Post by thread:[EE] cheap pressure sensor for water pump

Hi, I'm constantly having trouble with pressure switch of a water pump, which is supplying water from a well for a house and garden. Setup is far from optimal, and seems like normal, membrane-activated switches are having trouble with this. I am sure there are better switches available somewhere, but I had an idea to build one by myself, using a PIC. That way I could have better control of ON and OFF pressures, and hysteresis, probably also some kind of dynamic self-adjusting, to cope with completely different situations of supplying just home, vs supplying water for garden. Soft start of a pump motor could be implemented easily too. Any ideas what cheap pressure sensor could be used? Sensor has a direct contact with water. Some kind of a digital output would be best, but i can live with analog signal too. Best if that sensor is widely available, that is, used in some consumer equipment. Somebody recommended to use oil pressure sensor from a car, that has continuous-signal sensor, not just a pressure switch, but I do not have an exact car model that uses this kind of sensor. Probably sensor, designed to contact with oil, would not live very long with water, but it's ok to replace it sometimes if it's cheap enough. I'm interested in pressures between 1 and 6 bar, or so. -- KP

Maybe some of these will help: http://www.ebay.com/sch/i.html?_sacat=0&_nkw=oil%20sensor%20pressure&_sop=15 Cheers, Mario At 10.57 2012.06.13, you wrote: {Quote hidden}>Hi, > >I'm constantly having trouble with pressure switch of a water pump, >which is supplying water from a well for a house and garden. Setup is >far from optimal, and seems like normal, membrane-activated switches >are having trouble with this. I am sure there are better switches >available somewhere, but I had an idea to build one by myself, using a >PIC. That way I could have better control of ON and OFF pressures, and >hysteresis, probably also some kind of dynamic self-adjusting, to cope >with completely different situations of supplying just home, vs >supplying water for garden. Soft start of a pump motor could be >implemented easily too. > >Any ideas what cheap pressure sensor could be used? Sensor has a >direct contact with water. >Some kind of a digital output would be best, but i can live with >analog signal too. >Best if that sensor is widely available, that is, used in some >consumer equipment. > >Somebody recommended to use oil pressure sensor from a car, that has >continuous-signal sensor, not just a pressure switch, but I do not >have an exact car model that uses this kind of sensor. >Probably sensor, designed to contact with oil, would not live very >long with water, but it's ok to replace it sometimes if it's cheap >enough. > >I'm interested in pressures between 1 and 6 bar, or so. > >-- >KPL >

On Wed, Jun 13, 2012 at 1:57 AM, KPL <spam_OUTkpl.listesTakeThisOuTgmail.com> wrote: > > Somebody recommended to use oil pressure sensor from a car, that has > continuous-signal sensor, not just a pressure switch, but I do not > have an exact car model that uses this kind of sensor. > Probably sensor, designed to contact with oil, would not live very > long with water, but it's ok to replace it sometimes if it's cheap > enough. Something like this? Not sure if it meets the cheap enough requirement. :) http://www.amazon.com/Sunpro-CP7577-Oil-Pressure-Sender/dp/B00029JXMA/ref=sr_1_1?ie=UTF8&qid=1339607287&sr=8-

