Suction line strainers

To lessen the risk of pumping sludges or slurries into a unit, the practice is to leave a safety margin of 50 cm (heel) below the outlet nozzle or install a strainer on the pump suction line. The deposits accumulate with time and the tanks are periodically emptied and cleaned. 

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... 

Suction lines are often partly filled by settled sand and by debris from the pits, causing the pump to hammer at abnormally low speeds. Frequent inspection and cleaning of the suction manifold is required. The suction strainer can also be a liability if it is not cleaned frequently. 

Strainers are used primarily to catch only very large particles and will be found in applications where this type of protection is required. Most hydraulic systems have a strainer in the reservoir at the inlet to the suction line of the pump. A strainer is used in lieu of a filter to reduce its chance of being clogged and starving the pump. However, since this strainer is located in the reservoir, its... 

The suction line from solution feed pump can now be inserted into the pipe leading to the inner cone or manifold as the case may be. The foot valve and strainer on the suction line should be 2-3 in. above the bottom of the saturator tank. Make sure the feed pump has an anti-siphon valve, which will prevent overdosing. The saturator can now be placed into service. 

At this stage, sensitive instruments and control valves may be absent from the system, in order to prevent damage from any debris flushed through pipework, and replaced by temporary spool pieces. Strainers should be fitted to the suction lines of pumps and certain compressors. Orifice plates should be omitted. 

Whether liquid contains suspended particles or it is clean (strainer will be required in suction line for proper functioning of the pump)... 

Strainer in suction line clogged. Clean strainer. If problem persists, determine the source of debris in strainer and eliminate it or install a strainer with larger mesh (or install pump that can tolerate the solids load. 

Strainer in suction line partially clogged. Same solutions as for no flow symptom described on page 123. 

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. 

Exhibit 8-22 iliu-strates how a common standby pump is used for two primary pumps this is the ideal layout, with flexibility loops added as reciuired. Exhibit 8-23 shows how the suction line for service B is tied into the suction line for. service A below or down-strearn from the block valve and up.stream from the strainer. The discharge line for service B is tied in downstream from the check valve. 

Such inlet strainers, of course, do not remove any pump-generated contantina-tion, which is then fed directly into the system on the pressure side. Equally, they are not necessary in systems with closed reservoirs, with silt-control filtration on the return line, or where fluid is introduced into the system upstream of the return line filter. Suction line filters are cheap, but do not usually have indicators to show when they are dirty or blocked. 

The water in the pump suction well is chlorinated to control biofouling by the injection of sodium hypochlorite from a 10,000 gallon tank. Four vertical diffusers in each pump suction well distribute the sodium hypochlorite. RSIP item B151 (Reference 74) includes provision for adding strainer pressure instrumentation in the cooling water booster pump building, strainer bypass lines, and other improvements that will allow better operator monitoring, controls, and shutdown of pumps if the pressure limits are exceeded. 

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