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the correct answer is 26.3 ft(please find the attached ). but when calculate i am getting 69 ft. atmos head in ft= 14.7x2.31/0.8= 42.44 head at top of liq in ft= 10x2.31/0.8= 28.87 head loss due to friction in feet = 2 varpour pressure in feet = 5.4x2.31/.8= 15.59 static head in feet= 15 npsha=...

what is the NPSHA?

Rotodynamic pump , operating in closed system with following conditions: liquid level above pump centreline is 15 ft; suction vessel pressure at top of liq. level is 10 psi; suction friction loss is 2 ft; liq vapor pressure is 5.4 psia;atmospheric pressure is 14.7 psia; liq specific gravity is...

What is vane overlap? What is the cause? How can we avoid the same?

Some people in UAE uses fire system for other uses like watering plants or cleaning their sheds etc. So that might be reason for them to go for two diff pump set. I cant see any other reason as to why . both UL pumps means really high price.should ask client itself. Anyway the drawings whould be...

Dear Littleinch/rotw, Thank you for your help. Yes it did help alot. I think its clear now. Now my pump department is just about to start in few months so may b piratical experience while doing the test and trimming will give me idea. As you said this model for 1500 is a not very efficient...

a lesser micron filter in the suction side and cleaning the same in regular basis can solve the problem i think.

In ships it mostly mechanical seals in all pumps. I myself in a marine engineer. I have not come across gland packing if i can remember right

sorry for the earlier post i have attched the data with this one. So is there any way one can identify the pumps rated flow and bar with just testing if he as no clue about the same? lets say no name plate is there in the pump to show its rated point and i want to test and sell it with its...

These are the datas i got for minimum impeller. Impeller Size: Minimum Condition: Head Suction Pressure Delivery Pressure Flow RPM Power 3.5 bar 12.2 bar 0 M^3/hr 1497 RPM 60.14 kW 2 bar 10.8 bar 91.2 M^3/hr 1496 RPM 74.76 kW 2 bar 10.8 bar 136.87 M^3/hr 1497 RPM...

Dear Rotw, As you said i am using a test set up. I get my models with maximum impeller. I do calculation if find out how much i should trim to bring down the rated flow and head as per customer requirement. Then i do retesting. But how can i ensure from the test result that the trimming i did...

Thank you for your help. I had checked this site before but couldnt find the one required but anyway i finally made one.http://files.engineering.com/getfile.aspx?folder=b6d7a4c7-a9b1-4066-a471-5a2a152b5b88&file=impeller_balancing_report.pdf

Thank you for your answers. To be more precise . For every model there is a max. impeller and a minimum impeller. I am getting the pumps with the max. impeller. Then i trim to get the intermediate points as per customer requirement. Lets say my 1500 gpm model i am trimming to a flowrate of...

After i trim my impeller and test my pump again . how can i know the new rated point?

Dear All, Can anybody help me with providing a sample pdf for dynamic balancing report of impeller. I just want a base to make my own. Thank you in advance.

The power drop is important for a fire fightinig pump . Its an extra safety measure to ensure power wont keep on increasing to motor burns. This case is very rare tht the pump goes to that point. but in fre fighting pumps we do take that extra measure. I have attched a data table showing the...

Thank you for the answers. As you said its all depends upon pump selection. In order to be on the safer side and pass some tests my vendor selected a bit bigger size foreseeing the requirement of power drop. Now that the model is already selected and got the approvals for materials used , I was...

I meant power drop point as the point in the power curve of centrifugal pump where the power starts dropping. It should happen after 150 percent flow. but i want to make it happen close to 150 percent flow. Changing motor wont help as it is dependent on pump design.

What is the design characteristics in a pump that decides the power drop point? During testing of pump after the 150 % flow the power keep on increasing to a point after which either the power drops or stabilizes. How to bring down the point(not below 150 % flow )? can anyone help me out?

Sorry for my late reply ..i was out of station for few days. I realy appriciate for kind heart to help me patiently. Actully the model was tested for rated flow point 100 gpm with maximum and minimum impeller. Out of 8 points taken for plotyin the graph one point was tp gpm. And they gave us...