Manhole

Chlorine is stored and transported as a Hquefied gas in cylinders of 45.4-kg or 68-kg capacity that are under pressure and equipped with fusible-plug rehef devices. Quantities in the range of 15 to 90 t are transported in tank cars having special angle valves on the manhole cover on top of the vessel. Tank barges of the open-hopper type having several cylindrical uninsulated pressure vessels are used for amounts ranging from 600 to 1200 t. Road tankers are used for capacities of 15 to 20 t. 

A number of flume designs have been created specifically for use in partially fiUed circular conduits such as sewers. These are available in molded fiber glass and can be lowered through a manhole if required. As with all open-channel head-area meters, flumes must be sized to prevent submergence of the restriction. 

Storage areas for maintenance, janitorial, and other service organizations must be provided. Safety items such as fire extinguishers, firehose cabinets, safety hoops on permanent ladders, guard rads, shielding for acid pumps, clearance for electric panel boards, etc, are needed. Manholes and cleanouts for sewer pipes within the facility as well as in the landscape and parking areas should be provided. 

For low pressure pipelines that have ports open to the atmosphere, eg, sewers or closed effluent culverts, samplers are designed to sample through manholes. In a typical system, the Hquid is lifted through a suction line into the sampling chamber under vacuum. When filled, the vacuum shuts off, and the sample drains into a sample jar. A secondary float prevents any Hquid from reaching the vacuum pump. The suction line then drains by gravity back to the source. 

Fig. UW-13.2. UA-4S to 52. UA-SS. Fig. UA 48. Appendix S Bolted flange. Spherical cover UA-6 Manhole cover plate. UG-11. UG-46 Flued openings. UG-32. UG-38. Fig. UG-38 Yoke. UG-11...

The vessel cover is free of drive components, allowing space for additional process nozzles, manholes, explosion venting, etc., as well as a temperatrrre lance for direct, continrrorrs prodrrct-temperatrrre... 

The distance between trays Zt should be larger than h, sufficient so that (1) the streamers of dispersed hquid from the holes break up into drops before coalescing into the layer of liqmd on the next plate, (2) the linear velocity of continuous liquid is not greater than that in the down out to avoid excessive entrainment, and (3) the tower may be enterea through handholes or manholes in the sides for cleaning. 

While two operators were charging penicillin powder from fiber drums into a reactor containing a mixture of acetone and methanol, an explosion occurred at the reactor manhole. The two operators were blown back by the force of the explosion, and were covered with solvent-wet powder. 

Using a closed charging system rather than pouring dry powders into flammable solvents directly via an open manhole... 

An operator had tested dryer samples on a number of occasions. After the last sampling, he closed the manhole cover, put the dryer under vacuum, and started rotation of the dryer. A few minutes later an explosion and flash fire occurred, which self-extinguished. No one was injured. Investigations revealed that after... 

Provide ground indicator with interlock to prevent manhole opening if ground connection to solids container is faulty... 

NFPA 328 Recommended Practice for the Control of Flammable and Combustible Liquids and Gases in Manholes, Sewers, and Similar Underground Structures, 1992 edition. National Fire Protection Association, Quincy, MA. 

The assessor should determine whether any serious effort is being undertaken by the toller to examine all tasks in detail to identify possible exposure risks, for example, is opening of a tank lid manhole a potential health hazard with certain chemicals ... 

As an example. Fig. 20-7 shows potential and protection currents of two parallel-connected 750-liter tanks as a function of service life. The protection equipment consists of a potential-controlled protection current rectifier, a 0.4-m long impressed current anode built into the manhole cover, and an Ag-AgCl electrode built into the same manhole [10,11]. A second reference electrode serves to control the tank potential this is attached separately to the opposite wall of the tank. During the whole of the control period, cathodic protection is ensured on the basis of the potential measurement. The sharp decrease in protection current in the first few months is due to the formation of calcareous deposits. 

Packed bed heights typically vary from 20 ft to 30ft. Many times the location of manholes to provide access to the redistributor will determine the packed depth. Whenever more than 15 theoretical stages are required in one packed bed, good liquid distribution is critical. ... 

Historical data on similar vessels and fractionation towers can best be used by correlating the costs of this equipment vs. weight. Many methods can be found in the literature for estimating the weight and costs of vessels and fractionators (References 8. 9, 10, and 11). Make sure the estimated weight is complete including skirt, ladders and platfonns, special internals, nozzles, and manholes. 

Infiltration The seepage of groundwater into a sewer system, including service connections. Seepage frequently occurs through defective or cracked pipes, pipe joints, connections or manhole walls. 

In cases where bellows failure would release flammable, toxic or corrosive liquids through the vent, a short nipple and elbow should be used to direct leakage to an open funnel which is piped to grade and ties into a catch basin or manhole with a sealed inlet connection. 

The area below the stack and windbreaker is paved with concrete, surrounded by a 200 mm curb, and graded to a central drain point from which a drain line is routed to a manhole in a vented section of the oily water sewer. The water inlet should be sealed and the manhole should be located at least 15 m from the windbreaker. 

In categories (1) and (2), the manhole receiving effluent seal water should be located at least 15 m from the windbreaker. 

Vacuum Pressure-V acuum Relief Manhole Cover Pressure Safety Valve ... 

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