3 ms·

> so frequently that the building had to replace pump motors every two years How long should a pump motor last? Anyone know?

verelo 5y ago
If it’s anything like a regular house sump pump (which i suspect it’s not, they should be way higher duty in a building like this), I’ve seen the pumps last 10-20 years without too many issues.
- koolba 5y ago
  That depends on how often they cycle on/off. In brutal conditions of constant use, I’ve seen them fail after 3-4 years.
  - MattGaiser 5y ago
    But that would point to this being a case of brutal conditions with constant use. My real question was to try and grasp how much water they were pumping compared to others.
  - cratermoon 5y ago
    Yes, which is exactly the problem here. Those pumps should not have been in constant use. The fact that they failed so often means they were being run far more than would be expected under normal conditions.
    - deleted 5y ago
      [deleted]
    - verelo 5y ago
      Yeah, i imagine in cases where this is to be expected, the sumps themselves need to be much larger (or have more of them) and the pumps need to be higher duty and intended to move more water. Certainly exceptional, but i'd hope anticipated in the design. Our sump here runs all the time when it rains, but then it goes for weeks without moving any water (especially in the winter). When we moved into this house, the pump was broken, but there was also water damage in the basement. First thing i did was replace it and now its a common sound to hear the pump running.
- deleted 5y ago
  [deleted]
  - deleted 5y ago
    [deleted]
- na85 5y ago
  I lived in a place in Ontario where the grading wasn't correct and my sump pumps were failing every 18-24 months. It would run for days after a heavy rain.
sigstoat 5y ago
contra the sibling comment, i've seen lots of home depot house sump pumps that just last a couple of years. quality, conditions, actual duty cycle vs designed, etc.
beerandt 5y ago
Miami is making the same mistake New Orleans made 100 years ago. They're trying to artificially lower their water table to improve drainage, but it creates a cycle of subsidence, which makes flooding worse, which makes them pump more, repeat. They luckily don't have large organic deposits (that I'm aware of), so total subsidence will be much less than New Orleans, but same concept. Back to your question, the pumps were probably designed or spec'd for a capacity that they are having to exceed in increasing amounts.
- freewilly1040 5y ago
  Are there really other options besides evacuating the city?
  - mikewarot 5y ago
    Instead of trying to lower the water level, Chicago raised "ground level" https://en.wikipedia.org/wiki/Raising_of_Chicago https://en.wikipedia.org/wiki/Raising_of_Chicago
    - freewilly1040 5y ago
      Interesting, thank you for the link!
- elihu 5y ago
  That also sounds like it would pull in salt water, which as I understand it is a problem at least in Jakarta: a lot of previously fresh-water wells in the area have become salty due to ocean water seeping in to fill the void.
  - beerandt 5y ago
    That's for deep water drinking wells. Baton Rouge and south Louisiana are going through that now, with salt water penetrating a fault line that was once considered a barrier. The industrial corridor along the Mississippi consume an unbelievable amount of fresh water, so the same lesson might not apply to most areas. Pumping drainage and the ground water table is probably drawing salt water, but at shallow depths. Not deep enough for actual water wells.
kube-system 5y ago
Depends on the pump and the application. If anything, that statement says more about the choice of pump than the issue it was trying to solve.
jaclaz 5y ago
>How long should a pump motor last? Anyone know? Obviously it depends a lot on the specific type of pump, motors are - generally speaking - very long lasting, I would say (proper type of pump, properly dimensioned, used according to specs, and maintained/repaired) anything between 10 and 20 years. The more common issues are outbound leaks (from the axle gasket) in external pumps and inbound leaks (from the outer case or gaskets) in submersible pumps, and of course from time to time you need to change the bearings. In the case of submersible pumps, leaks usually mean also a motor failure (again it depends on the type of pumps) expecially on rarely used pumps as bearings will clog and the motor will then likely need too power, and overheat. On the other hand, external pumps (air cooled) often overheat because of the poorer cooling, if subjected to lots of "start and stop", electrical motors, particularly if large, tend to create a huge drain of power (often 3x to 5x) when starting (as compared to normally running) and this inrush of current translates in a huge amount of heat (and more generally stress to the motor), so many starts in a limited time are not good for the life of the motor, lately things were mitigated by electronic starters that allow for smoother (less peak Amps) starting. The electrical setup/controls may also play a role, a good, well calculated pumping station (such as those used to evacuate leaks in an underground construction) is generally 100% redundant (i.e. two pumps when only one is needed, in some cases 300%), and have automations that alternate the use of pumps (so that each motor and bearings actually run when pumping is required) and use "the other pump" if there are too many motor starts in a given hour, plus there can be a sort of valve that allows to pump the water within the reservoir, so that even if there is no need to pump water "out" pumps are "exercized" periodically, this latter is also often used to avoid too many starts, once a pump is started, it runs for a given number of minutes minimum, part of which is actually used to pump water outside - i.e. responding to the event that triggered the start - and the rest it runs "idle" pumping water within the reservoir through the by-pass valve, so that if a new event re-triggers the start, the pump is already running and only the valve is closed to make it pump water out. But otherwise what you routinely (I would say every two-three years for external pumps and maybe 5 years for submersible ones) do is check gaskets and bearings and replace them if needed.