Some where in the system there should be a pressure tank. The pressure switch should be as close as possible to the tank. If there is a filter in the system, it should be as close to the tank input as possible. The wells around here are deep enough to require submersible pumps. The pressure tanks have a diaphragm and an airspace. They sometimes need replacement. The pressure switches last a very long time. I have lived here for nearly 20 years and not needed a replacement. On 6/13/2012 4:57 AM, KPL wrote: {Quote hidden}> Hi, > > I'm constantly having trouble with pressure switch of a water pump, > which is supplying water from a well for a house and garden. Setup is > far from optimal, and seems like normal, membrane-activated switches > are having trouble with this. I am sure there are better switches > available somewhere, but I had an idea to build one by myself, using a > PIC. That way I could have better control of ON and OFF pressures, and > hysteresis, probably also some kind of dynamic self-adjusting, to cope > with completely different situations of supplying just home, vs > supplying water for garden. Soft start of a pump motor could be > implemented easily too. > > Any ideas what cheap pressure sensor could be used? Sensor has a > direct contact with water. > Some kind of a digital output would be best, but i can live with > analog signal too. > Best if that sensor is widely available, that is, used in some > consumer equipment. > > Somebody recommended to use oil pressure sensor from a car, that has > continuous-signal sensor, not just a pressure switch, but I do not > have an exact car model that uses this kind of sensor. > Probably sensor, designed to contact with oil, would not live very > long with water, but it's ok to replace it sometimes if it's cheap > enough. > > I'm interested in pressures between 1 and 6 bar, or so. > -- John Ferrell W8CCW “During times of universal deceit, Telling the TRUTH becomes a revolutionary act” George Orwell

yes, some of them should be the right kind, just usually selles have no idea if their sensor is a continuous-signal sensor or just a pressure switch. Here you can see there is "switch" mentioned at several items, and just sensor at others, while they look about the same. At car parts store they know only what car the particular sensor is mentioned for, but have no idea if it's a switch or what. On Wed, Jun 13, 2012 at 4:32 PM, Electron <.....electron2k4KILLspam@spam@infinito.it> wrote: {Quote hidden}> > Maybe some of these will help: > http://www.ebay.com/sch/i.html?_sacat=0&_nkw=oil%20sensor%20pressure&_sop=15 > > Cheers, > Mario > > > At 10.57 2012.06.13, you wrote: >>Hi, >> >>I'm constantly having trouble with pressure switch of a water pump, >>which is supplying water from a well for a house and garden. Setup is >>far from optimal, and seems like normal, membrane-activated switches >>are having trouble with this. I am sure there are better switches >>available somewhere, but I had an idea to build one by myself, using a >>PIC. That way I could have better control of ON and OFF pressures, and >>hysteresis, probably also some kind of dynamic self-adjusting, to cope >>with completely different situations of supplying just home, vs >>supplying water for garden. Soft start of a pump motor could be >>implemented easily too. >> >>Any ideas what cheap pressure sensor could be used? Sensor has a >>direct contact with water. >>Some kind of a digital output would be best, but i can live with >>analog signal too. >>Best if that sensor is widely available, that is, used in some >>consumer equipment. >> >>Somebody recommended to use oil pressure sensor from a car, that has >>continuous-signal sensor, not just a pressure switch, but I do not >>have an exact car model that uses this kind of sensor. >>Probably sensor, designed to contact with oil, would not live very >>long with water, but it's ok to replace it sometimes if it's cheap >>enough. >> >>I'm interested in pressures between 1 and 6 bar, or so. >> >>-- >>KPL >>

Pump is not a submersible type, and is located near the well. Everything else is located some distance away, with switch mounted just before the pressure vessel; Everything except the switch and pump was just replaced. I know about effects caused by water inertia in case of incorrect location of components, and that is not a problem. Most probably the switch you are using for 20 years was not made in china. Those that pretend to be made in Europe cost much more, and are not easy to find. Sorry, this is becoming quite bit off topic. The main idea is - I do not like that mechanical switch, and was dreaming about digitally controlled substitute for quite some time. Component sellers usually do not mention in their catalogs what medium their sensors are meant for, and it's quite a task to search all those datasheets. Usually those sensors cost quite a lot, but I do not need that high precision, since most probably any of them will be give more repeatable results than the mechanical switch. On Wed, Jun 13, 2012 at 9:36 PM, John Ferrell <jferrell13KILLspamtriad.rr.com> wrote: {Quote hidden}> Some where in the system there should be a pressure tank. The pressure > switch should be as close as possible to the tank. If there is a filter > in the system, it should be as close to the tank input as possible. The > wells around here are deep enough to require submersible pumps. The > pressure tanks have a diaphragm and an airspace. They sometimes need > replacement. The pressure switches last a very long time. I have lived > here for nearly 20 years and not needed a replacement. > -- KP

