What did I buy ?

[Alan CharlestonParticipant @alancharleston78882]

Hi Michael,

I could be wrong about the density being 0.86. It’s been about 30 years since I last used an incline manometer. This link may be useful:

https://www.dwyeromega.com/en-us/durable-gage-fluids-red-0-826-sp-gr-blue-1-91-sp-gr-green-concentrate/p/Gage-Fluids

I used to use a Dwyer instrument with the red oil which has a density of 0.826. It had a foul smell – can you detect an odour from your bottle?

In any case, I assume your manometer is calibrated in inches water gauge so if you level it and measure the slope, you should be able to work out what the fluid density should be. You can then source some of it from Dwyers. Seems to be relatively cheap.

Regards,

Alan C.

[Michael Gilligan]

On Michael Gilligan Said:

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.

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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 🙂

Still paywalled for me. Maybe it’s set a cookie for your institution on your computer.

Robert.

[Robert Atkinson 2]

On Robert Atkinson 2 Said:

Still paywalled for me. Maybe it’s set a cookie for your institution on your computer.

.

Apologies for that, Robert …

It seems you are correct

[Alan Charleston]

On Alan Charleston Said:

Hi Michael,

I could be wrong about the density being 0.86. It’s been about 30 years since I last used an incline manometer. This link may be useful: […]

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Thanks for the very helpful additional comments, Alan
… You have set me on the right path.

My bottle was so shrivelled that it reminded me of ‘Pete Marsh’ … but I soaked in water and it recovered some shape and flexibility 🙂

I will post some photos later, but the bad news is that the bottle was both empty, and split … so I doubt that any forensic evidence remains.

MichaelG.

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Ref: https://www.britishmuseum.org/collection/object/H_1984-1002-2

[Michael GilliganParticipant @michaelgilligan61133]

As promised:

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MichaelG.

[Alan CharlestonParticipant @alancharleston78882]

Hi Michael,

The manometer has a reservoir that contains the liquid. This is filled until it is roughly the right level and there is probably a system for making minor adjustments to the level for zero adjustments. The reservoir is sealed and is pressurised by the signal.

If you get to the stage of wanting to check it, you will need a low pressure source (1 – 4 inches water gauge). An ordinary air regulator isn’t any good as 1 inch WG is only 0.036psi. I have attached a diagram showing a setup which will supply the low pressure required.

High pressure air is supplied via an ON/OFF valve to a throttling valve/ The bottom of the Tee is submerged in water to the required depth (say 1″”). The outlet to the manometer is plugged and the ON/OFF valve is opened. The throttling valve (which should be a small ball valve) is then cracked open such that a bubble is expelled from the bottom of the Tee every 5 – 10 seconds. The orifice should be kept fairly small (1/8″ – 3/16″) as the pressure will rise and fall as  a bubble grows and then detaches. The bigger the bubble, the greater the pressure variation.

The outlet can then be connected to the manometer. Don’t try setting the air flow rate while connected to the manometer. If the throttling valve is opened too far the manometer will be subjected to a high pressure which is likely to empty the reservoir out the end of the manometer tube.

The manometer reading will rise and fall slightly as the bubbles form and detach. Take the low reading which will correlate to the depth of the end of the Tee.

Hope this is useful.

Regards,

Alan C.

[Michael GilliganParticipant @michaelgilligan61133]

VERY useful, Alan … and duly noted for future reference

Thank You

MichaelG.

[Robert Atkinson 2Participant @robertatkinson2]

Fine zero adjustment is acheived by moving the scale not adjusting the angle. There is a pin at the lower end of the scale to facilitate this. The manometer should be kept level when in use. The foot at the lower end is rotated 90 degrees to stop it tipping.
The caps on the ports keep the fluid in the level when not in use.

There is a later one on ebay at the omoment but pictures are poor. https://www.ebay.co.uk/itm/155631714555

Robert

[Author]

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