What did I buy ?

What did I buy ?

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Viewing 25 posts - 1 through 25 (of 33 total)
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  • #839318
    Michael Gilligan
    Participant
      @michaelgilligan61133

      Picked this up cheaply …

      I will post more photos when I’ve removed some of the grime.

      … the shrivelled squeezy bottle has a label which may possibly give us a clue, but I don’t hold out much hope.

       

      MichaelG.

       

      #839322
      Michael Gilligan
      Participant
        @michaelgilligan61133

        The mighty Google tells me:

        .

        IMG_1450

        #839323
        Robert Atkinson 2
        Participant
          @robertatkinson2

          No photo visible here. Looks like the forum bug is still there.

          Robert.

          #839324
          Michael Gilligan
          Participant
            @michaelgilligan61133

            Don’t understand what the forum has done to my post … Grrr!!

            The subject line included the words CASELLA, LONDON within angled brackets

            and there were two photos

            Maybe they will suddenly appear … or maybe not.

            MichaelG.

            #839327
            Michael Gilligan
            Participant
              @michaelgilligan61133
              #839329
              Grindstone Cowboy
              Participant
                @grindstonecowboy

                Anything between angled brackets has probably been interpreted as some form of HTML and disappeared into a forum black hole.

                Test – putting the words “black hole” between angled brackets here <black hole>

                Rob

                Edit – seems ok in the body of a post

                #839334
                Michael Gilligan
                Participant
                  @michaelgilligan61133

                  Nice try, Rob

                  MichaelG.

                  #839337
                  Robert Atkinson 2
                  Participant
                    @robertatkinson2

                    Ahh an inclined manometer. Used to measure low pressure differentials. Many used special low density fluids often kerosine based.

                    Robert.

                    #839338
                    Michael Gilligan
                    Participant
                      @michaelgilligan61133

                      Thanks, Robert … I just need to find the instructions now

                      MichaelG

                      #839353
                      Michael Gilligan
                      Participant
                        @michaelgilligan61133

                        I soaked the label off the bottle, and have the text [with only the single most important word being illegible ! ]

                        Maybe tomorrow, in daylight

                        .

                        IMG_0389

                        .

                        MichaelG.

                        #839354
                        Michael Gilligan
                        Participant
                          @michaelgilligan61133

                          … Which led me to this:

                          https://www.ebay.co.uk/itm/196750926471

                          … with lots of nice pictures and a fairly good description.

                          MichaelG.

                          #839359
                          Wingo
                          Participant
                            @wingo

                            I think it’s a DP gauge normally used to check filter banks in building heating and venting systems.

                            High DP means time to change the filter. Some ‘roll’ type filters used a HP to trigger a motor to wind the filter onto a new section.

                            Michael

                            #839362
                            peak4
                            Participant
                              @peak4

                              There’s also a later one, but again without paperwork “Differential Manometer” might be a helpful search term, though I didn’t immediately spot anything obvious on how to use it, or what should be in the tube.
                              https://www.ebay.co.uk/itm/155631714555

                              Bill

                              #839365
                              Robert Atkinson 2
                              Participant
                                @robertatkinson2
                                #839366
                                peak4
                                Participant
                                  @peak4

                                  Page 95 of this one is getting close, suggesting yours is a little after the date of this catalogue
                                  https://www.analogweather.com/uploads/7/7/7/5/77750690/casella_-_meteorological_and_scientific_instrument_catalog_684_-_1948.pdf

                                  This was the main download page
                                  https://www.analogweather.com/-casella.html

                                  image_2026-02-25_223329195

                                  #839370
                                  Grindstone Cowboy
                                  Participant
                                    @grindstonecowboy
                                    On Michael Gilligan Said:

                                    I soaked the label off the bottle, and have the text [with only the single most important word being illegible ! ]

                                    .

                                    MichaelG.

                                    That says “FLUID”

                                    Rob

                                    #839380
                                    Michael Gilligan
                                    Participant
                                      @michaelgilligan61133

                                      Well done, Rob !

