System flush

Operations that are conducted while the RO system is offline are just as important as on-line operations in keeping an RO system functioning well. Off-line operations covered in this chapter include system flush, membrane cleaning, and membrane lay-up. 

System flushes are typically used when an RO system goes off-line, comes back on-line, and during stand-by mode. The ptnpose of the off-line and stand-by flushes is to rid the feed/concentrate side of the membrane of either high concentrations of feed water species or to stir up materials that may have settled on the membrane during down time and wash them away. The on-line flush (when the membranes come back on line) is to reduce the conductivity in the RO permeate before sending the permeate on to further processing or to the ultimate use. Flush water is typically sent to drain. 

It is important during flush to keep the permeate line wide open to prevent delamination of membranes at the concentrate end of the pressure vessel (see 

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The analysis speed is determined (a) by the ICP or AA system flush-out characteristics and (b) by the mixing and sample-transfer rates of the dilutor. TTie latter can readily be adjusted by increasing the flow-rate of the peristaltic pump tubes. The steady diluted stream can easily be adjusted in order that only a few seconds is required to flush out the previous sample and to set up a steady stable flow. Although peristaltic pumps are... 

Preventive Flush. In systems where rust and dirt are found in the presence of grease and oil, a cooling system flush with a chelator cleaner is recommended. 

Flush the system to remove dust and major debris. Recirculate detergent or alkali cleaner at elevated temperatures to remove grease or oil. Flush and recirculate an acid at elevated temperatures to dissolve any ferrous particles in the system. Flush with water of the same quality as will be used in service. The cleaning procedure shall be validated by making chemical analysis of surface residues. System functional checkout... 

Controlled by the MS-MS software, the PE Series 200-micro LC pump operates iso-cratically using 80% acetonitrileiwater at 40 pl/min. A 50 x 1 mm C18 column (Keystone) is used between the pump and autosampler to provide back-pressure. The syringe/system flush solution is the 80% acetonitrileiwater used as the mobile phase. The autosampler is connected directly to the MS-MS Turboion Spray source. The injected sample volume is 20 pi. 

Leaching Studies. A determination of the adequacy of RO system flushing and a definition of substances that could leach from the system are important to the use of the sampling method. Both of these questions were addressed in these studies. 

A. Preparation of bis(2-Cyanoethyl)phenylphosphine. A 250-ml. three-necked flask is equipped with a magnetic stirrer, a thermometer, a pressure-equalizing dropping funnel, and a reflux condenser with the entire system flushed with nitrogen. To the flask is added under an atmosphere of nitrogen 50.0 g. (0.454 mole) of phenylphosphine (Note 1), 50 ml. of acetonitrile, and 10 ml. of 10N potassium hydroxide (Note 2). An ice-water bath is prepared for immediate cooling of the reaction flask. To... 

A block diagram of the apparatus is shown in Figure 1. The system is constructed to use three sodium chloride anolyte and four sodium hydroxide catholyte concentrations. The starred anolyte compartments refer to separate solutions which have been doped with radiotracer. These solutions are used only for determinations of transport number the nonradioactive brine solutions are used for system flushing and membrane equilibrations. Solutions are selected and pumped into the cell, under computer control, through an all-Teflon pump-valve system. The solutions are heated during these transfers to ensure rapid attainment of experimental temperature in the cell. The brine system is designed to enable the return of radiotracer solutions to their storage vessels after each use. This serves to reduce consumption of radioactive solutions. 

The electrodialysis method uses tanks lined with an insulating layer. From 5 to 30 properly spaced counterelectrodes are surrounded by membranes (Figure 2), which separate the coating bath from the counterelectrode by means of a membrane permeable to the solubilizer Y. A plumbing system flushes the solubilizer out of the counterelectrode compartment (Figure 2). 

