Circulating lubrication

In a forced-feed lubrication system, a pump circulates lubricating oil through a cooler and filter to a distribution system that directs the oil to all the bearings and crosshead shoes. Figure 11-23 is a schematic of a typical system. The details of any one system will vary greatly. Major components and considerations of a forced feed lubrication system are as follows ... 

Figure 3-26. Circulating lubrication. (By permission, H. P. Hummer and W. J. Ramsey, Bulletin SD 752, O T, Durametallic Corp.)...

Refers to the ability of an oil to separate from water, as determined by test method ASTM D 1401 or D 2711. Demulsibility is an important consideration in lubricant maintenance in many circulating lubrication systems. Refer to Demulsifier and Dynamic Demulsibility. 

The exchangers used to cool the gas and the circulating lubricating oil are of standard construction and usually operate on plant cooling water. Compressor cylinders frequently also are jacketed and cooled. Water used in the jackets should be clean, and frequently its source is something other than plant cooling water. One must be careful not to cool the gas enough to condense water in the cylinders. At startup, it may even be necessary to heat the cylinders. 

Foam Inhibitors. Methyl sihcone polymers of 300-1000 mm /s(= cSt)) at 40°C are effective additives at only 3—150 ppm for defoaming oils in internal combustion engines, turbines, gears, and aircraft appHcations. Without these additives, severe churning and mixing of oil with air may sometimes cause foam to overflow from the lubrication system or interfere with normal oil circulation. Because sihcone oil is not completely soluble in oil, it forms a dispersion of minute droplets of low surface tension that aid in breaking foam bubbles. 

Nuclear Radiation Effects. Components of a nuclear reactor system that require lubrication include control-rod drives, coolant circulating pumps or compressors, motor-operated valves, and fuel handling devices, and, of course, are exposed to varying amounts of ionising (14). 

The frame lubrication system circulates oil to the frame bearings, connecting rod bearings, crosshead shoes, and can also supply oil to the packing and cylinder lubrication system. Splash lubrication systems are... 

In a batch reaction plant, an exothermic reaction was cooled by water circulating in a jacket. The circulating pump failed and the reactor went out of control causing a violent explosion. A low flow alarm was present but was inoperable. A critical pump bearing had not been lubricated during maintenance, and the collapse of the bearing had led to the pump failure. 

Fluid at approximately 60% of discharge pressure is circulated through the bearings and over the rotor tor cooling and lubrication and returns through the hollow shaft to suction pressure. 

Lubricate Stuffing Box By Circulating Water or Clear Solution thru Connections x"a"Y". 

Lubrication Circulating Good cooling of contact faces 3-26... 

Forced lubrication is recommended for large-horsepower drives, heavily loaded drives, high-speed drives, or where splash and disk lubrication cannot be used. An oil pump—capacity about 1 gal/min—supplies a continuous spray of oil to the inside of the lower span of chain. The circulation of the lubricant aids in the dissipation of heat and results in a well-lubricated, cooler operating device. 

In positive lubrication systems, a gear-type pump is normally used to provide positive circulation of clean oil within the compressor. In some cases, the main compressor shaft directly drives this pump. In others, a separate motor-driven pump is used. 

It is generally tme to say that, as speed increases, the oil viscosity decreases, that is, if hydrodynamic conditions exist. Relatively low viscosity oil will allow the oil to spread rapidly over the tooth surfaces before meshing and, in the case of forced lubrication, ease circulation. In the case of bath lubrication, it will eliminate the oil drag effect. 

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