8 ms·

Water Pump Theory

94 points by brad0 4y ago

Glawen 4y ago
Why there is no unit conversion with a flick of a button yet? It clearly looks that it has been translated from SI unit (e.g 1 bar or 14.7psi pressure at sea level)
ricksunny 4y ago
Well (as opposed to all the HN posts about Rust and GoLang), this is a topic I actually know a smidgen about while running a solar water pump venture out of East Africa. AMA.
- simonebrunozzi 4y ago
  Nobody took advantage of the opportunity! I will now. I am somewhat involved in a restoration project of a building in Italy (pet project, not my job, I'm a tech guy). We are considering installing geothermal power to warm/cool the building. Anything of what you know applies to that? There is a water canal nearby, and therefore there's a plan B that involves exchanging heat with the water in the canal.
  - ricksunny 4y ago
    I wish I could speak to geothermal, but it’s just a different industry & technology (maybe it’s like the the difference between architecting a chat app vs a ride-hailing app..? :) ). Yet +1 for the sustainability approach there, always a fan of those intentions =) Things I know revolve around the content of this video I produced: https://www.youtube.com/watch?v=1ZLkmrAvAzE https://www.youtube.com/watch?v=1ZLkmrAvAzE Relevance to original article, for example, are that there are ventures around here that focus on water suction, but their scope is practically limited to surface water. We’ve focused exclusively on submersible pumps so that farmers with wells can tap their groundwater for agriculture with us.
- na85 4y ago
  What do you use for energy storage for dark hours?
  - ricksunny 4y ago
    We avoid electrical energy storage currently. Couple of reasons: 1. Product has to be simple to be adopted effectively. Batteries or overhead tanks imply additional management overhead on the part of the farmer, and that management has to be instructed. Difficult to do in this market context. 2. Support - we’ve talked with customers of competitors who do feature a battery storage element, and they’ve complained about getting support when the battery was failing after some time. 3. Cost. We try to get customers onto the first rung of the income-generation ladder. Higher-income rungs can be achieved with incremental investment, and energy storage is a good example of this. 4. Agronomy: Water-logging plant roots consistently at night is no bueno: fungus, restricting nighttime gas transfer between the roots and soil. That said, the case for storing energy during dark hours can still be a good one, provided 1-4 are satisfied/mitigated. Early morning hours are an excellent interval to irrigate over, and the solar irradiance at those hours is often still too low to utilize the pump’s full delivery & depth (head) capability.
- brad0 4y ago
  I'm a bit late, but what's the technical setup? I'm curious about the panel, controller and pump. What's the wattage and parts etc. What's the final cost? Finally, what problem are you solving for?
  - ricksunny 4y ago
    >Finally, what problem are you solving for? Smallhold farmer livelihoods that are underachieving relative to their capacity. Solar water pump (SWP) systems are expensive to our target market of smallhold farmers when purchased with up-front cash. Since a SWP is an income-generating appliance for its user (apply water toward grow crops -> sell crops -> $$) we focus on how the farmer can sustainably make a down-payment and pay off the SWP on a rent-to-own basis. The market and industry space is widely distributed, so we target equipping distributors to accomplish the above with farmers in their respective geographies. >what's the technical setup? > the panel Typically 120-200W collapsible solar panels that the farmer deploys daily. > controller Our IoT controller that collects local environmental & usage data that equips distributors to monitor their productivity (and so their anticipated loan performance). > and pump. DC-submersible, capable of delivering shallow groundwater accumulated over recent rainy seasons. (Power level matches the panels minus losses). Difficult to go into more detail than that without exposing more about our specific go-to-market strategy rather than anything that helps bring more farmers and distributors to the table. At the end of the day, pump models & panel sizes run the gamut in any given country's market - we help distributors select among these in their local market rather than exporting one SKU to everybody. >What's the wattage and parts etc. As above, with hosing & cabling sufficient for the groundwater depths involved. Accessories beyond that like sprinklers and a bag for carrying are generally appreciated by farmers. >What's the final cost? We have offerings between $600-$1300 paid out over a year. Of course a distributor can choose whatever payout plan they feel their local farmer market will bear.
madaxe_again 4y ago
All of the priming and vacuum issues they describe is why I swear by submersible pumps. I use a pair of deep well pumps to move water up 70m, each doing a 35m lift, with a relay tank halfway.
monkendrunky 4y ago
having small amount of solid sugar, let it mix with saliva, let it go down on throat, and then drink some water -- this has never ever ever failed me!
superb-owl 4y ago
This was fun to read. Anyone know where I might find the relevant equations/math?
- na85 4y ago
  Any undergraduate intro to fluid mechanics textbook will cover this material thoroughly. Looking at my bookshelf I have "Fluid Mechanics" by Frank M White from third year fluids back in the early 00s which treats this material in a chapter called Turbomachinery, building upon the preceding 10 chapters or so. If you don't want to deal with calculus you can get most of the way there with the Bernoulli equation and friends. Edit: this looks pretty good after a cursory glance: http://brennen.caltech.edu/fluidbook/ http://brennen.caltech.edu/fluidbook/
  - otter-rock 4y ago
    Fundamentals of fluid mechanics by Munson et al is also good.
  - timr 4y ago
    If you only get 26 feet of head, how do they manage to pump water from (say) the water tunnels that are hundreds of feet under Manhattan? Is it just that the pressure in the tunnels is well above 1atm?
