Drain system

Prior to moving the rig and all auxiliary equipment the site will have to be cleared of vegetation and levelled. To protect against possible spills of hydrocarbons or chemicals the surface area of a location should be coated with plastic lining and a closed draining system installed. Site management should ensure that any pollutant is trapped and properly disposed of. 

Filtration installations include wrapping the trench of a pavement-edge drain system to prevent contamination of the underdrain placement behind retaining walls and bridge abutments to prevent contamination of the sand blanket placed against the stmcture to allow dissipation of pore pressures in order to avoid failure of the stmcture as silt fences to allow surface mnoff from a site while retaining the soil suspended in the mnoff and on earth slopes beneath larger stone or other overlay materials to prevent erosion of the slope as water escapes from the interior of the slope. 

In addition to the information presented in this chapter, refer to Chapter 3, Equipment Configuration and Layout, for further discussions on shared vent and drain systems. 

The use of a drain system permits the quick construction of a collection/removal system which also serves as a barrier for leachate from large, shallow sites. At the Sylvester hazardous waste site in Nashua, New Hampshire, a groundwater interception and recirculation system was installed as a method to retard further spread of the leachate plume until a remedial cleanup action could be implemented. The system was operated for 1 year until a containment wall and cap were constructed over the 20-acre site (McAneny, 1985). 

Usually, the closed liquid drain header is run as a separate line to the drum and provided with a high level cut-off valve with local manual reset. In some cases the closed drain system is segregated into a number of subheaders, as described earlier. Hydrocarbon liquids may be bypassed around the drum through a connection from the closed drain header directly to the pumpout pump suction, provided that the liquid can be routed to a safe disposal location, considering its vapor pressure and temperature. Emergency liquid pulldown connections, if provided, are routed to the blowdown drum via the closed drain header. 

Another common problem area is having open and closed drain systems tied together. Liquid which drains from pressure vessels flash at atmospheric pressures giving off gas. If this liquid flows in the same piping as open drains, the gas will seek the closest exit to atmosphere it can find, causing a potential fire hazard at any open drain in the. system. 

Many accidents have occurred where gas has migrated through the drain system to an unclassified area where welding, or other hot work, was being performed. See Chapter 15. 

Vessel drain systems can be very dangerous and deserve careful attention. There is a tendency to connect high-pressure vessels with low-pressure vessels through the drain system. If a drain is inadvertently left open, pressure can communicate through the drain system from the high-pressure vessel to the low-pressure vessel. If this is the case, the low pressure vessel relief valve must be sized for this potential gas blowhy condition. 

Open, gravity drains should not be combined with pressure vessel drain systems. The gas flashing from vessel liquids may exit an open drain system at any point and create a hazard. 

On open drain piping leaving buildings, a liquid seal should be installed as further protection to assure that gases flashing from liquids from other locations in the drain system will not exit the system in the building. 

The elevation of gravity drain systems must be carefully checked to assure that liquids will flow to the collection point without exiting the piping at an intermediate low point. 

Condenser Controls. .Miscellaneous (Condensing System). Circulating Water. System. Condensate Sysrem. . Pumpa, Piping and Valves. .Low/Tnter. Press- Heater/Oeaerators 3350-3352. .Polishers/Chemical Addle Ion 3360-3399. .Miscellaneous (Condensate System) 3901-3999. Feedwater System 3501-3509. Heater Drain Systems 3520-3529. Entractlon Steam. Electrical. Auxiliary Systems. .Service Water (Open System)... 

Heavy-gauge brass traps are also available, sometimes on special order. They deliver quite good service. For most uses, however, plastic drain systems seem to work best. 

Subsurface drains include any type of buried conduits that convey and collect aqueous discharges by gravity flow (Figure 16.11). Water collected in a storage tank or a collection sump is then pumped for further treatment. Filters are usually needed in drain systems to prevent fine particles from causing clogging. 

There are three common methods for groundwater collection using pumping systems a well point system, a gravity drain system, and in combination with injection wells. 

The gravity drain system is most effective when circumstances are suitable to gravity flow, the water table is less than 3 m and the contaminant is less than 9 m below the surface. 

It will have a slope or drain system to permit removal of leaks, spills, and precipitation, and contain provisions for such accumulation to be removed. 

Open drain ports should be avoided and separate sewage and an oily water drain system should be provided. 

Select the hollow cathode lamp to be used, and install it in the instrument. Your instructor may wish to demonstrate the lamp installation first. Also, check the mixing chamber drain system to be sure it is ready. 

A drainage system includes a containment system using solid, impermeable floors with perimeter features (curbing, floor slope, or trenches) to limit and control the spread of liquids and a collection system (floor drains or trenches, catch basins, sumps, piping, and manholes) to direct the liquids into a gravity drain system that routes them to an appropriate location out of the unit. 

A more specialized algorithm has been proposed by Liu for the simulation of rigid free-draining systems with an equal friction coefficient and bead mass m for every bead. The displacement in Liu s algorithm is given by... 

Doyle et al. [23] have proposed a similar stochastic method of evaluating the stress in Liu s algorithm for rigid free-draining systems. The stochastic stress is given in this algorithm as... 

Bearing housings for pressure-lubricated hydrodynamic bearings shall be arranged to minimise foaming. The drain system shall be adequate to maintain the oil and foam level below shaft end seals. 

Dock drainage. Federal regulations require that free oil be removed from deck drainage prior to disposal. It is extremely difficult to predict an oil drop size distribution for rainwater or washdown water collected in an open drain system, and regulations do not define what size droplet is meant by free oil. 

Thomson s nitrator (See Fig, which is a copy of Fig given in Ref 2) is a shallow earthenware pan, 3.5 ft diam, 10" deep at the sides and 12 deep at the center, where a run-off cock is located. The pan has a false bottom of perforated earthenware segments. Four nitrators are usually connected together by lead pipes so as to be worked as one unit. These pipes are also connected, (thru a gage-box) to the mixed acid storage tanks, to the waste acid tanks, and to the drain system. The mixed acid used at Waltham Abbey consists usually of HN03 21.0, HzSO 70.5, HNOz 0.6 HaO 7.9%... 

On a positive note, here the oudet tail pipe is the same size as the valve outlet size and is equipped with a drain system. ... 

Without a method or mechanism to detect a catastrophic, or even a small release from an inner wall, the use of a secondary outer wall is superfluous. A failure in the inner wall will certainly lead to a failure of the outer wall if the failure goes unnoticed and no action is taken. The secondary wall may delay the release, but release would be inevitable without annular space detection. Typical detection mechanisms include gas analyzers or pressure detectors for vapors, conductivity switches for liquids, or weep holes routed to drain systems that are periodically monitored (Prugh, 1992). A purge gas is sometimes used as a detection medium, to reveal a change in contaminants in the purge gas exhaust (CCPS, 1988b). 

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