Water Pressure
- Thread starter nov0798
- Start date
Michael McSharry
Active Member
I do not have any specifics, but my first thought is to go to an auto junkyard and pick up a pressure sensor and use the A/D input device of your HA system. Something like this http://www.auberins.com/index.php?m...id=149&zenid=310748b4d1612a6683b4934dd0eea0aa
You know the funny thing is, I was thinking of using an automotive sensor on the way home tonight. The issue with most auto sensors is that I would need a 5v reference signal, but thats not the end of the world. Just not sure how I would incorporate this in to the Premise software to display the pressure.
I guess I would need some type of device that would convert the analog voltage signal into a PSI reading. The Premise software would then need to use some type of module to interface with the sensors data. The system would then need some type of chart that would compare voltage in relation to pressure, and then display that reading in Premise.
This might be easier than it sounds, I just need the technical knowledge from someone else.
I guess I would need some type of device that would convert the analog voltage signal into a PSI reading. The Premise software would then need to use some type of module to interface with the sensors data. The system would then need some type of chart that would compare voltage in relation to pressure, and then display that reading in Premise.
This might be easier than it sounds, I just need the technical knowledge from someone else.
apostolakisl
Senior Member
Check out your Elk manual, I think it has an input that will accept (and interpret) variable voltage input. I swear I saw that when I was installing mine.
What is it that you are needing to monitor your water pressure for?
What is it that you are needing to monitor your water pressure for?
Hello Novo,
As Lou queried, what are you trying to accomplish with the pressure measurement?
I ask because hydraulic systems are extremely noisy (low damping) and have a habit of producing very high pressure spikes that can easily degrade or take out a sensor. I like the sensor that Michael linked to from a construction standpoint, but the range appears a little low. The sensor is a 70 PSIA unit (Absolute) and you will be measuring Gauge (referenced to atmosphere) pressures. Most households operate from 45 - 65 psig. In absolute pressure, that's 59.7 to 79.7 PSIA (add approximately 14.7 PSI to convert from Gauge to Absolute).
The unit has a proof pressure range of 200% which implies that it will not suffer damage up to 140 PSIA. Although the unit is "ruggedized" for automotive applications, I doubt it will take repeated over-pressurization to this level. In short, I think you will need a higher range unit (120 PSIG with 200% proof). Unfortunately, up-sizing the sensor will reduce your resolution and accuracy. Sorry but that's the nature of the beast.
Once you've found a range that will work in your system, you'll need to figure out a way to deal with the noise. Every time you open/close a valve in your home you will get pressure spikes. You may be able to minimize these by locating the sensor on top of a air filled stand tube. You'll need to find a way of filtering and/or averaging these out to be able to make sense of the information. If you have a well you will also need to deal with pump noise.
Make no mistake, this will be quite a bit of work. It may also be quite a bit of fun. It really depends on what you're trying to accomplish.
As Lou queried, what are you trying to accomplish with the pressure measurement?
I ask because hydraulic systems are extremely noisy (low damping) and have a habit of producing very high pressure spikes that can easily degrade or take out a sensor. I like the sensor that Michael linked to from a construction standpoint, but the range appears a little low. The sensor is a 70 PSIA unit (Absolute) and you will be measuring Gauge (referenced to atmosphere) pressures. Most households operate from 45 - 65 psig. In absolute pressure, that's 59.7 to 79.7 PSIA (add approximately 14.7 PSI to convert from Gauge to Absolute).
The unit has a proof pressure range of 200% which implies that it will not suffer damage up to 140 PSIA. Although the unit is "ruggedized" for automotive applications, I doubt it will take repeated over-pressurization to this level. In short, I think you will need a higher range unit (120 PSIG with 200% proof). Unfortunately, up-sizing the sensor will reduce your resolution and accuracy. Sorry but that's the nature of the beast.
Once you've found a range that will work in your system, you'll need to figure out a way to deal with the noise. Every time you open/close a valve in your home you will get pressure spikes. You may be able to minimize these by locating the sensor on top of a air filled stand tube. You'll need to find a way of filtering and/or averaging these out to be able to make sense of the information. If you have a well you will also need to deal with pump noise.
Make no mistake, this will be quite a bit of work. It may also be quite a bit of fun. It really depends on what you're trying to accomplish.
