Off-line cleaning

As a result, there is a growing trend to off-line clean reverse-pulse filters by using bags with multiple compartments. These sections allow the outlet-gas plenum serving a particular section to be closed off from the clean-gas exhaust, thereby stopping the flow of inlet gas. On the dirty-side of the tube sheet, the isolated section is separated by partitions from the neighboring sections where filtration continues. Sections of the filter are cleaned in rotation as with shaker and reverse-flow filters. 

The on-line approach shows high efficiency and sensitivity. However, off-line cleaning or replacement requirements of the interface result in limited operational time. On the other hand, problems have been reported with the off-line approach too. The essentially arbitrary collection of fractions (spots) clearly offsets the high resolution of the separation. Other problems may arise from the incomplete deposition of the analyte in the form of drops onto the target, which in turn results in a substantial fraction of the analyte being present in the next deposited drop. 

In some circumstances, off-line cleaning or periodic cleanup programs may also be necessary. 

Off-Line Cleaning of Calcium/lron/Silica Deposits... 

In order to maintain or restore efficiency it is often necessary to clean heat exchangers. Methods of cleaning may be classified into two groups on-line and off-line cleaning. 

There are many specialist companies with experience in off-line cleaning of heat exchangers and it could be extremely beneficial to call upon their expertise to... 

It is valuable to provide connections on the cooling water system, that may be used for flushing to dislodge any accumulations of deposits that might occur. The opportunity to isolate heat exchangers by the inclusion of bypass systems, must be included so that off-line cleaning can be carried out without the need to shut down whole sections of the total cooling water circuit. 

The indirect methods for the determination of anions by on-line precipitation using A AS are shown in Table 7.1. It can be seen that methods with a dissolution step generally have much lower sampling frequencies than those without dissolution. One has to remember, however, that the filters have to be cleaned periodically if the precipitates are not dissolved within each cycle. Therefore, the differences in real sample throughputs will not be that significant if the time for the off-line cleaning of filters is taken into account. 

Off-line cleaning frequency varies between once a week to once a month or more. The following chemicals are used both for in-line and off-line cleaning washes ... 

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