What essential mechanical criteria must be considered when floor standing centrifugal pump installs?

Roohollah

Dear Professionals ,

We are always considering the installation of floor standing Centrifugal pumps ,and paying close attention to its connections laws . However, there are many examples that this type of pump has been installed without complying the installation with codes . For instance, suction pipe must be 10 times of the inside diameter of the pump's suction straight or the reducer on the suction side of the pump must be eccentric .

I have seen a project which its boiler room comprises of many Centrifugal pumps for heating and swimming pool and jacuzzi's filtration .I decided to request you all for guiding me how to install this type of pump properly and in a way that complies with codes ?


Thank you for being patient with me for such a long message ,



I look forward to hearing from you ,



Yours Sincerely,

Roohollah

Henry

We use a standard of 5 x the diameter of the pipe before and after a pump. The sonly exception is when suction guides are specified.

Roohollah

Dear Henry ,

Thank you for your prompt comment . 5* the diameter of the pipe before and after a pump . It is a practical point for me to put it into practice. What about the brass Y strainer which is the same size of the suction .Shall it be right to consider the mesh of the strainer not to decrease the amount of fluid where Cavitation phenomenon may occur ?

Once more, I do appreciate your comments ,


Sincerely,

Roohollah ,

hot_rod

The manufacturer should supply you with pressure drop charts for the strainer. The size of the mesh needs to be factored in.

http://products.coltonind.com/Asset/108_STR990-1_Pressure-Drop-Data-Y.pdf

The biggest drawback with Y strainers, as they plug they greatly reduce flow, they must be maintained on dirty or old systems, see graphic.

This Chicago area manufacturer has introduced a new concept with less pressure drop and more mesh area.

http://www.metraflex.com/strainers-and-suction-diffusers/lpd-y-strainer/


Another option is a dirt separator or vortex type.

Jamie Hall

There are really only two critical points to consider with centrifugals (other than codes...), and they form a starting point to thinking about how to install them, particularly on the intake side. The first is that the flow should be reasonably straight. Otherwise one can have unbalanced pressure on the impellor, which may cause vibration. That is the reason for the five times or ten times the diameter straight pipe on the suction side. The other is actually more important: what is called the "net positive suction head" -- or, more simply, the absolute pressure at the inlet. All centrifugals have a minimum absolute pressure -- it will be in the manufacturer's literature -- and one must be sure that one has a safe margin above that pressure. The reason for this is that below that pressure, cavitation will occur in the pump, which causes noise as the least problem -- and which can destroy a pump in a matter of minutes if it is really bad. If you must put a strainer on the intake side of the pump, I would also like to see a pressure gauge after the strainer, before the pump, so that it is possible to see what is happening in there.

hot_rod

Some strainers, like the MetraFlex above have pressure ports across the strainer. This will tell you when the strainer is getting plugged and needs service. Plugged strainers will induce cavitation as Jamie mentioned, and with enough pressure can collapse the strainer basket.

On old systems retro-fits it may be wise to use a smaller mesh at start up, remove it after a few days of flow, or go to a coarser mesh.

Any device that can limit flow to the suction side of a pump can cause problems. In some cases it cannot be avoided like strainers and mixing devices. The main failure is often caused lack of maintenance on the strainer device.

Roohollah

Dear Professionals ,

I profusely thank you all for the clear and informative comments . I took a note the lessons to put them into practice for respecting the pumps vital criteria .Unfortunately, I have seen many installation of this type of the pump without deeper understanding of Pumps affairs connections in my area .
In other words , they think maintenance is just wasting money and putting emphasis on the drawbacks of disregarding pump's service will interpret in making mountain out of molehill .The new attached photographs will prove what i always strive to persuade home owners just to have a better attitude towards hydronic heating or swimming pool industries .


I completely agree with you professionals that MTBF ,temp ,npsha and fluid are the backbones of selecting proper pump for a heating system .Thanks Gil Carson for invention of p&S pumping which has made a revolution in Hydronic heating system . Wishing him rest in eternal peace .

I do appreciate for the comments and the link which provide me with perfect insight into pump industry .


Yours Sincerely ,

Roohollah

hot_rod

Lack of proper installation, startup, and maintenance of pumps and circulators is a world wide epidemic. You are not alone in noticing that mindset

Mark Eatherton

hot rod said:

Lack of proper installation, startup, and maintenance of pumps and circulators is a world wide epidemic. You are not alone in noticing that mindset

And it's not just pumps. It's pretty much every component in a hydronic system, which inadvertently proves a good point. You can have a WHOLE bunch of stuff screwed up, in the wrong place, in the wrong position, and these system STLL produce a great feeling of comfort than any other system on the market...

And just to clarify, I don't believe it is actually "code" per se, other than the code deferring to the manufacturers installation instructions. I think it falls more under the category of "best practices", which is common sense at its finest. Unfortunately, common sense is not so common any more.

As it pertains to strainers, I understand the engineers reasoning behind putting them before the pump, wanting to protect the pump from "chunks" floating through the system, but seriously, if you in fact have anything "chunking up" in your system, you have a WHOLE bunch of other problems that need to be addressed.

Start clean (per the code) and keep it clean, and it lessens the need for any sort of strainer. The one rule that can't and shouldn't be violated is the pumps position as it relates the expansion tank connection. All pumps MUST pump away from the PONPC in order for the pump to produce all positive (+) pressure differential.

Our job of education will NEVER end...

ME

Roohollah

Dear Friends,

Thank you for the comments and analyzing the failures in deeper layers . there is no end in education and experiencing new situations in this industry .It is like an ocean and we are limited to dive into deeper depth of the ocean .

I warmly do appreciate for lighting the true path for me not to be lost in the technical turmoil of the industry .


With regard to the above comment , i would like to mention that I have seen many projects where there were many apparatuses in boiler rooms or water treatment plants for aquatic facilities which had not been maintained since their first start up . Therefor, I agree with Mr.Eatherton that when system is entirely under control and maintenance has been considered completely ,why using the equipment which never controls by many operators. For instance, Those in line basket strainers , if some one wants to clean inside of them and remove dirt , he may not able to seal it again .So, the fear of such a scenario , will overturn the idea of keeping every thing to be cleaned .


As for me , we always do it even if it causes many problems or takes much more time .To be honest , I have seen much dirt in them unless the systems have been installed by other crew and the owners pay less attention to their maintenance and operation .The last attached photographs are great examples of non professional installation of floor standing centrifugal pump ( 7.5 HP ) for jacuzzi massage jets .


Another complexity of considering the idea of the more complex , the better the system , Please have a look at these new photographs .


I look forward to hearing from you ,


Thank you for your patience and time ,


Yours Sincerely,

Roohollah ,

SWEI

Wow. That is some beautiful pipe work!

Roohollah

SWEI said:

Wow. That is some beautiful pipe work!

Dear Friend ,

Thank you for the comment . It seems beautiful on the surface . But , it is not . Installers have piped heating lines of the boilers to the tube of Jacuzzi and pool heat exchangers , and clean and clarified pool's water supplies over tube of heat exchangers which is in contact with black shells and it turns the clean water dirty whenever the pool or jacuzzi pumps stop for hours . also, the location of Unions in the piping are situated before gate valves ,and the source of water is in opposite side of Unions and many other errors .


once more , thank you for your attention and time ,


Sincerely,

Roohollah