    - woodruffw 4y ago
      The pressure in NYC's water tunnels brings the water up to about the 6th storey[1]. Beyond that additional pumps and tanks are needed, which is why NYC's skyline is covered in wooden water tanks (except for the newer buildings, which often have internal metal ones). [1]: https://untappedcities.com/2021/01/22/how-does-water-tower-work/ https://untappedcities.com/2021/01/22/how-does-water-tower-w...
      - timr 4y ago
        That's not what I'm referring to. Yes, the water system is pressurized (as are all), but the tunnels themselves are ~500 feet below ground [1][2]. Water is pumped to valve chambers which are themselves far (~250 feet) below ground, then again to the surface. The head pressure on a 500 foot column of water would be over 200psi. This article [3] says that the first leg of water tunnel three runs at over 300 psi, though, so maybe that's the answer. It just seems crazy. [1] https://en.wikipedia.org/wiki/New_York_City_Water_Tunnel_No._3#:~:text=upstate%20water%20supply.-,Water%20Tunnel%20No.,completed%20until%20at%20least%202026 https://en.wikipedia.org/wiki/New_York_City_Water_Tunnel_No..... [2] https://www.theverge.com/2013/10/19/4853636/underground-with-manhattans-new-water-tunnel-three-photo-essay https://www.theverge.com/2013/10/19/4853636/underground-with... [3] https://www.baltimoresun.com/news/bs-xpm-1998-08-21-1998233084-story.html https://www.baltimoresun.com/news/bs-xpm-1998-08-21-19982330...
elromulous 4y ago
Tangent: seeing the title and the Honda url, I was certain this was going to be related to the engine air pump model[1]. Since engines are limited by the amount of air they can push through, you then think of the engine as an air pump (and try to optimize around that). Although this model is fairly commonly used in the automotive industry, details online are surpassingly sparse. Taylor[2] has a bunch of details on it. [1] https://www.roadandtrack.com/car-culture/news/a29588/how-internal-combustion-engines-work/ https://www.roadandtrack.com/car-culture/news/a29588/how-int... [2] https://direct.mit.edu/books/book/4840/Internal-Combustion-Engine-in-Theory-and https://direct.mit.edu/books/book/4840/Internal-Combustion-E...
- otter-rock 4y ago
  That's a very common occurrence outside of software. I know a guy who is famous within his field for certain important discoveries. Later, he "discovered" something else, only to find out that it had been published decades earlier by people in an adjacent subject field, and that parts of industry had been using it for a long time. Years later, there are still no new resources about it. If you know, you know. If you don't, you don't.
sho 4y ago
> This is similar to sucking on a straw Totally random and off topic, but since it took me 40 years to learn the only 100% effective way to get rid of hiccups, this is it. You need to create an extended period of negative pressure in your oesophagus, to de-activate the vagus nerve, or whatever it's called. The reliable way to do this is to have a bottle of water and a straw. Plug your ears if possible - helps but it's not strictly necessary. Crimp the straw somewhat with your teeth. Now spend 20 or 30 seconds slowly, but with a high pressure, sucking water through that straw and swallowing it. Remember, your goal is negative pressure in the oesophagus for an extended period. It is the only reliable method and for some reason is almost completely unknown. Well, now you know! </tangent>
- doliveira 4y ago
  Drinking a full glass of water very quickly has never failed for me, perhaps it does something similar to your method?
- madaxe_again 4y ago
  Same ultimate solution, but no need for any apparatus - lung packing. I learned this incidentally while I was into freediving as a teen. Just take the deepest breath that you can, and then use your tongue and throat to pack more air into your lungs until you feel fit to burst - it may take 20-30 packs. Hold it for ten seconds, then slowly exhale - if you’ve done it right you’ll feel like a deflating air mattress. Hiccups will be gone. If they aren’t, you didn’t pack enough.
- monkendrunky 4y ago
  having small amount of solid sugar, let it mix with saliva, let it go down on throat, and then drink some water -- this has never ever ever failed me!
- newaccount74 4y ago
  > Crimp the straw somewhat with your teeth Damnit. Can't do that with the glass and metal straws we have now... > It is the only reliable method and for some reason is almost completely unknown. Well, now you know! I'm going to patent a straw with a tiny hole on one end and sell it as an anti-hiccup-device. Do you also know of a way to trigger hiccups so I can test my anti-hiccup-device?
martyvis 4y ago
I'm in the process of researching to replace my swimming pool pump. My current one nominally runs at 2850rpm and has a nominal power consumption of 1650W, but I think I measured it at around 1100W. I imagine the maximum load is when starting and also if it has to "suck" with a large head. My pump is about 0.5m above the pool level. It is a 14 year old pump that is obviously just a single phase (240V 50Hz) AC induction motor. The replacements are permanent magnet DC motor driven, with a variable speed (presumably frequency and voltage) drive can control speed from 600 to 2850rpm. After priming at full speed for a few minutes (to purge air) it looks like you can then run it at say 1300 to 1800 rpm and save a coal truck worth of power. (I do have solar PV panels on my roof, but I am hoping maybe 1000kWh or more a year saving ).
Animats 4y ago
Strange that Honda would put this out. Automotive water pumps are usually not vacuum pumps. They're down at the bottom of the cooling system pushing coolant, not up top trying to make a vacuum. This is, inevitably, covered in one of those Jam Handy movies made for Chevrolet. "Water Boy", 1936.[1] [1] https://archive.org/details/0799_Water_Boy_08_01_01_00 https://archive.org/details/0799_Water_Boy_08_01_01_00
- hatsunearu 4y ago
  Uh, this is not about cars (I thought that as well). It's about water pumps for stuff like watering plants and stuff.
- Cerium 4y ago
  Honda has a popular line of engine powered water pumps, like you may use to empty a pool or a flooded basement.