Just an idea, did you think using an elevated tank and a simple on/off switch to fill it ? cheers Rodolfo -----Mensaje original----- De: .....piclist-bouncesKILLspam.....mit.edu [EraseMEpiclist-bouncesspam_OUTTakeThisOuTmit.edu]En nombre de KPL Enviado el: Miercoles, 13 de Junio de 2012 01:34 p.m. Para: Microcontroller discussion list - Public. Asunto: Re: [EE] cheap pressure sensor for water pump Pump is not a submersible type, and is located near the well. Everything else is located some distance away, with switch mounted just before the pressure vessel; Everything except the switch and pump was just replaced. I know about effects caused by water inertia in case of incorrect location of components, and that is not a problem. Most probably the switch you are using for 20 years was not made in china. Those that pretend to be made in Europe cost much more, and are not easy to find. Sorry, this is becoming quite bit off topic. The main idea is - I do not like that mechanical switch, and was dreaming about digitally controlled substitute for quite some time. Component sellers usually do not mention in their catalogs what medium their sensors are meant for, and it's quite a task to search all those datasheets. Usually those sensors cost quite a lot, but I do not need that high precision, since most probably any of them will be give more repeatable results than the mechanical switch. On Wed, Jun 13, 2012 at 9:36 PM, John Ferrell <jferrell13spam_OUTtriad.rr.com> wrote: {Quote hidden}> Some where in the system there should be a pressure tank. The pressure > switch should be as close as possible to the tank. If there is a filter > in the system, it should be as close to the tank input as possible. The > wells around here are deep enough to require submersible pumps. The > pressure tanks have a diaphragm and an airspace. They sometimes need > replacement. The pressure switches last a very long time. I have lived > here for nearly 20 years and not needed a replacement. > -- KP

Look at this link: www.ebay.com/itm/Automatic-Water-Pump-Pressure-Controller-Electric-El ectronic-Switch-Control-Unit-/170850300264?pt=BI_Pumps&hash=item27c778b168#h t_5495wt_952 Ready to use electronic switch up to 10 bar for $ 38.00 and free shipping. Rodolfo -----Mensaje original----- De: @spam@piclist-bouncesKILLspammit.edu [KILLspampiclist-bouncesKILLspammit.edu]En nombre de Nily Enviado el: Miercoles, 13 de Junio de 2012 02:11 p.m. Para: Microcontroller discussion list - Public. Asunto: RE: [EE] cheap pressure sensor for water pump Just an idea, did you think using an elevated tank and a simple on/off switch to fill it ? cheers Rodolfo -----Mensaje original----- De: RemoveMEpiclist-bouncesTakeThisOuTmit.edu [spamBeGonepiclist-bouncesspamBeGonemit.edu]En nombre de KPL Enviado el: Miercoles, 13 de Junio de 2012 01:34 p.m. Para: Microcontroller discussion list - Public. Asunto: Re: [EE] cheap pressure sensor for water pump Pump is not a submersible type, and is located near the well. Everything else is located some distance away, with switch mounted just before the pressure vessel; Everything except the switch and pump was just replaced. I know about effects caused by water inertia in case of incorrect location of components, and that is not a problem. Most probably the switch you are using for 20 years was not made in china. Those that pretend to be made in Europe cost much more, and are not easy to find. Sorry, this is becoming quite bit off topic. The main idea is - I do not like that mechanical switch, and was dreaming about digitally controlled substitute for quite some time. Component sellers usually do not mention in their catalogs what medium their sensors are meant for, and it's quite a task to search all those datasheets. Usually those sensors cost quite a lot, but I do not need that high precision, since most probably any of them will be give more repeatable results than the mechanical switch. On Wed, Jun 13, 2012 at 9:36 PM, John Ferrell <TakeThisOuTjferrell13EraseMEspam_OUTtriad.rr.com> wrote: {Quote hidden}> Some where in the system there should be a pressure tank. The pressure > switch should be as close as possible to the tank. If there is a filter > in the system, it should be as close to the tank input as possible. The > wells around here are deep enough to require submersible pumps. The > pressure tanks have a diaphragm and an airspace. They sometimes need > replacement. The pressure switches last a very long time. I have lived > here for nearly 20 years and not needed a replacement. > -- KP

