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ARNOLD, K. (1999). Design of Gas-Handling Systems and Facilities (2nd ed.) Episode 2 Part 12

Tham khảo tài liệu 'arnold, k. (1999). design of gas-handling systems and facilities (2nd ed.) episode 2 part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 512 Design of Gas-Handling Systems and Facilities For buildings of 1 000 ft3 or less such as a typical meter house API RP 500 defines the building as being adequately ventilated if it has sufficient openings to provide twelve air changes per hour due to natural thermal effects. Assuming the building has no significant internal resistance and that the inlet and outlet openings are the same size and are vertically separated and on opposite walls the required free area of the inlet or outlet is A 7- --7 - 177 17 - X 1 200 H Tj -T2 TJl 2 where A free area of inlet or outlet openings includes a 50 percent effectiveness factor ft2 Vol volume of building to be ventilated ft3 T temperature of indoor air R T2 temperature of outdoor air R FT height from the center of the lower opening to the Neutral Pressure Level NPL ft NPL is the point on the vertical surface of a building where the interior and exterior pressures are equal. It is given by 1 A A2 2 T T2 where H vertical center-to-center distance between Aị and A2 ft Aị free area of lower opening ft2 A2 free area of upper opening ft2 For example assume a building with inside dimensions of 8 ft wide 10 ft long and 8 ft high an outside temperature of 70 F inside temperature of 80 F Aị A2 and the vertical center-to-center distance between A and A2 of 6 ft. The height from the center of the lower opening to the NPL is H - 2.97 ft 1 540 530 Equation derived from 1985 ASHRAE Handbook of Fundamentals Chapter 22 assuming an air change every five 5 minutes. Refer to the ASHRAE Handbook. Chapter 22 for additional information on naturally ventilated buildings. Electrical Systems 513 Therefore the minimum area required is A __ 8 10 8 1 200 2.97 10 540 2 - 2.27 ft2 for both the inlet and the outlet GAS DETECTION SYSTEMS Combustible gas detection systems are frequently used in areas of poor ventilation. By the early detection of combustible gas releases before ignitible concenừation levels occur corrective procedures such as .