Permanent strainers

Strainers offer a simple method for the protection of pipeline systems, by removing debris such as dirt, swarf, weld sputter, scale and so on. They are simple coarse filters using perforated plate or wire mesh as the filter medium. Strainers fall broadly into two categories temporary strainers and permanent strainers. 

An obvious disadvantage of a permanent strainer of the types just described is the need to shut down the plant flow so that they may be cleaned. Where continuous operation is required in a pipeline service, duplex strainers can be used in an integral unit with the provision to isolate one element at a time for cleaning, or even having multiple strainers in one unit (as shown in Figure 3.6). Individual strainer elements or baskets are then made accessible via cover plates with static seals (usually 0-rings). 

It would appear obvious for startup, and in some cases full-time operation. that a suction strainer or filter is mandatory. The reason for ilic strainer is to keep Junk and pipe scale out of the compressor. Fines from pipe scale and rust will make short work of the internal bore of a cylinder and are not all that good for the balance of the components. In some severe ca.ses, cylinders have been badly damaged in a matter of a few weeks. The strainer should be removable in service for cleaning, particularly when it is intended for permanent installation. Under all circumstances, provision must be made to monitor the condition of the strainer. Much frustration has been expended because a compressor overheated or lost capacity and no one knew if the strainer had fouled or blinded. 

A strainer should be used in the pump suction line temporarily for a centrifugal pump and permanently for the rotary positive displacement pump. For the permanent installations, a Y-type strainer with an austenitic stainless strainer basket should be used. The cross-sectional... 

Permanently installed feed systems can create problems. Some chemicals (such as urea, sugar, NaOH, CaCl2, etc.) tend to weep from valves and flanges. It is particularly important after new gaskets have been installed in flanges to tighten up all the bolts after sterilization and to check for leaks occasionally. Where possible, the feed should be kept hot (60°C). Reliable valves on feed lines and removable stainless steel strainers with bypass lines at all critical points will improve operations. 

Duplex basket strainer —H )— T type strainer permanent) —— T type strainer temporary) X" —- Vent... 

Compressor suction lines must be free of any foreign panicles that could damage the internals of the machine. Strainers are installed in the inlet line between the block valve and the compressor inlet nozzle. After the unit has been on stream for some time, the strainers are normally removed. Should the strainer be the permanent type, a clean-out connection must be added to remove any trapped foreign matter during a shutdown of the compressor. Exhibit 4-48 illustrates two such applications. 

After 1 h, return the adult zebrafish back to permanent storage tanks, remove the inner container and collect the eggs by straining the water in each breeding tank through a plastic tea strainer. 

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