94 points by brad0 4y ago

Why there is no unit conversion with a flick of a button yet? It clearly looks that it has been translated from SI unit (e.g 1 bar or 14.7psi pressure at sea level)

ricksunny 4y ago

Well (as opposed to all the HN posts about Rust and GoLang), this is a topic I actually know a smidgen about while running a solar water pump venture out of East Africa. AMA.

simonebrunozzi 4y ago
Nobody took advantage of the opportunity! I will now. I am somewhat involved in a restoration project of a building in Italy (pet project, not my job, I'm a tech guy). We are considering installing geothermal power to warm/cool the building. Anything of what you know applies to that? There is a water canal nearby, and therefore there's a plan B that involves exchanging heat with the water in the canal.
- ricksunny 4y ago
  I wish I could speak to geothermal, but it’s just a different industry & technology (maybe it’s like the the difference between architecting a chat app vs a ride-hailing app..? :) ). Yet +1 for the sustainability approach there, always a fan of those intentions =) Things I know revolve around the content of this video I produced: https://www.youtube.com/watch?v=1ZLkmrAvAzE https://www.youtube.com/watch?v=1ZLkmrAvAzE Relevance to original article, for example, are that there are ventures around here that focus on water suction, but their scope is practically limited to surface water. We’ve focused exclusively on submersible pumps so that farmers with wells can tap their groundwater for agriculture with us.
na85 4y ago
What do you use for energy storage for dark hours?
- ricksunny 4y ago
  We avoid electrical energy storage currently. Couple of reasons: 1. Product has to be simple to be adopted effectively. Batteries or overhead tanks imply additional management overhead on the part of the farmer, and that management has to be instructed. Difficult to do in this market context. 2. Support - we’ve talked with customers of competitors who do feature a battery storage element, and they’ve complained about getting support when the battery was failing after some time. 3. Cost. We try to get customers onto the first rung of the income-generation ladder. Higher-income rungs can be achieved with incremental investment, and energy storage is a good example of this. 4. Agronomy: Water-logging plant roots consistently at night is no bueno: fungus, restricting nighttime gas transfer between the roots and soil. That said, the case for storing energy during dark hours can still be a good one, provided 1-4 are satisfied/mitigated. Early morning hours are an excellent interval to irrigate over, and the solar irradiance at those hours is often still too low to utilize the pump’s full delivery & depth (head) capability.
brad0 4y ago
I'm a bit late, but what's the technical setup? I'm curious about the panel, controller and pump. What's the wattage and parts etc. What's the final cost? Finally, what problem are you solving for?
- ricksunny 4y ago
  >Finally, what problem are you solving for? Smallhold farmer livelihoods that are underachieving relative to their capacity. Solar water pump (SWP) systems are expensive to our target market of smallhold farmers when purchased with up-front cash. Since a SWP is an income-generating appliance for its user (apply water toward grow crops -> sell crops -> $$) we focus on how the farmer can sustainably make a down-payment and pay off the SWP on a rent-to-own basis. The market and industry space is widely distributed, so we target equipping distributors to accomplish the above with farmers in their respective geographies. >what's the technical setup? > the panel Typically 120-200W collapsible solar panels that the farmer deploys daily. > controller Our IoT controller that collects local environmental & usage data that equips distributors