Q&A Report Short Course 40 (Both Sessions).xlsm

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1	Question Report Short Course 40 First Session
2	Report generated time	4/24/25 2:02
3	Topic	Webinar ID	Actual Start Time	# Question
4	Session No 40 (Eastern): Vertical Pumps (VS1, VS4, VS6).	812 5452 0911	4/24/25 0:50	19
5	Question Details
6	#	Question	Asker Name	Answer
7	1	please elaborate difference between NPSHA and minimum submergence in vertical pump applications	Aamir Hasnain	Minimum submergence takes into account suction vortex formation as well as NPSH Available
8	2	how is oil supplied in oil lubricated VS1 pumps?	Anonymous Attendee	A small reservoir mounted on the discharge head and tubing to the shaft enclosing tube. It only needs a couuple of drops per minute.
9	3	Are bottom bearings (before 1st impeller) in vertical pump applications only good to have or mandatory in your opinion, specially where pump stages are more?	Aamir Hasnain	The Ruhrpumpen designs all have a bearing in the suction bellmouth. Usually it is grease packed. We consider this construction gives the best shaft support. Some pump suppliers do not have such a bearing. This does lead to a larger accessible eye area and so potentially lower NPSHR
10	4	What is the design concept behind, large pump is lubrication oil, smaller pump is greased lubricated?	Osama Elnahrawi	I could have put that better in the presentation - sorry The real issues are length of pump above the water level and cleanliness of the pumpage. A long pump may lead to dry running bearings above the water level for a few seconds during startup. If there is sand or grit in the pumpage then having enclosed lineshaft will protect the bearings
11	5	upto what extent of particle size, the standard bush bearing are suitable for VS1 pumps?	Ninad Pandya
12	6	For vertical pumps, is reverse rotation protection is necessary or can be ignored. Specially high flow pumps where there is lot of liquid present in piping before check valve?	Aamir Hasnain	Pumps can withstand reverse rotation. Nevertheless we always recommend a check valve in the discharge pipework. It is important that the motor not attempt to restart while the pump is backspinning. A time delay circuit
13	7	1. Untuk pompa dengan flow yg besar apakah perlu baffle disisi inlet untuk mengurangi atau menghilangkan turbulen atau swiller 2. beberpa client minta anti rotation pada pump, bisa dijelaskan design dari ruhrpumpen	Abrudin Abrudin
14	8	1. For pumps with large flow, is a baffle needed on the inlet side to reduce or eliminate turbulence or swill? 2. Some clients ask for anti-rotation on the pump, can you explain the design of the ruhrpumpen?	Abrudin Abrudin	A well designed inlet will not need flow straighteners. We have supplied them as part of a specially designed suction strainer in order to correct the inlet flow in a badly designed inlet.
15	9	What is max length possible fr VS1, VS2 pump?	Pushpak Akhade
16	10	What are max stages possible for VS1, VS2 pump?	Pushpak Akhade	Depends on the pump size and design 20 stages is not uncommon for smaller VS1 pumps designed for borehole service. Larger pumps such as sea water lift pumps may have 8 or 9 stages. Large VS2/3 pumps will usually have 1 or 2 stages
17	11	In vertical pumps, the minimum submersible length mentioned, are they for operating flowrate or for the max flow a pump can develop?	TUSHAR MAHALE	You should cover the foreseen operating range. If operation at end of curve is possible (for longer than a few seconds during start-up) then you need to cover this eventuality. Since it is the System Curve that determines where the pump will operate on the Pump Curve, that is what you need to consider. Is there a system curve that crosses the pump curve at end of curve.
18	12	Is NPSH test required in vertical pumps, in adition to the sumergence test?	Maria Luisa Velasco	For large pumps most manufacturers cannot carry out a proper NPSH test (with vacuum suppression or suction throttling. These pumps are normally tested in an open sump configuration. A submergence test is a very real simulation of the real world situation. Run the pump without recirculating the flow so the suction level falls until a fall off in performance is seen
19	13	What is max. tolerance for vibration on diesel engine driven VS1 pump?	Pushpak Akhade	Pump vibration limit would be whatever the pump specification allows If it is to API610 then this value is 3mm/s RMS within the Preferred Operating Region, or 3.9mm/s RMS within the Allowable Operating Regionmeasured at the thrust bearing. The diesel engine is completely separate from the pump from this point of view.
20	14	what is typically the max. shaft section length for a VS3 pump	Mike Woodman	Typically 10ft (3m)
21	15	How movement of VS1 pump bottom is prevented, as it is supported at the top onlt?	Pushpak Akhade	It has seldom been a problem. Even on offshore platforms as sea water lift or fire pumps the pump is installed in a caisson or stilling tube and needs no protection from sea currents or waves. Sometimes wheeled centralisers are provided on this type of pump but this is primarrily to protect the applied linings on the stilling tubes from damage while the pump is being installed or removed.
22	16	with thrust bearing in motor, the coupling b/w pump and motor is rigid, that means all the vibrations is transmitted to motor bearings. my thinking is that thrust bearing should be on pump side with a flexible coupling between pump and motor to avoid vibration transmission. What is your preference?	Aamir Hasnain	Both thrust bearing in pump and thrust bearing in motor designs are well established and proven in the field. It is just an example of how designs developed differently on either side of the Atlantic. One advantage of thrust in motor is that the pump height above the foundation will be less than with a thrust bearing in the pump discharge head. On a large pump this could be as much as 1.5m difference.
