You will get a lot of advice saying that there should be nothing but straight pipe for 20 pipe diameters upstream of the pump. This is theory.
Most "Cone" type temporary strainers are installed within the first 5 feet (1.5 meters) upstream of a pump. That's a fact and the pump works just fine. This is practical application.
We are left with the war between theory and practical application.
You still have to consider the whole problem.
The function of the line and the pump
The operation of the line and the pump
The maintenance of the line and the pump
The material and fabrication of the line
Generally nothing but straight pipe in less than 5 diameters is recommended and 5 D is no guarantee you won't have issues. How much less than 5 D depends on pipe configuration, type of pump and operating conditions and how much maintenance expense you're willing to pay for in the future.
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"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
If the strainer truly is temporary, any issues should go away when you remove it. What size piping are you talking about? Is putting a temporary strainer within 5 feet of the pump going to be less than 5 times the diameter?
Patricia Lougheed
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.
we have quite a few line sizes for the temp strainers. Yes, they are for startup only and will be removed. One of the removable spools holding the cone strainer is an 8" line and the cone is only about a foot from the suction nozzle. This seems too close, hence the reason for my post.
We do not have any requirement for a temporary suction strainer that requires it to be back a certain distance from the suction. The key to this is that it is truly temporary. We require that this strainer be removed after a minimum of 4 hours and a maximum of 24 hours of operation. It is just there to catch weld slag and tape measurers left behind by careless pipe fitters. We often install the temporary strainer right up against the pump suction flange and have had no problems over several hundred installations.
Not such a good time limit for pipelines which may take days or weeks (or even longer) to sweep a line, if it ever gets swept before other things start finding their way in there.
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"Pumping accounts for 20% of the world’s energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies)
Maybe we need to ask what industry Pipe15 is in and how long his pipe runs are; it may make a difference how close the strainer can go if he's only leaving it in for <24 hours versus a couple weeks.
Patricia Lougheed
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.
I may be wrong, but the cone strainer is not like elbows or tees that induce swirl into the flow and cause uneven forces when clean. It does take some pressure drop but it is concentric so it straightens flow into the pump. The downside is that even a clean cone generates pressure drop which may lead to insufficient NPSHa, especially if it has small holes, too short a cone or catches too much trash. Whether you have sufficient suction head is the key. The cone When dirty pumping problems may occur, but it has to be better than a catastrophic failure from a bolt.