Set the column temperature at TC to enhance protein integrity during the run, and turn on the HPLC system, flush columns with 80% of Buffer B at a flow rate of 250 pL. min for 20 minutes. Follow the manufacturer s instructions when using new columns, and carefully monitor the column pressure for any backpressure indicating possible clogging. 

During the fractional distillation, there are some precautions which should be followed. Hydrazine hydrate attacks rubber and cork, so the use of these materials must be avoided in the distillation. It also attacks most kinds of stopcock grease. The distillation is most safely done under nitrogen. Nitrogen should be introduced into the distilling flask, and the system flushed of air for about 15 minutes. Then the rate of nitrogen flow is reduced, and distillation commenced. The product will also attack glass, albeit slowly. It should be stored in 304 or 347 stainless steel. 316 stainless is not acceptable. 

Run time. The 500-hr run clock begins when steady state is attained with full hydrolysate flow. The 500-hr run time applies to normal system operation and therefore includes planned system flush cycles. Unplanned shutdowns and recovery from unplanned shutdowns back to steady-state operation are not counted in the 500-hr run time. 

Vitamin K (phylloquinone), 2, 3 -dihydrophylloquinone, and menaquinones (where n = 4, 5, 6) were extracted fiom milk and infant formula and analyzed on a C,8 column (A = 243 nm, ex 430 nm, em). All compounds were well resolved and eluted in 15 min using a 90/10/0.5 methanol/dichloromethane/methanol (with lOitiM zinc chloride, 5mM sodium acetate, and 5mM acetic acid) mobile phase [344]. Note that this level of salts in the mobile phase could precipitate in various parts of the LC system. Flush the system regularly. The linear working curve extended from 2 to 50 ng/mL with a detection limit of 1.5 ng/mL. The authors noted that this compared favorably to a UV detection limit (at A = 269 nm) of 50 ng/mL. 

Volume reduction of concentrated evaporator bottoms, which may include boric acid wastes, laundry wastes, chemical wastes, and other floor drain wastes, is accomplished in the radwaste volume reduction system. The major components of the system are the crystallizer chamber and recirculation system, condenser, and vacuum pump system. The crystallizer chamber consists of a conical tank and an inner circular baffle to separate solid crystals from a clear recycle stream. Combustible wastes such as clothing, filter cartridges, and wood are volume-reduced in the radwaste incinerator. Solidification of volume-reduced wastes and other low-level radioactive wastes, such as spent resins and contaminated tools, is performed in the cement solidification system. The major components of the cement solidification system include the high shear radwaste mixer, waste dispensing system, flush water recycle steam, cement storage and feed system, and the container handling system. 

The emulsion can become something else — a foam. If the spray nozzles are not properly aimed (and sized) so that they act directly on collections of liquid and not on part surfaces, foam can be generated. Foam is a fearsome enemy in all cleaning systems. Foam is air and chemicals. When foam breaks in tbe rinse vessel by the air being removed, the cleaning chemicals remain on part surfaces as chemical-rich residues. Usually, when foam is noticed within the semi-aqueous process, the operating machine must be shut down and the system flushed with fresh water — else soiled parts will continue to be produced. 

The system includes a positive displacement (PD) metering pump, dilution water piping and a control panel for system logic. The control panel has a 24-hour timer to set cycles. Upon completion of the feed cycle, the system flushes the feed line with at least three pipeline volumes of water. Dilution and flush also run off the timer. This automatic flushing system reduces the risk of exposure to potentially harmful concentrations of chemical, making it much safer than a simple metering pump. 

The phosphate analysis described here is characterized by an analysis time of four minutes, when system flushing is included This is in contrast to the conventional flow injection analysis of phosphate using the molybdenum blue method reported in [2] and [10] These two studies indicate analysis times of 30 and 80 seconds, respectively Several factors play a role in the longer analysis times for the micromachmed system First is the incorporation of a time-based injection technique in the system, as opposed to the volume-defined methods using valves described in [2] and [10] While elimination of the need for an injection valve simplifies the system, time-based injection schemes by... 

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