house water main supply pressure psi- best way?

Looking to get pressure off my house water main supply, I saw an article on using pressure profiles to determine what device is using water. Thought it would be fun to try counting toilet flushes ::slight_smile:

Googling around it seems that an oil pressure sender might be a cheap way to do this - but I didn't find a whole lot of details other than the idea.

Does anyone have suggestions for an car oil pressure sender - I'm also open to something completely different?
I was looking at this one for about $19 and does 0 to 100psi.

http://www.autozone.com/autozone/accessories/Sunpro-1-8-in-NPT-oil-pressure-sender-with-1-4-in-NPT-adapter-for-electrical-oil-gauges/_/N-269r?counter=0&filterByKeyWord=oil+pressure&fromString=search&itemIdentifier=87626_0_0_

thanks for the input!

so far the cheapest that I've found is about $80 to 125 and that's more then I'm willing to spend at this point with out having a clear plan but 125 bucks is cheaper then a doctor's visit!

I've never seen anything over 65psig at my house the doz times that I've checked - but I'm a bit elevated and don't know what the water dept does when I'm not checking...

I'll keep looking for something with a higher range, safer and cheaper.

As a side note from Omega, old, established process control sensor manufacturer and source for lots of neat information you don't usually think about when you first go go to measure stuff; http://www.omega.com/techref/waterhammer.html

Honeywell sensors for 0-150psi are available in the $45-50 range, I2C, if you want analog, you might drop $10-15 off that price.
This one http://www.mouser.com/ProductDetail/Honeywell/HSCDANN150PG2A5/?qs=sGAEpiMZZMvhQj7WZhFIADdMYlPf938%2FcyRCS4VwdK4%3D is mentioned for use in hospital equipment in the datasheet.

If you're interested in counting toilet flushes, you might be better measuring flow rather than pressure. Toilets filling will have a very pronounced flow pattern whereas pressure can be hit and miss if you have a large bore supply - the pressure barely moves when the toilet starts filling. Flow sensors seem to be easier to come across too (since they are widely used in water meters).

I found this which uses a cheap piezo transducer to measure flow without breaking into pipes, it would work best where the flow makes some noise I suspect.

No guarantees to its accuracy.......

Slightly up-market flow sensor which won't break the bank but does require breaking into pipework :

http://www.seeedstudio.com/depot/water-flow-sensor-p-635.html?cPath=6&zenid=594b89701c7a2015a13064b67aed4f44

Or for simply counting toilet flushes (since you don't care about measuring water volume used) you could use either a reed switch / magnet combo attached to the arm behind the flush button, or a float switch like this:

http://www.jaycar.com.au/productView.asp?ID=SF0920

Piece of cake to fit that inside the cistern and count input transitions using an Arduino.

Jon
Freetronics: www.freetronics.com

Oh, I just realised that you're probably not doing this specifically to solve the problem of counting toilet flushes, you're just using that as an application to experiment with detecting specific water-consumption events by analysing the varying water pressure profile.

That's a much more interesting problem!

Please ignore my float switch suggestion.

Jon

thanks all for the reply's

the Honeywell item is interesting - but the spec sheet says air/gas - there's like 10000 listed so I'll keep looking

anyone found a cheap 3/4" meter?

correct I was interested in detecting different device events with the pressure profile - I read a short news/pr article and thought it was interesting - I think the article was actually on high freq noise profiles with starting and running of electrical devices - but that's way beyond my capacity - in digging I found that it also applied to indoor pumped devices but with pressure - and that sounds like it's within my capacity... and there was also one with dp sensors in a central hvac filter to detect people entering and leaving different rooms via pressure change profile responses from the return ducts (I had no interest in that one)

looks like it's the <$3 piezo to see if my main water pipe gives any kind of feedback to water events. I have pvc and cpvc and wonder about damping...

I thought I'd advise that if you do decide to implement some form of inline sensor, be sure to also bridge the spliced pipe work with a earth/ground bonding strap in order to comply with building regulations.