Pumps troubleshooting

Another option is the dry-pit design (Fig. 7c). This pump is installed in a dry pit and coimected to a weU via a pipe. Because the dry pit is usually dug out wider than the wet pit, Tenough room is available for pump maintenance, troubleshooting, and repair without pulling the pump to the surface for servicing. 

Troubleshooting Centrifugal Pumps and their Systems Ron Palgrave ISBN 185617 3917 [2003)... 

Too few people eonsider the equipment with the seal seleetion. In most eases, poor equipment will give poor seal performanee, regardless of the seal or arrangement ehosen. Also, beware that different pumps with the same shaft diameter and TDH may present different sealing problems. (Note These same eonsiderations may be used for troubleshooting.)... 

Maintenance and production records, along with the used lean and rich glycol analyses, can be very helpful to the troubleshooter. A history of filter element, carbon, tower packing, and firetube changeouts can sometimes be very revealing. The frequency of pump repairs and chemical cleaning jobs is also beneficial. With this type of knowledge, the troubleshooter can quickly eliminate and prevent costly problems. 

Troyan, J. E., series Hints for Plant Startup, Chemical Enginnering, Part I—Troubleshooting New Processes, November 14, 1960, p. 223 Part II—Troubleshooting New Equipment, March 20, 1961, p. 147 Part III—Pumps, Compressors, and Agitators, May 1, 1961, p. 91. 

Establish control charts of instrumental performance. Day-to-day variations in pump flow rate, relative response factors, absolute response to a standard, column plate counts, and standard retention times or capacity factors are all useful monitors of the performance of a system. By requiring that operators maintain control charts, troubleshooting is made much easier. The maintenance of control charts should be limited to a few minutes per day. 

Control can be exercised by the operator in the control roam on the well chokes and manifold divert valves (although this is normally handled by the HOC), start/atop of the oil shipping pumps, utility equipment, switching valves, gas plant feed valves, gas compressor start/stop and emergency shutdown of any production train or the entire GC. Since the closed loop process control is performed by local pneumatic instruments, all set point changes and controller troubleshooting must be accomplished locally. 

B. Troubleshooting and Mounting a Mechanical Pump, it will be noted in Fig. 6.2 that gas from a rotary pump is exhausted through an immersed flapper valve. For this valve to make a good seal it must be covered with oil. One common cause of the loss of ultimate vacuum performance in these types of pumps is a low oil level, and this should be the first item to be checked when a pump is not performing well. A telltale sign of low oil is a change in the sound of the pump. 

Such a survey becomes a combination of an annual inspection and a troubleshooting exercise. The fact is that operating practices change with time the production process may be adjusted or new sections of cooling systems are added to the main plant, or pumps, heat exchangers, and other items of equipment are periodically replaced. The personnel also change. 

The first step is to locate the point of the pressure increase. Since most problems are column problems, we can simplify our task by eating the elephant one bite at a time. Remove the column from the system and turn on the pump. If the pressure problem goes away, it was in the column. If not, it s in the system leading up to the column. I ll deal here only with the column pressure problems, the system problems will be dealt with in Chapter 10 on troubleshooting. 

Reverse osmosis skids are typically contained within a frame of galvanized or urethane-coated steel. Skids should be designed for easy access for monitoring and maintenance. Access to controls, instruments, valves, the pump and motor, and membranes is essential. Access to the permeate from each pressure vessel is often overlooked. Without such access, profiling and probing used to troubleshoot poor performance is not possible (see Chapter 14.7). 

The development of gradient systems, available with both feed-forward and feedback control systems, is an important capability of the pumping system. In order to troubleshoot problems with the gradient system, it is valuable to have a feed-back control gradient system. 

Records also help prevent mistakes, such as introducing water into a silica column, or precipitating buffer in the system by adding too much organic solvent. Many analysts occasionally modify their HPLC systems for a variety of reasons. Reliable records are the best way to ensure that a modification does not introduce problems. For problems relating to pumps, detectors, automatic samplers, and data systems, instrument manuals provide suitable troubleshooting guides. 

Figure 6-15 Cross-sectional view of a dual-piston reciprocating pump. (From Walker JQ, Jackson MT Jr, Maynard JB Chromatographic systems Maintenance and troubleshooting, 2nd edition, New York Academic Press. 1977.)...

If initial SST fails, the analyst should stop the sequence immediately, diagnose the problem, make necessary adjustments or repairs, and re-perform SST. Analysis of actual samples should commence only after passing all SST limits, not only the failed criteria. Most SST failures are traced to problems from the autosampler, pump, column, or mobile phase (see Chapter 10 on troubleshooting hints). If one of the interspersed SSS injections fails, data from all samples after the last passing SSS become invalid and must be repeated.15... 

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