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N+1 Meaning 1
- Thread starter Dymalica
- Start date
a)N+0, where N equals 6 pumps.
b)N+N
c)N+1
For the pumps. System redundancy depends a great deal on how the components are interconnected.
Rafiq Bulsara
b)N+N
c)N+1
For the pumps. System redundancy depends a great deal on how the components are interconnected.
Rafiq Bulsara
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1
- #4
KiwiMace
Mechanical
- Feb 2, 2006
- 1,012
Assuming that all the pumps are equal capacity, parallel piped on a common header and individually able to be run in place of any other pump...
1. N+1
2. 2N (more common than N+N)
3. N+1
N refers to the number of pumps (or equipment in general) required to meet the design flow (load etc).
N+1 indicates this many pumps and one spare. It could be one pump or a hundred, with one spare. Obviously with 100 duty pumps you might want a few more spares, with N+2, 3, 4 etc. resulting.
2N is a much more substantial deal and refers to a spare for every pump, but is often realized with separate parallel plant so that pipework and accessories and even major plant are replicated. Two pumps, one duty and one spare are usually termed N+1 for this reason.
You can also group redundant equipment - with say one spare for each of four groups of equipment (makes sense in a fan or crac unit context) being 4(N+1).
1. N+1
2. 2N (more common than N+N)
3. N+1
N refers to the number of pumps (or equipment in general) required to meet the design flow (load etc).
N+1 indicates this many pumps and one spare. It could be one pump or a hundred, with one spare. Obviously with 100 duty pumps you might want a few more spares, with N+2, 3, 4 etc. resulting.
2N is a much more substantial deal and refers to a spare for every pump, but is often realized with separate parallel plant so that pipework and accessories and even major plant are replicated. Two pumps, one duty and one spare are usually termed N+1 for this reason.
You can also group redundant equipment - with say one spare for each of four groups of equipment (makes sense in a fan or crac unit context) being 4(N+1).
msquared48
Structural
And I assume that any spares are plumbed into the system, and remain inactive until a valve is opened and another closed?
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
KiwiMace has summed it up.
Mike:
Typical (and recommended) design would be to keep the backup units also running. If more than 1 backups (for n+3 or N+4) etc, one can have a system that will "cycle" the units such that at least one or more backups are operating all the time. You do not want to find out that the back up units did not come on line because of a failure of some other component like a valve or the unit itself.
Again the devil is in the details, of functions and design objectives.
Rafiq Bulsara
Mike:
Typical (and recommended) design would be to keep the backup units also running. If more than 1 backups (for n+3 or N+4) etc, one can have a system that will "cycle" the units such that at least one or more backups are operating all the time. You do not want to find out that the back up units did not come on line because of a failure of some other component like a valve or the unit itself.
Again the devil is in the details, of functions and design objectives.
Rafiq Bulsara
I might add to Rafiq's:
power your pumps, chillers, cooling towers, boilers, etc, each from a separate electrical panel.
So if something goes wrong with the panel, you don't lose your entire plant because a fault in your eletrical panel will render your multiple N to nothing.
Data center design practice.
power your pumps, chillers, cooling towers, boilers, etc, each from a separate electrical panel.
So if something goes wrong with the panel, you don't lose your entire plant because a fault in your eletrical panel will render your multiple N to nothing.
Data center design practice.
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