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adding pressure transducer to the piping

Does anyone have experience adding a pressure transducer into the piping? Something like this https://www.ebay.com/itm/1-8NPT-Stainless-Steel-Pressure-Transducer-Sender-Sensor-0-4-5V-Oil-Fuel-Air-stw-/263104502679 I see other pressure transducers that are really, really expensive. I'm concerned about the quality of this sensor but I admit I love the price.

@NY_Rob this seems like something you might have done/tried.
DIY'er ... ripped out a perfectly good forced-air furnace and replaced it with hot water & radiators.

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 12,364
    You have to get one that has the proper pressure range for what you are doing. Also, read the instructions. You may be restricted as to mounting positions. If on steam check to see if a pigtail or water seal is required. The transduce must be suitable for the liquid/gas you are sensing. And the current/voltage must be correct for the controls your wired to
  • NY_Rob
    NY_Rob Member Posts: 1,370
    @Boon .... interesting item, haven't tried one... yet :)
    Are you looking to measure pressure differentials to calculate flow rate? I'd be interested in them for that application.
    It would be a fun Arduino project since you know the sensor voltage output vs. pressure. The Arduino could do the math and present the results on a LCD screen.

    I have a couple of project ahead of me...

    I recently picked up an 8 probe/8-channel USB/BT temperature data logger to analyze system cycling, haven't set it up yet.

    Last tech item I bought was one of those Bluetooth borescopes with internal LED. It was under $40 on Amazon. I'm trying to get the spec on the I.D. of the firetubes in the combustion chamber of the HX of the HTP UFT-80W to see if the 9mm dia. borescope lens will fit into the tubes for inspection vs. tearing it down and cleaning it whether it needs it or not. Could save hours of work if cleaning is not needed.

  • Boon
    Boon Member Posts: 256
    I was going to start by sending a text message when pressure drops below a threshold. Calculating flow rate is way more sexy.

    I also have another project in which I need to calculate the volume of water in a cistern. I was hoping to send one of these to the bottom of the cistern, read the static pressure and calculate the volume.
    DIY'er ... ripped out a perfectly good forced-air furnace and replaced it with hot water & radiators.
  • NY_Rob
    NY_Rob Member Posts: 1,370
    ^ Good stuff!

    I have those sweet Webstone ISO flanges with purge ports on both of my pumps. It would be easy to go from hose bib to 1/8" npt for the pressure sensor, open the purge ports and instant pressure readings on both sides of the pump.....





    Boon
  • NY_Rob
    NY_Rob Member Posts: 1,370
    Anyone have the formula handy for calculating flow rate using the differential pressure on in/out sides of a pump?

    In a typical 15psi (static) system with 1" copper pipe what's the differential pressure between pump input and output with say 4gpm flow?
  • Boon
    Boon Member Posts: 256
    I did some googling and found some equations that include pipe size, temperature, etc. what concerned me most was a footnote that said the equation would only work for a horizontal run. That confuses me.
    DIY'er ... ripped out a perfectly good forced-air furnace and replaced it with hot water & radiators.
  • NY_Rob
    NY_Rob Member Posts: 1,370
    I would think in a closed loop it wouldn't make a difference?
  • Boon
    Boon Member Posts: 256
    oh good call I bet that footnote was regarding open system. I'm ordering these.
    DIY'er ... ripped out a perfectly good forced-air furnace and replaced it with hot water & radiators.
  • NY_Rob
    NY_Rob Member Posts: 1,370
    Any idea on the pressure differential in my example above?

    Just wondering if these sensors have the resolution necessary at the pressures and volume our systems run at? If we're talking a couple of PSI differential, great... but if we're talking about .2 PSI difference at 4GPM then these sensors may not work out.
  • Zman
    Zman Member Posts: 7,375
    NY_Rob said:

    Anyone have the formula handy for calculating flow rate using the differential pressure on in/out sides of a pump?

    In a typical 15psi (static) system with 1" copper pipe what's the differential pressure between pump input and output with say 4gpm flow?

    You just use the manufactures pump curve. Convert to head, (psi x 2.31) and look at the pump curve to see how many GPM.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • RPK
    RPK Member Posts: 95
    edited February 2018
    This is what we use to measure differential pressure on variable flow systems to control pump speed (on VFDs). They come in a variety of differential pressure ranges (0-1psid is the lowest available). They are certainly a bit pricier than the single point transducers Boon linked to on ebay. 0-10vdc or 4-20ma outputs are available.

    https://www.setra.com/products/pressure/model-230-wet-to-wet-pressure-transducer
  • NY_Rob
    NY_Rob Member Posts: 1,370
    edited February 2018
    Zman said:

    NY_Rob said:

    Anyone have the formula handy for calculating flow rate using the differential pressure on in/out sides of a pump?

    In a typical 15psi (static) system with 1" copper pipe what's the differential pressure between pump input and output with say 4gpm flow?

    You just use the manufactures pump curve. Convert to head, (psi x 2.31) and look at the pump curve to see how many GPM.
    Thanks, great idea!

    But which PSI reading do we use? Before the pump,after the pump, the differential between the two, after the pump less static pressure?
  • Zman
    Zman Member Posts: 7,375
    The differential pressure between the two.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    NY_RobBoon
  • NY_Rob
    NY_Rob Member Posts: 1,370
    edited February 2018
    Thanks @Zman,
    That's super easy to work with!

    Everyone keeps stating that the GPM displayed on the Grundfos Alpha is inaccurate... guess we'll see if that's true.

    Just ordered 2 sensors from ebay and the hose bib adapter(s) to connect them to the Webstone drain ports on my pump flanges.
  • Boon
    Boon Member Posts: 256
    Dang you’re gonna beat me to it Rob. Takes me like two weeks after I order anything to even remember that I ordered it let alone do anything with it.
    DIY'er ... ripped out a perfectly good forced-air furnace and replaced it with hot water & radiators.
  • NY_Rob
    NY_Rob Member Posts: 1,370
    edited February 2018
    Lol... well, the sensors are coming from Hong Kong (three weeks)... so it's no race.. .it's a crawl to the finish line :)

    It's fortunate I have the Webstone pump flanges with the drain ports, will make it quick and easy to connect the sensors without opening up the system.

    Actually Boon, I have to thank you for introducing me to those sensors.. I've really want to clock the flow through my indirect for some time now. I currently have the three speed Grundfos pump on speed II (determined by loop length, indirect and HX head and pump curve), but I really want to get a true reading on it to make sure I'm not over or under pumping it through the UFT's HX.