to monitor their productivity (and so their anticipated loan performance). > and pump. DC-submersible, capable of delivering shallow groundwater accumulated over recent rainy seasons. (Power level matches the panels minus losses). Difficult to go into more detail than that without exposing more about our specific go-to-market strategy rather than anything that helps bring more farmers and distributors to the table. At the end of the day, pump models & panel sizes run the gamut in any given country's market - we help distributors select among these in their local market rather than exporting one SKU to everybody. >What's the wattage and parts etc. As above, with hosing & cabling sufficient for the groundwater depths involved. Accessories beyond that like sprinklers and a bag for carrying are generally appreciated by farmers. >What's the final cost? We have offerings between $600-$1300 paid out over a year. Of course a distributor can choose whatever payout plan they feel their local farmer market will bear.

madaxe_again 4y ago

All of the priming and vacuum issues they describe is why I swear by submersible pumps. I use a pair of deep well pumps to move water up 70m, each doing a 35m lift, with a relay tank halfway.

monkendrunky 4y ago

having small amount of solid sugar, let it mix with saliva, let it go down on throat, and then drink some water -- this has never ever ever failed me!

superb-owl 4y ago

This was fun to read. Anyone know where I might find the relevant equations/math?

na85 4y ago
Any undergraduate intro to fluid mechanics textbook will cover this material thoroughly. Looking at my bookshelf I have "Fluid Mechanics" by Frank M White from third year fluids back in the early 00s which treats this material in a chapter called Turbomachinery, building upon the preceding 10 chapters or so. If you don't want to deal with calculus you can get most of the way there with the Bernoulli equation and friends. Edit: this looks pretty good after a cursory glance: http://brennen.caltech.edu/fluidbook/ http://brennen.caltech.edu/fluidbook/
- otter-rock 4y ago
  Fundamentals of fluid mechanics by Munson et al is also good.
- timr 4y ago
  If you only get 26 feet of head, how do they manage to pump water from (say) the water tunnels that are hundreds of feet under Manhattan? Is it just that the pressure in the tunnels is well above 1atm?
  - woodruffw 4y ago
    The pressure in NYC's water tunnels brings the water up to about the 6th storey[1]. Beyond that additional pumps and tanks are needed, which is why NYC's skyline is covered in wooden water tanks (except for the newer buildings, which often have internal metal ones). [1]: https://untappedcities.com/2021/01/22/how-does-water-tower-work/ https://untappedcities.com/2021/01/22/how-does-water-tower-w...
    - timr 4y ago
      That's not what I'm referring to. Yes, the water system is pressurized (as are all), but the tunnels themselves are ~500 feet below ground [1][2]. Water is pumped to valve chambers which are themselves far (~250 feet) below ground, then again to the surface. The head pressure on a 500 foot column of water would be over 200psi. This article [3] says that the first leg of water tunnel three runs at over 300 psi, though, so maybe that's the answer. It just seems crazy. [1] https://en.wikipedia.org/wiki/New_York_City_Water_Tunnel_No._3#:~:text=upstate%20water%20supply.-,Water%20Tunnel%20No.,completed%20until%20at%20least%202026 https://en.wikipedia.org/wiki/New_York_City_Water_Tunnel_No..... [2] https://www.theverge.com/2013/10/19/4853636/underground-with-manhattans-new-water-tunnel-three-photo-essay https://www.theverge.com/2013/10/19/4853636/underground-with... [3] https://www.baltimoresun.com/news/bs-xpm-1998-08-21-1998233084-story.html https://www.baltimoresun.com/news/bs-xpm-1998-08-21-19982330...