Well,
The other day my wife called and said, wow the pressure in the house is really low. I said, wel maybe there is an issue with the street pressure from the water company. She also stated that it sounded like someone was hammering on the pipes when the water ran. I thought this was strange. When I got home, I heard the issue she was speaking about, and eventually traced it down to the pressure regulator in the system. For some reason, the little nut that keeps the adjuster from backing off had come loose, and the pressure in the house had dropped to a really low level like 20psi. The hammering was coming from the pressure regulator. I thought it would be nice to have had a rule that when the pressure went below a certain level, it would alert you. This also may have other uses.
More or less I just want to monitor it just because! I guess thats like alot of the stuff we do.
The other day my wife called and said, wow the pressure in the house is really low. I said, wel maybe there is an issue with the street pressure from the water company. She also stated that it sounded like someone was hammering on the pipes when the water ran. I thought this was strange. When I got home, I heard the issue she was speaking about, and eventually traced it down to the pressure regulator in the system. For some reason, the little nut that keeps the adjuster from backing off had come loose, and the pressure in the house had dropped to a really low level like 20psi. The hammering was coming from the pressure regulator. I thought it would be nice to have had a rule that when the pressure went below a certain level, it would alert you. This also may have other uses.
More or less I just want to monitor it just because! I guess thats like alot of the stuff we do.
apostolakisl
Senior Member
The oil pressure sending unit (as it is called) in my car reads pressures up over 100psi at times and supposedly maxes out at 160psi. It is a standard 5 volt deal but I don't know if water would be a problem as compared to oil. It has a threaded post so you would need to drill a hole in the side of a metal pipe and cut the correct thread to mount it (I am assuming the thread is not the same as a standard pipe thread, but I suppose you could be lucky).
And after thinking about it, I believe the way you get the Elk to accept the variable input voltage is by inputting it as a temperature sensor. You would need to modify the signal to get it into the proper range to accurately read the pressure.
And after thinking about it, I believe the way you get the Elk to accept the variable input voltage is by inputting it as a temperature sensor. You would need to modify the signal to get it into the proper range to accurately read the pressure.
Lou,
Thats exactly what I was thinking. An oil sending unit would probably work perfectly, and it wouldnt matter if it was oil or water. As for the mounting, yes I could sweat in a copper T and then a pipe fitting into that, that the sensor would screw into. I could always use the electronic sender that converts the pressure to a reading for you, but again how do you get that data to display in Premise, or other HA software applications?
Thats exactly what I was thinking. An oil sending unit would probably work perfectly, and it wouldnt matter if it was oil or water. As for the mounting, yes I could sweat in a copper T and then a pipe fitting into that, that the sensor would screw into. I could always use the electronic sender that converts the pressure to a reading for you, but again how do you get that data to display in Premise, or other HA software applications?
apostolakisl
Senior Member
I see on your list that you have an Elk m1(g). I was reading )I think on this board) where other people were modifying variable voltage devices and having the Elk read them as though they were temperature probes. Once into Elk you could write rules to respond to different readings.
You would need to find out what the Elk expects as far as voltage for a few temperatures and using resistors and such callibrate the numbers. Alternatively and assuming the normal output from the oil sending unit is within Elk range, you could simply figure out a conversion factor (like multiply time 1.4 or something). The only concern I have about an oil pressure unit in water is that it might rust after a while. I have no doubt that at first it would work perfectly.
Your profile says you have 1-wire. Is there a 1-wire device that can take a 4-20mA signal and convert it to something that the M1G will understand? If so, Dwyer Instruments sells pressure transmitters for about $65 that would work.
An M1G zone can be defined as analog (type=34), which means it will accept a 0-12Vdc signal and convert it to an analog value. You can then set up rules that are based on the analog value. It looks like an analog zone cannot be the "target" of the "whenever" part of the rule (it won't show up in the dropdown list of zones). I can only get it to show up in the "and" part of the rule. Download the M1G manual/pdf and do a search on "analog". Very little info, but it is there.
An M1G zone can be defined as analog (type=34), which means it will accept a 0-12Vdc signal and convert it to an analog value. You can then set up rules that are based on the analog value. It looks like an analog zone cannot be the "target" of the "whenever" part of the rule (it won't show up in the dropdown list of zones). I can only get it to show up in the "and" part of the rule. Download the M1G manual/pdf and do a search on "analog". Very little info, but it is there.
apostolakisl
Senior Member
Water has oxygen dissolved in it so it would still rust if it was made out of something that rusts. I just can't be sure what it is made out of and someone designing this thing to be in oil certainly wouldn't be thinking about rust since oil seals the surface from oxygen. Worst case the thing stops working in a year or two and you replace it. My guess is that you are right and that the metal is aluminum since it is probably designed to screw into an aluminum engine block and they would want it to expand/contract in step with the engine.