Thank you sir for your reply.
I am confused because of the below mentioned answer
What is a close coupled pump?
A type of pump that involves an impeller as the central element of the motor component. The pump doesn’t have a separate coupling, and thus eliminate coupling alignment, one of the more expensive and time-consuming operations of pumps that aren’t close-coupled.
How do they work? In a close coupled pump, the impeller is on the same shaft as the electric motor that drives the pump. The motor has a machined face on one end, which matches the face on the pump casing that is mounted against the motor face. The bearings that are in the motor must handle the forces generated by the pump, since it doesn’t have its own separate bearing housing.
What applications are they used?
The simplicity, versatility, and relatively low cost of this type of pump make them useful in many industries. They typically are used with relatively simple seals, so they are limited as to temperature and to relatively non corrosive liquids. Because the bearings are located in the motor, close couple pumps are limited in size to about 40-50 hp for most applications.
Other related Pump Types include: industrial pumps, horizontal split case pumps, process pump, chemical process pump.[/b]
I do not have any argument or comment about your write-up on "What is a close coupled pump?"
Pumps can be categorized many ways including; Type (or Mechanical Design Configuration); Industry Application; Function; etc such as:
- industrial pumps - This is an "Application"
- horizontal split case pumps - "This is a Mechanical Design Configuration"
- process pump - This is an "Application"
- chemical process pump - This is an "Application"
- Booster Pump - This is a "Pump Function"
- Recycle Pump - This is a "Pump Function"
- Charge Pump - This is a "Pump Function"
- Single Stage Pump - "This is a Mechanical Design Configuration"
- Vertical Sump Pump - "This is a Mechanical Design Configuration"
- Inline Pump - "This is a Mechanical Design Configuration"
- Close Coupled Pump - "This is a Mechanical Design Configuration"
- Mono-block Pump - "This is a Mechanical Design Configuration"
- Can Pump - "This is a Mechanical Design Configuration"
- Waste Water Pump - "Industry Application"
It is a deep subject.
Sometimes its possible to do all the right things and still get bad results
Try Google and look at the various configurations, it is class 101 for pump engineers.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
In my usage a close coupled is common shaft, no coupling, pump bolted straight to the motor.
Mono-block has the pump housing and motor housing as the same piece of metal, the pump cannot be removed.
Close coupled advantages - space saving, eliminated baseplate/coupling alignment issues, cheaper to purchase
Close coupled disadvantages - have to remove pump and motor to perform maintenance, often have assembly/disassembly problems due to corrosion, some designs put hydraulic loads onto motor bearings (not always designed for this), most motors offer excessive axial movement causing seal compression issues.
From our experience we typically see close coupled (no coupling) in applications with throw away components. Essentially by the time the pump or motor wears out you just replace the whole shot.
The little known secret in the industry, is that having a spacer coupling in between your pump and motor greatly increases the overall life of each. Plus it allows you to get full life out of both. It really comes back to upfront cost, cost of downtime, and cost of replacement.
When it comes to couplings we are always here to help.
The close coupled pump is generally the cheaper way to manufacture a pump and an ideal solution fro lots of applications, however (always a however...) because it is a common shaft between pump and motor you rely on the motor bearings to accept the hydraulic thrust caused, especially, by end of curve operation and with a closed impeller the axial thrust can very quickly become very high. Due to the drive for lower prices, engineering is constantly being 'trimmed' and lots of motors now don't accept anywhere near the axial loads they once did, so motor life is reduced.
Our mono-block design of pump also includes an additional bearing for withstanding axial loads so not replying on the motor which of course results in a much longer operational life.
Our final option is a traditional end suction pump with both radial and axial thrust bearings, and we add a flange for close coupling a motor with traditional coupling but with the robustness of a long coupled DIN24256 pump, but with a degree of compactness, but certainly removing the need for laser alignment etc...
So, generally, buy cheap, buy twice, but hope this gives a bit of an insight into the options for you...
Most motor are provided as standard with a ball race at either end which can handle a small amount of axial load. It is possible to specify the motor with, for example, a roller bearing at the drive end to handle heavy radial loads from belt drive applications, or an angular contact ball type to handle the axial thrust from direct-drive fans and close-coupled pumps.
None of the above is news to pump manufacturers who will take the cheapest option meeting the specification, which likely involves running the pump somewhere near its curve. Abusing the pump and killing the bearings with excessive axial load won't find much sympathy from the manufacturer.
On motor overhauls - beware of the bottom-feeder motor overhaul shops who typically fit whatever bearing is cheapest on the assumption that you won't check. It is very embarassing for them when client-from-hell demands a newly-overhauled motor is opened up for a spot check and their cheap job is exposed. They only do it once.
