Gravity draining

Closed drain headers are normally provided for safe drainage of equipment containing severely toxic, corrosive, pollutant or high cost chemicals (e.g., phenol, sulfuric acid, monoethanolamine, sulfur dioxide, catacarb) where there is an appreciable inventory in a number of processing vessels in a plant. The header should be at least 50 mm in diameter, and should be tied into the major vessels and equipment with 25 mm minimum size connections (20 mm is considered adequate for pumps). The header may be routed to a gravity drain drum (with recovery to the process by pump or gas pressurization), or to a pumpout pump returning to the process, or in the case of sulfuric acid, to an acid blowdown drum. 

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. 

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. 

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. 

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. 

High-Silicon Iron Pipe and fittings are cast products of material typicmly conforming to ASTM A518. Nominal silicon content is 14.5 percent, and nominal carbon content is approximately 0.85 percent. This material is corrosion-resistant to most chemicals, highly abrasion-resistant, and suitable for applications to 260°C (500°F). Applications are primarily gravity drain. Pipe and fittings are available under the trade name Duriron . 

Backfill surface, which is normally used to provide a gravity drain to the workings, but often also as access for personnel and materials (synonym drift, meaning (a)) Fractured waste rock deposited into a former opencast mine void (sedimentologically similar to spoil and to gottj)... 

Figure 2.1 A gravity-drained tank with a leak.

For a gravity drain of the pressure tank and electrolyzer as mentioned above, the pump and 3-way valve must be located below the electrolyzer and pressure tank, so that the fluids will drain downward. The reservoir can positioned at any level, since the pump is used to drain it. 

Gravity Drains liquid from the film between two ad(jacent bubbles. 

Unless it is intended to maintain a liquid level in the condenser, all liquid outlet piping should leave the condenser at the bottom and slope toward the reflux drum (or condensate pot) with no high points. This practice is recommended in most cases, and is essential for gravity draining. The condenser in Fig. 15.15c experienced a liquid-removal problem (134) because its outlet was not at the bottom of the condenser. A similar problem has been reported by others (381). 

Leachate collection channels to a sump shall be made. Leachate removal by pumps or by gravity drains to holding tanks. Further treatment facility for the leachate shall also be made at site by physical, biological, or chemical methods. 

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