I believe (and I stand to be corrected) that it is the same impeller/casing as what they call the MegaCPK, so the attached are the 50Hz and 60Hz curves. However, do your due diligence to confirm, or just use this as rough guideline, as it's unlikely that the performance would be radically...
There is a thread ON HERE about this topic:
https://www.eng-tips.com/threads/nfpa-20-dedication-of-fire-pumps.422637/
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Note: I found this paragraph from NFPA 20 - 2016 Edition, but no restrictions!!!
4.7 Pumps, Drivers, and Controllers.
4.7.1* Fire pumps shall be dedicated to and listed for...
As Dynamics Eng has pointed out, API610 is your guide.
Since you refer to it as a BB3 pump, that implies API610 is your reference, so I suggest you read it, as it tells you exactly what to do.
Also, please specify if any codes apply. Does it need to be UL/FM approved? I've dealt with fire pumps that did need FM/UL, but also many that did not. That should be the first thing you specify.
Somewhere in my library of books, I believe I have an old Canadian Code for Wood Framed Structures; if you can search up a copy, it will answer all of your questions, and many that you did not know to ask.
The fact that B is the furthest from the deaerator is very suspicious. Remember that the only NPSH you will have is the elevation from the pump centerline to the level in the deaerator, it is very suspicious that B is being starved, as it is furthest from the DA.
I have never heard of an API stamp for a pump. Manufacturers will build pumps to API standards as noted in their literature. Can you explain more clearly? Are you a customer or potential manufacturer?
If it's always the pump in B position, and you replaced it with a new unit and the same thing occurred, it's an indication that it may not be the pump, it's a piping or operating issue. Verify operation of all valves, check valves, etc.
A google search brings up this being sold by an SKF dealer:
51134 M/DH
51134 M/DH 51134M/DH THRUST BALL BEARING ; DUAL HOUSING WASHER
Thrust Ball Bearing; 170MM Bore 1; 172MM Bore 2; 215MM Outer Diameter; 34MM Height; Single Direction; Not Banded; Brass Cage; ABEC 1 | ISO P0 Precision
The primary differences are the company that manufactures them.
In my experience, Finish Thompson makes some smaller sizes (below ANSI) that others don't.
Having sold these for years, and had to sort out some of the problems, also note that if the truck unloads from the top, and you are using a self priming pump, put it up above the tank level. DO NOT have the pipe come up out of the tank and down to the pump. That does not work.
Frankly...
Interesting story from the CBC the other day; it seems that an engineer has designed quite a number of ~4 story apartment buildings (they are going up here like mad), and didn't properly design/detail the slab over the basement garage, which was discovered by a structural engineer brought in to...
"To plot the composite pump curve, is it okay to assume that Flow_both = (Flow1 + Flow2)/2 "
Think about the question. The pumps are in SERIES. So, if 100 m^3/h comes out of the first pump, where does it go? It has to go to the second pump. The second pump does not manufacture liquid, so it...
It's a safe starting assumption that two pumps will be the same efficiency, but it will be affected by the pump condition / wear, etc, and also the motors. It really depends on what you are looking for, but as others have said, you really need to start with the pump curve, it will have the...
The BVs are necessary if maintenance is ever needed on the pumps, so no matter what else is in the system, the BV should be there. And it is a poor practice to use an isolation valve to balance the line.
I wouldn't use a centrifugal for that. Desmi, for one example, have a chocolate-specific gear pump; I'd look at something along that line, or a PC pump.
In so many cases, the vendor is given the kW rating of the pump, and if lucky, the discharge pipe size, and nobody in the field can give any better data. That's why things like this happen.
I would ask the vendor to look at the 1x2-11. I think it would be a good fit, and for sump pumps like this, 4 pole speeds are generally better.
I don't think I have access to the PSS Goulds sizing program any more, or I would do some curves.
