as telephone central offices and computer rooms. In the fine spray delivery system, water is delivered at relatively high pressure (above 100 psi [0.689 MPa]) or by air atomization to generate droplets significantly smaller than those generated by sprinklers. Water flow from a fine spray nozzle potentimly extinguishes the fire faster than a sprinkler because the droplets are smaller and vaporize more quickly. Preliminary information indicates that the smaller the droplet size, the lower the water flow requirements and the less chance of water damage. 

API Publication 2030 (1998) Application of water spray systems for fire protection in the petroleum industry. 2nd ed. (American Petroleum Institute). 

Normally where it is necessary, fireproofing is preferred over water spray for several reasons. The fireproofing is a passive inherent safety feature, while the water spray is a vulnerable active system that requires auxiliary control to be activated. Additionally the water spray relies on supplemental support systems that may be vulnerable to failures, i.e., pumps, distribution network, etc. The integrity of fireproofing systems is generally considered superior to explosion incidents compared to water spray piping systems. The typical application of water sprays in place of fireproofing is for vessel protection. 

Exposure protection systems provide protection by the application of water to structures and equipment for the anticipated duration of the exposure fire. Water spray curtains are generally less effective than direct application due to unfavorable conditions such as wind, thermal updrafts, and inadequate drainage. Extinguishing agents such as CO2 or dry chemical agents are not able to provide this type of cooling. 

Fire resistant insulating material can provide passive protection for both vertical and horizontal structural steel members. The level or rating of fire resistance should be consistent to the expected fire duration. Where only fire resistant insulating material will be used, the material and its installation system should be specified to have a 2- to 3-hour fire rating (UL 1709). In applications using a combination of fixed water spray or sprinkler protection and fire resistant insulation, a 1- to 2-hour fire rating (UL 1709) is frequently specified for the fireproofing. 

Use of manual fire monitors or area coverage water spray or deluge systems are typically sufficient for the fire protection of heat exchangers. However, where exchanger support saddles exceed 12 in (30 cm) in height, the supports should be protected by either water spray at a density of 0.3 gpm/ft (12 Ipm/m ) or application of fire resistive material. 

Fixed active fire protection systems incorporating both water spray and foam application... 

NFPA 214 provides specific guidance regarding fire protection of cooling towers including recommended water spray application rates. The detailed design of fixed fire protection systems for cooling towers should follow the requirements of NFPA 13 or NFPA 15. 

The solvent elimination problem became less of a problem with the commercialization of microbore columns. Hayes et al. (54) studied gradient HPLC-MS using microbore columns and a moving-belt interface. The heart of the system was the spray deposition device designed to be compatible with microbore-column flow rates. Nebulization of the eluent was found to be applicable to a variety of mobile-phase compositions and thus was readily compatible with gradient elution. Figure 13 shows a comparison of UV detection with that obtained with the HPLC-MS system. Applications of this system were demonstrated on water from coal gasification processes. 

A fire suppression system should be provided around the dispenser to protect personnel and vehicles from fire during refueling. Actuation shall be provided both by sensors automatically and through the use of a manual switch. LP gas tanks that can be exposed to fire should have water spray fixed systems to prevent the tanks from failure due to over-temperature. The direct application of water in the form of a spray can also be used to control unignited gas leakage. 

Gas-continuous impinging streams with a liquid as the dispersed phase has wide application, such as in the combustion of liquid fuel droplets, absorption, water-spray cooling of air, etc. [9]. In such systems the dispersity of liquids plays a very important role affecting heat and mass transfer rates, because it influences both the interface area and the mean transfer coefficient. Wu et al. [68] investigated the influence of impinging streams on the dispersity of liquid. 

Figure 2. Linear chromatograms for the separation of bromophos-ethyl and dimethoate on an HPTLC pre-coated plate silica gel 60 Cleft) and an HPTLC pre-coated plate RP-18 fright) (solvent system on silica gel 60 n-heptane/acetone 65/35 on RP-18 acetone/water 80/20 application from left to right—(1st band) bromophosethyl (2nd band) dimethoate (3rd-5th band) mixture migration distance 5 cm applied quantities 0.75 fiL =-- 750 ng detection spraying with PdCl2 in ethanol heating to 120°C)...

In addition to the excellent performance properties and the reduction of solvent carriers, waterborne epoxy adhesives were found to have processing advantages. They could be easily applied by conventional coating systems (spray, roller, etc.) they were less hazardous to workers due to lower dermatitis potential and inflammability ventilation equipment costs could be reduced and application equipment could be easily cleaned with soap and water. In many applications, these processing advantages became the primary market drivers for waterborne epoxy adhesives as alternatives to more conventional adhesives. 

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