Hello, I'd always found that the Motorola (apparently now marketed as Freescale Semiconductor) sensor fit that bill quite well.. Check out the MPXV5050 ($13.64 each from Newark).. http://www.newark.com/jsp/search/productdetail.jsp?SKU=75C3918&&CMP=AFC-SF-T11 Many ranges and options to choose from. Best regards, Mike On Wed, Jun 13, 2012 at 4:57 AM, KPL <RemoveMEkpl.listesTakeThisOuTgmail.com> wrote: {Quote hidden}> Hi, > > I'm constantly having trouble with pressure switch of a water pump, > which is supplying water from a well for a house and garden. Setup is > far from optimal, and seems like normal, membrane-activated switches > are having trouble with this. I am sure there are better switches > available somewhere, but I had an idea to build one by myself, using a > PIC. That way I could have better control of ON and OFF pressures, and > hysteresis, probably also some kind of dynamic self-adjusting, to cope > with completely different situations of supplying just home, vs > supplying water for garden. Soft start of a pump motor could be > implemented easily too. > > Any ideas what cheap pressure sensor could be used? Sensor has a > direct contact with water. > Some kind of a digital output would be best, but i can live with > analog signal too. > Best if that sensor is widely available, that is, used in some > consumer equipment. > > Somebody recommended to use oil pressure sensor from a car, that has > continuous-signal sensor, not just a pressure switch, but I do not > have an exact car model that uses this kind of sensor. > Probably sensor, designed to contact with oil, would not live very > long with water, but it's ok to replace it sometimes if it's cheap > enough. > > I'm interested in pressures between 1 and 6 bar, or so. > > -- > KPL >

What brand do you have that's failing. Around here everyone uses a Square D, line voltage pressure switch, and it's next to never they go bad. But if going the PIC route, check out this family @ $15 http://www.mouser.com/ProductDetail/Freescale-Semiconductor/MPX5700GP1/?qs=r8OyiFxb6Rc9Emm4NZHQFL0WwDp2TJGWwqXdJbUhZqM%3d On 6/13/2012 5:38 PM, Nily wrote: {Quote hidden}> Look at this link: > www.ebay.com/itm/Automatic-Water-Pump-Pressure-Controller-Electric-El > ectronic-Switch-Control-Unit-/170850300264?pt=BI_Pumps&hash=item27c778b168#h > t_5495wt_952 > > Ready to use electronic switch up to 10 bar for $ 38.00 and free shipping.. > > Rodolfo > > -----Mensaje original----- > De: piclist-bouncesEraseME.....mit.edu [EraseMEpiclist-bouncesmit.edu]En nombre de > Nily > Enviado el: Miercoles, 13 de Junio de 2012 02:11 p.m. > Para: Microcontroller discussion list - Public. > Asunto: RE: [EE] cheap pressure sensor for water pump > > > Just an idea, did you think using an elevated tank and a simple on/off > switch to fill it ? > > cheers > > Rodolfo > > -----Mensaje original----- > De: RemoveMEpiclist-bouncesEraseMEEraseMEmit.edu [RemoveMEpiclist-bouncesspam_OUTKILLspammit.edu]En nombre de > KPL > Enviado el: Miercoles, 13 de Junio de 2012 01:34 p.m. > Para: Microcontroller discussion list - Public. > Asunto: Re: [EE] cheap pressure sensor for water pump > > > Pump is not a submersible type, and is located near the well. > Everything else is located some distance away, with switch mounted > just before the pressure vessel; Everything except the switch and pump > was just replaced. I know about effects caused by water inertia in > case of incorrect location of components, and that is not a problem. > Most probably the switch you are using for 20 years was not made in > china. Those that pretend to be made in Europe cost much more, and are > not easy to find. > Sorry, this is becoming quite bit off topic. > > The main idea is - I do not like that mechanical switch, and was > dreaming about digitally controlled substitute for quite some time. > Component sellers usually do not mention in their catalogs what medium > their sensors are meant for, and it's quite a task to search all those > datasheets. Usually those sensors cost quite a lot, but I do not need > that high precision, since most probably any of them will be give more > repeatable results than the mechanical switch. > > On Wed, Jun 13, 2012 at 9:36 PM, John Ferrell<RemoveMEjferrell13TakeThisOuTspamtriad.rr.com> > wrote: > >> Some where in the system there should be a pressure tank. The pressure >> switch should be as close as possible to the tank. If there is a filter >> in the system, it should be as close to the tank input as possible. The >> wells around here are deep enough to require submersible pumps. The >> pressure tanks have a diaphragm and an airspace. They sometimes need >> replacement. The pressure switches last a very long time. I have lived >> here for nearly 20 years and not needed a replacement. >> >> > > > > -- > KPL >

