Flushing, line

Pumps shall use throat bushings, wear rings, impeller balance holes and/or flushing line arrangements for the following ... 

Auxiliary process fluid piping inclndes vent and drain lines, balance lines, product flushing lines, and lines for injection of external fluid. 

Dry all flushed lines with dry nitrogen for a minimum of hours PF/Operations team ... 

Pressure. The location of pressure sensors in evaporative crystallizers also affect their reliability. If the operating pressure measurement is made in the vacuum line or condenser, it will be affected by the evaporation rate of the solvent and pressure drop changes due to any incrustation in the lines or mist eliminator. Measurement of the pressure in the vessel headspace circumvents this interaction. The sensor should be equipped with a solvent flush line to ensure that incrustation does not distort the measurement. 

It is best to water-flush (or gas-blow Sec. 11.1) the water circulation lines before a prestartup wash. During flushing, lines should be broken at the column inlet to prevent debris from entering the column. For an effective flush, water velocities of 12 ft/s have been recommended (295). During the wash, strainers should be used in the water circuit, especially upstream of distributors or other delicate internals. 

Place dykes around pumps and tanks, cleaning and flushing lines, sewer systems... 

Gland or seal oil is sometimes used to lubricate the faces. More often, the liquid being pumped is used as the lubricant. This lubricant must be clean. If a process change has introduced particulates into the liquid being pumped, the seal on a self-lubricated pump can be damaged. Installation of a small cyclone separator on the seal flush line (i.e., the small line from the pump discharge to the seal) may help. Better yet, obtain a source of clean seal flush liquid. 

Clean or flush line and reduce temperature or pressure as required. 

N building houses the equipment used to sample effluent gases and particulates in the adjacent 116-N air stack. One sample collection device used clean water as the coolant for a condenser. When originally installed, the coolant drain pipe was improperly connected to the nearby 91-cm (36-in.) low-pressure flush line that carried irradiated reactor cooling water from the... 

Pump each mobile phase component at 5 mL/min for 5 min with the instrument purge valve open to flush lines and prime instrument (7). If the instrument is not sufficiently primed, retention times may be outside their monitoring window or chromatographic peaks may be absent. 

A seal should maintain its integrity for six years, provided it is operating correctly. Most often seal life is compromised by improper start-up procedures. For example, starting up a pump without venting the seal flush lines to the inner seal on a self-flushed pump may reduce the operational seal life by six months, even though the seal faces have run dry for only a few seconds. 

No," Zip answered. "Those were external flush pumps. Wouldn t want to get tar between them seal faces. Those pumps were flushed with diesel oil or light gas oil. On that kind of pump, the operator needs to adjust the seal flush pressure a few psi above the pump suction pressure. Best to have a little needle valve and a rotometer. Also, you gotta have a pressure gauge after the needle valve on the seal flush line."... 

Failure to fill the seal flush line prior to starting the pump. 

Particulates in the seal flush can scratch the seal faces. I ve never actually encountered this problem myself, but it can be prevented by installing a Centrifix Filter on the seal flush line. 

On one hydrocarbon pmnp, the restriction orifice was omitted from the seal flush line. This greatly increased the pressure on the seal faces. The seal blew out with a large and quite dangerous emission of hydrocarbon vapor to the atmosphere. 

For self-flushed pumps, it is necessary to vent and fill the seal flush lines completely. Otherwise, on starting the pump, there will be no seal flush flow for a second or so, which will materially damage the seal. 

Referring to Fig. 37.1, in addition to valve 1, the valves shown as valves 2 and 3 must also be added. Without valves 2 and 3, the complete seal flush line cannot be filled with liquid. For externally flushed pumps, valves 2 and 3 are not required. 

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