elromulous 4y ago

Tangent: seeing the title and the Honda url, I was certain this was going to be related to the engine air pump model[1]. Since engines are limited by the amount of air they can push through, you then think of the engine as an air pump (and try to optimize around that). Although this model is fairly commonly used in the automotive industry, details online are surpassingly sparse. Taylor[2] has a bunch of details on it. [1] https://www.roadandtrack.com/car-culture/news/a29588/how-internal-combustion-engines-work/ https://www.roadandtrack.com/car-culture/news/a29588/how-int... [2] https://direct.mit.edu/books/book/4840/Internal-Combustion-Engine-in-Theory-and https://direct.mit.edu/books/book/4840/Internal-Combustion-E...

otter-rock 4y ago
That's a very common occurrence outside of software. I know a guy who is famous within his field for certain important discoveries. Later, he "discovered" something else, only to find out that it had been published decades earlier by people in an adjacent subject field, and that parts of industry had been using it for a long time. Years later, there are still no new resources about it. If you know, you know. If you don't, you don't.

sho 4y ago

> This is similar to sucking on a straw Totally random and off topic, but since it took me 40 years to learn the only 100% effective way to get rid of hiccups, this is it. You need to create an extended period of negative pressure in your oesophagus, to de-activate the vagus nerve, or whatever it's called. The reliable way to do this is to have a bottle of water and a straw. Plug your ears if possible - helps but it's not strictly necessary. Crimp the straw somewhat with your teeth. Now spend 20 or 30 seconds slowly, but with a high pressure, sucking water through that straw and swallowing it. Remember, your goal is negative pressure in the oesophagus for an extended period. It is the only reliable method and for some reason is almost completely unknown. Well, now you know! </tangent>

doliveira 4y ago
Drinking a full glass of water very quickly has never failed for me, perhaps it does something similar to your method?
madaxe_again 4y ago
Same ultimate solution, but no need for any apparatus - lung packing. I learned this incidentally while I was into freediving as a teen. Just take the deepest breath that you can, and then use your tongue and throat to pack more air into your lungs until you feel fit to burst - it may take 20-30 packs. Hold it for ten seconds, then slowly exhale - if you’ve done it right you’ll feel like a deflating air mattress. Hiccups will be gone. If they aren’t, you didn’t pack enough.
monkendrunky 4y ago
having small amount of solid sugar, let it mix with saliva, let it go down on throat, and then drink some water -- this has never ever ever failed me!
newaccount74 4y ago
> Crimp the straw somewhat with your teeth Damnit. Can't do that with the glass and metal straws we have now... > It is the only reliable method and for some reason is almost completely unknown. Well, now you know! I'm going to patent a straw with a tiny hole on one end and sell it as an anti-hiccup-device. Do you also know of a way to trigger hiccups so I can test my anti-hiccup-device?

martyvis 4y ago

I'm in the process of researching to replace my swimming pool pump. My current one nominally runs at 2850rpm and has a nominal power consumption of 1650W, but I think I measured it at around 1100W. I imagine the maximum load is when starting and also if it has to "suck" with a large head. My pump is about 0.5m above the pool level. It is a 14 year old pump that is obviously just a single phase (240V 50Hz) AC induction motor. The replacements are permanent magnet DC motor driven, with a variable speed (presumably frequency and voltage) drive can control speed from 600 to 2850rpm. After priming at full speed for a few minutes (to purge air) it looks like you can then run it at say 1300 to 1800 rpm and save a coal truck worth of power. (I do have solar PV panels on my roof, but I am hoping maybe 1000kWh or more a year saving ).

Animats 4y ago

Strange that Honda would put this out. Automotive water pumps are usually not vacuum pumps. They're down at the bottom of the cooling system pushing coolant, not up top trying to make a vacuum. This is, inevitably, covered in one of those Jam Handy movies made for Chevrolet. "Water Boy", 1936.[1] [1] https://archive.org/details/0799_Water_Boy_08_01_01_00 https://archive.org/details/0799_Water_Boy_08_01_01_00

hatsunearu 4y ago
Uh, this is not about cars (I thought that as well). It's about water pumps for stuff like watering plants and stuff.
Cerium 4y ago
Honda has a popular line of engine powered water pumps, like you may use to empty a pool or a flooded basement.