Thanks, I do not see in the datasheet what medium they are designed for - somehow I am not quite sure they will be happy to have direct contact with water. Otherwise, I see them available for 16 EUR, which is fine. Probably I should just try one, since I can actually leave original switch attached in case if my design fails. On Thu, Jun 14, 2012 at 2:14 AM, Michael Klein <EraseMEpointfreedomspamspamBeGonegmail.com> wrote: {Quote hidden}> Hello, > > I'd always found that the Motorola (apparently now marketed as Freescale > Semiconductor) sensor fit that bill quite well.. > > Check out the MPXV5050 ($13.64 each from Newark).. > http://www.newark.com/jsp/search/productdetail.jsp?SKU=75C3918&&CMP=AFC-SF-T11 > > Many ranges and options to choose from. > Best regards, > > Mike -- KP

Thanks. Seems like I will have to try another car parts sellers, probably someone will find me one of these. On Thu, Jun 14, 2012 at 8:08 PM, Brooke Clarke <RemoveMEbrookeKILLspampacific.net> wrote: {Quote hidden}> Hi Alex: > > A week ago I wanted to see what my house water pressure was and so looked for a low cost water pressure sensor, but no luck. > After spending some time in the auto parts store finally got an oil pressure sender that was for an analog gauge rather > than just a switch. > I turns out to be calibrated (using a patented method) at 1 Ohm per PSI. Â This works well with the Fluke 87 DMM in > Min-Max mode. > See: Â http://www.prc68.com/I/WaterPressure.html > http://www.prc68.com/I/DMM.shtml > > -- > Have Fun, > > Brooke Clarke > http://www.PRC68.com > >

Hi, I've used them successfully totally submerged in water. I doubt you'd have a problem. Good luck. On Thu, Jun 14, 2012 at 6:07 AM, KPL <kpl.listesSTOPspamspam_OUTgmail.com> wrote: {Quote hidden}> Thanks, > I do not see in the datasheet what medium they are designed for - > somehow I am not quite sure they will be happy to have direct contact > with water. Otherwise, I see them available for 16 EUR, which is fine. > Probably I should just try one, since I can actually leave original > switch attached in case if my design fails. > > On Thu, Jun 14, 2012 at 2:14 AM, Michael Klein <spamBeGonepointfreedomSTOPspamEraseMEgmail.com> > wrote: > > Hello, > > > > I'd always found that the Motorola (apparently now marketed as Freescale > > Semiconductor) sensor fit that bill quite well.. > > > > Check out the MPXV5050 ($13.64 each from Newark).. > > > www.newark.com/jsp/search/productdetail.jsp?SKU=75C3918&&CMP=AFC-SF-T11 > > > > Many ranges and options to choose from. > > Best regards, > > > > Mike > > -- > KPL >