23	17	For how much flow you recommend Sump Model Test for Sump design	Aamir Hasnain	A sump model test is recommended if it is a new design of inlet or sump. If it is a well established design then it is probably not necessary
24	18	Is it true that we consider VS1 for applications with inadequate net positive suction head?	stephen wambua	When NPSHA is inadequate you probably need a VS6 pump, which is a variation of a VS1 pump. I will be covering VS6 pumps in detail in part 2 of this Short Course on Vertical Pumps on 22nd May
25	19	upto what extent of particle size the standard bush bearing are suitable for VS1 pumps?	Anonymous Attendee
26	20	Hi, what about vertical pumps used in Liquid Ammonia tanks (-31 C 1 bar), does Ruhrpumpen have also pumps for that application ? ( seems Ebara is the only one…)	Yvan Van Hoof	Very good question. The LNG market regulations went along the route of allowing no tank penetrations in the side of LNG storage tanks. Thus all the pumps had to be VS1 pumps entering from the top of the tank. Very quickly this market became exclusively submerged motor pumps. LPG installations have followed LNG ones but not to the same extent. Side penetrations are still allowed and “conventional” pumps are allowed. Frequently VS6 pumps The ammonia market has not legislated in the same way and side penetrations in tanks is still allowed. Although there is a movement in the marketplace towards top entry only. Ebara (now Elliott) developed their submerged motor technology for ammonia pumps and are seeing an upturn in this market. But, yes they are the only ones who do this. (I worked for Ebara Cryo up until my retirement) Most ammonia installations worldwide are with side tank penetrations and VS6 pumps, and are likely to continue that way. Conventional VS1 lineshaft type pumps can also be used with suitable low temperature materials Low temp steels are limited in availability so A8 construction tends to be the way it goes. A VS6 pump will therefore be a less expensive option than the conventional VS1 or the Ebara/Elliott submerged motor pump
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29	Question Report Short Course 40 Second Session
30	Report generated time	4/24/25 10:52
31	Topic	Webinar ID	Actual Start Time	# Question
32	Session No 40 (Western): Vertical Pumps (VS1, VS4, VS6)	897 3196 9517	4/24/25 9:44	13
33	Question Details
34	#	Question	Asker Name	Answer
35	21	What is meant when we say the pump is efficient in slide 19. Are we only looking at energy consumption vs outlet hydraulic power (flow x pressure)? Or are we also evaluating the dynamic condition while running in less efficient windows e.g. more wear, more stress, cavitation, vibrations, etc...	Shailindra Sewratan	We are talking about the overal efficiency of the pump handling the specified fluid in the specified duty conditions (flow, head, specific gravity, speed) as verified by a factory performance test.
36	22	Please comment about:	Berardo Farfan
37	23	1 suction conditions, 2 performance with silt-fine sand laden water	Berardo Farfan	1 - Every pump needs to have a properly designed sump or inlet, and have sufficient submergence to ensure sufficient NPSHA and operating without vortices.
38	24	can you discuss some of the applications for these large scale vertical pumps. What is the benefit of these type pumps vs a standard configuration with tanks and centrifiguals pumps?	Anonymous Attendee	The large mixed and axial flow pumps (VS1 & 3)are commonly used in water treatment plants, water supply from reservoirs, main feed pumps to desalination pumps. The medium sized (Mixed Flow VS) pumps are commonly used in water treatment, and offshore in sea water lift and firepump services The smaller radial & Francis vane VS1 pumps are often used as borehole pumps and open sump pumps
39	25	which one is better suitable for lifting out waste oils from sumps and transfer though header to a tank?	Shailindra Sewratan	Without having more details (flows, heads) and seeing that you are talking about waste oils I would expect this to be a VS4 type sump pump application. Could also be a small VS1 pump.
40	26	Is it possible to add a flywheel?	Ignacio Garnero	I have not come across this ever.
41	27	Hi Simon and thank you for you presentation. I have a large experience with propeller pumps up to 1 or 2 m3/s but it is difficult to imagine a pump with a flow of 7, 8 or even 10 m3/s, I suppose a great variation in the static lift, how this variation impact in the operation of the pump?	Osvaldo Greco	I don't think it is so much a matter of variation of static lift. It is just that the system demand (Flowrate) is much higher than you have come across before. Ruhrpumpen has among the widest range of vertical pumps of any major suppliers in the world. (Others include Sulzer, ITT Goulds, Flowserve). All these suppliers have supplied pumps of this sort of size for many, many years.
42	28	Hello, next time can you show the BOM of one cross section view?	Uri Parra	I will see if I can find a suitable Sectional Drawing and attach it to these Q&A answers
43	29	Are there specific models you typically see for geothermal bore hole applications?	Anonymous Attendee	These will be deepwell borehole pumps - VS1, radial or Francis Vane impellers, multistage pumps
44	30	Thanks for info. this subject was too advance for me, to attend your earlier courses, what I shall do, or at least to have their slides?	Anonymous Attendee	Go to www.ruhrpumpen.com and follow the link to RP Short Courses in the top menu bar. This will take you to a full listing of all the short courses. You can download the video and the slideshow of all of them.
45	31	Are Fire Pumps available in VS1, VS2 and VS3?	Brian Fox	VS1 & VS3 - regularly. We supply many firepumps using VS1 hydraulics.
46	32	excellent presentation & info Simon. thank you very much	Anonymous Attendee	My pleasure. Thank you for attending.
47	33	have a beer on us ....lol	jeremy khoo	Most certainly will!
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