                                      I’ve just woken-up, realising that it was the only word that could reasonably fit.

                                      … a cruel joke by Casella, methinks !

                                      MichaelG.

                                      .

                                      Edit: from Bill’s reference, the bottle likely contained something from the photographic industry, or plain water with a drop of Fairy Liquid.

                                       

                                      #839383
                                      Alan Charleston
                                      Participant
                                        @alancharleston78882

                                        Hi Michael,

                                        It’s an incline manometer. I used to use one to measure the pressure drop across a pitot tube when measuring the gas velocities during stack testing. It’s inclined because the pressures are small and the incline expands the scale so it’s easier to read.

                                        The liquid had a density of I think 0.86 which also lengthened the scale. The density needs to be correct for the scale reading to be accurate. When the first digital manometers first came out they were very expensive but I was keen to get one. I guess that tells you what I thought of the incline manometers.

                                        Regards,

                                        Alan C.

                                        #839402
                                        Michael Gilligan
                                        Participant
                                          @michaelgilligan61133

                                          Thanks Alan … Yes, I understand the logic of the incline, but as you observe, knowing the density of the fluid would be critical if the measurements are to be meaningful.

                                          … or is it just used as a comparator ??

                                          MichaelG.

                                          #839425
                                          Robert Atkinson 2
                                          Participant
                                            @robertatkinson2

                                            The Manometer is an accurate differential pressure gauge but accuracy depends on the density of the fluid. We used to change the fluid in the ones in an aircraft instrument shop every year. Density can change due to evaporation of volatile components. Inclined manometers normally use low density fluids. Why increase sensitivity by inclining and then reduce it with a high density fluid? High or low is relative to water (1).

                                            The manometer can be calibrated directly in pressur (inches of water, PSI, millibar, whatever)  or if intended for velocity measurement or similar it may have custom calibration for a specific transducer like a pitot-static probe, venturi etc.

                                            Robert.

                                            #839427
                                            Michael Gilligan
                                            Participant
                                              @michaelgilligan61133

                                              My point, Robert was that Bill’s quote explicitly references water with the addition of a wetting agent … whereas Alan recalls using a liquid with a density of about 0.86

                                              This innocent will remain bewildered until he reads the instruction manual for the instrument.

                                              MichaelG.

                                              #839501
                                              Robert Atkinson 2
                                              Participant
                                                @robertatkinson2

                                                It is unlikey that the unit was supplied with a bottle of “fluid” if it was intended for use with water.

                                                A manual almost https://ehive.com/collections/6274/objects/633426/instruction-leaflet-of-draught-guage

                                                Info but paywalled Journal of Scientific Instruments, Volume 29, Number 2

                                                Robert.

                                                #839502
                                                duncan webster 1
                                                Participant
                                                  @duncanwebster1

                                                  If we knew the angle of the tube from horizontal, the distance between the markings, and what units they represent, the required fluid density would be fairly easy to calculate.

                                                  As the angle to horizontal is important I’m surprised it doesn’t have a bubble level incorporated.

                                                  #839503
                                                  Michael Gilligan
                                                  Participant
                                                    @michaelgilligan61133

                                                    Thanks, Robert … I now have the paywalled item, courtesy of “institutional access”

                                                    [which regrettably means I am not permitted to distribute it]

                                                    Suffice it to say that yes …

                                                    The indicating medium is a special clear, non-staining, mobile liquid of specific gravity less than unity […]

                                                    Sounds to me like Casella was selling ‘Snake Oil’

                                                    MichaelG.

                                                    .

                                                    Edit: … The article is however also available here:

                                                    https://iopscience.iop.org/article/10.1088/0950-7671/29/2/415/pdf

                                                    No paywall, no need for me to worry about sharing 🙂

                                                    #839504
                                                    Michael Gilligan
                                                    Participant
                                                      @michaelgilligan61133
                                                      On duncan webster 1 Said:

                                                      […]

                                                      As the angle to horizontal is important I’m surprised it doesn’t have a bubble level incorporated.

                                                      It does

                                                      Michael G

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