verelo 5y ago

If it’s anything like a regular house sump pump (which i suspect it’s not, they should be way higher duty in a building like this), I’ve seen the pumps last 10-20 years without too many issues.

koolba 5y ago
That depends on how often they cycle on/off. In brutal conditions of constant use, I’ve seen them fail after 3-4 years.
- MattGaiser 5y ago
  But that would point to this being a case of brutal conditions with constant use. My real question was to try and grasp how much water they were pumping compared to others.
- cratermoon 5y ago
  Yes, which is exactly the problem here. Those pumps should not have been in constant use. The fact that they failed so often means they were being run far more than would be expected under normal conditions.
  - deleted 5y ago
    [deleted]
  - verelo 5y ago
    Yeah, i imagine in cases where this is to be expected, the sumps themselves need to be much larger (or have more of them) and the pumps need to be higher duty and intended to move more water. Certainly exceptional, but i'd hope anticipated in the design. Our sump here runs all the time when it rains, but then it goes for weeks without moving any water (especially in the winter). When we moved into this house, the pump was broken, but there was also water damage in the basement. First thing i did was replace it and now its a common sound to hear the pump running.
deleted 5y ago
[deleted]
- deleted 5y ago
  [deleted]
na85 5y ago
I lived in a place in Ontario where the grading wasn't correct and my sump pumps were failing every 18-24 months. It would run for days after a heavy rain.

sigstoat 5y ago

contra the sibling comment, i've seen lots of home depot house sump pumps that just last a couple of years. quality, conditions, actual duty cycle vs designed, etc.

beerandt 5y ago

Miami is making the same mistake New Orleans made 100 years ago. They're trying to artificially lower their water table to improve drainage, but it creates a cycle of subsidence, which makes flooding worse, which makes them pump more, repeat. They luckily don't have large organic deposits (that I'm aware of), so total subsidence will be much less than New Orleans, but same concept. Back to your question, the pumps were probably designed or spec'd for a capacity that they are having to exceed in increasing amounts.

freewilly1040 5y ago
Are there really other options besides evacuating the city?
- mikewarot 5y ago
  Instead of trying to lower the water level, Chicago raised "ground level" https://en.wikipedia.org/wiki/Raising_of_Chicago https://en.wikipedia.org/wiki/Raising_of_Chicago
  - freewilly1040 5y ago
    Interesting, thank you for the link!
elihu 5y ago
That also sounds like it would pull in salt water, which as I understand it is a problem at least in Jakarta: a lot of previously fresh-water wells in the area have become salty due to ocean water seeping in to fill the void.
- beerandt 5y ago
  That's for deep water drinking wells. Baton Rouge and south Louisiana are going through that now, with salt water penetrating a fault line that was once considered a barrier. The industrial corridor along the Mississippi consume an unbelievable amount of fresh water, so the same lesson might not apply to most areas. Pumping drainage and the ground water table is probably drawing salt water, but at shallow depths. Not deep enough for actual water wells.

kube-system 5y ago

Depends on the pump and the application. If anything, that statement says more about the choice of pump than the issue it was trying to solve.

jaclaz 5y ago

>How long should a pump motor last? Anyone know? Obviously it depends a lot on the specific type of pump, motors are - generally speaking - very long lasting, I would say (proper type of pump, properly dimensioned, used according to specs, and maintained/repaired) anything between 10 and 20 years. The more common issues are outbound leaks (from the axle gasket) in external pumps and inbound leaks (from the outer case or gaskets) in submersible pumps, and of course from time to time you need to change the bearings. In the case of submersible pumps, leaks usually mean also a motor failure (again it depends on the type of pumps) expecially on rarely used pumps as bearings will clog and the motor will then likely need too power, and overheat. On the other hand, external pumps (air cooled) often overheat because of the poorer cooling, if subjected to lots of "start and stop", electrical motors, particularly if large, tend to create a huge drain of power (often 3x to 5x) when starting (as compared to normally running) and this inrush of current translates in a huge amount of heat (and more generally stress to the motor), so many starts in a limited time are not good for the life of the motor, lately things were mitigated by electronic starters that allow for smoother (less peak Amps) starting. The electrical setup/controls may also play a role, a good, well calculated pumping station (such as those used to evacuate leaks in an underground construction) is generally 100% redundant (i.e. two pumps when only one is needed, in some cases 300%), and have automations that alternate the use of pumps (so that each motor and bearings actually run when pumping is required) and use "the other pump" if there are too many motor starts in a given hour, plus there can be a sort of valve that allows to pump the water within the reservoir, so that even if there is no need to pump water "out" pumps are "exercized" periodically, this latter is also often used to avoid too many starts, once a pump is started, it runs for a given number of minutes minimum, part of which is actually used to pump water outside - i.e. responding to the event that triggered the start - and the rest it runs "idle" pumping water within the reservoir through the by-pass valve, so that if a new event re-triggers the start, the pump is already running and only the valve is closed to make it pump water out. But otherwise what you routinely (I would say every two-three years for external pumps and maybe 5 years for submersible ones) do is check gaskets and bearings and replace them if needed.