wg48temp9
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100mm differential pressure guage
On eBay i won a 100mm differential Bourdon pressure gauge 0-50 in Wg. about one division is equal 1 torr. I think I could read it to about 1/4 of a
division, that's 0.25 torr.
I screwed up. To use it to measure even 50 torr (absolute pressure), I would have to put a good vacuum on one input and the vacuum to be measured on
the other input. I think I will have to be careful not to expose it to a differential of atmospheric pressure as that will be about 8x greater than
its full scale reading which I assume will damage it i.e. bend the pointer on the stop or permanently bend the Bourdon tube. I will need a valve on
each input to isolate the gauge and one valve to connect both input together when I release the vacuums.
Could the Bourdon tube have hard stops just outside of full range ???
Below is a pic of the gauge. The second pic of an odd looking lever with a + sign on the side at the top of the gauge. Anyone know what it is or does
???.
[Edited on 10/8/2024 by wg48temp9]
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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Rainwater
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It lets you take the gauge apart, replace the glass, adjust zero, routine maintenance, and cleaning.
Differential guauge is not very good at taking measurements relative to the atmosphere. You may have the wrong tool for the job.
anytime you deal with a differential guage, you need a manifold with isolation and bypass.
"You can't do that" - challenge accepted
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Sulaiman
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I have an old Magnehelic differential gauge that was working before I killed it.
(a tool from the 70's for diagnosing and setting up positive or negative pressures or pressure drops across air filters for 200 IPS tape drives)
When working I could suck one side or blow the other with atmospheric pressure in the unused side.
My gauge displayed pressure difference of 0 to 100 inches of water
with max pressure 15 psig.
Why is a manifold and bypass required?
,...................
IF you ever have the gauge handy when setting up a fractional distillation rig with a packed column,
you could consider setting up the gauge between the top and the bottom of the column.
I've read that maintaining a constant pressure differential implies a constant vapour speed,
which helps with fine fractionation.
If the gauge is useful or valuable to you then filters/vapour traps would be required - probably not worth the effort.
CAUTION : Hobby Chemist, not Professional or even Amateur
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wg48temp9
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Below is a corrected post I was unable to post:
On eBay i won a 100mm differential Bourdon pressure gauge 0-30 in Wg. about one division is equal to 1.87 torr. I think I could read it to about 1/4
of a division, that's 0.618 torr.
I screwed up. To use it to measure a vacuum of a few torr (absolute pressure), I would have to put a good vacuum on one input and the vacuum to be
measured on the other input. I think I will have to be careful not to expose it to a differential of atmospheric pressure as that will be about 13.3x
greater than its full scale reading which I assume will damage it i.e. bend the pointer on the stop or permanently bend the Bourdon tube. I will need
a valve on each input to isolate the gauge and one valve to connect both input together when I release the vacuums.
Could the Bourdon tube have hard stops just outside of full range ???
Below is a pic of the gauge. The second pic of an odd looking lever with a + sign on the side at the top of the gauge. Anyone know what it is or does
???.
[file]103211[/file]
[file]103213[/file]
[Edited on 10/8/2024 by wg48temp9] corrected my maths
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
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wg48temp9
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Posts: 783
Registered: 30-12-2018
Location: not so United Kingdom
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Quote: Originally posted by Sulaiman  | I have an old Magnehelic differential gauge that was working before I killed it.
(a tool from the 70's for diagnosing and setting up positive or negative pressures or pressure drops across air filters for 200 IPS tape drives)
When working I could suck one side or blow the other with atmospheric pressure in the unused side.
My gauge displayed pressure difference of 0 to 100 inches of water
with max pressure 15 psig.
Why is a manifold and bypass required?
,...................
. |
So I assume your meaning was your gauge could withstand a diff pressure of one atmosphere. That's about 4x full scale. In the case of my gauge, its
13.3x full scale. Perhaps it can survive it.
Did you kill your gauge with over pressure, then what was that pressure?
I assumed rainwater meaning of manifold is a set of valves similar to the manifolds used in gassing refrigerants into air conditioning units.
As I described in my original post, its required to prevent a diff pressure of one atmosphere.
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
|
|
|
Rainwater
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https://www.bourdon-instruments.com/us/en/product-overview/d...
Manual for a close match to your gauge. Being graduated in wg is the only difference I see. Might be an older model.
image taken from the linked manual
Normally this type of instrument requires servicing without shutting down the process chain being monitored.
Part of routine service is verification of operation.
Supose the gauge reads a clear 10wg.
You then simultaneously close both isolation valves.
You should not observe any change in the reading.
Now you open the bypass valve, you should observe a reading of 0zero.
Non routine procedures may require isolating the valve to prevent damage.
Process such as backflow/back washing will cause a reverse polarity.
And then sometimes you just need to approach absolute rated maximum to clear out the goop
[Edited on 10-10-2024 by Rainwater]
"You can't do that" - challenge accepted
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Sulaiman
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I dropped it 
Pressure gauges and thermometers seem to have suicidal tendencies when in my care.
I have more than enough collected treasure to repair.
(Although during my last house move the removal guys labeled the boxes for most of my treasure as "shed, junk"
I was upset but my family found it funny (/true) ! )
CAUTION : Hobby Chemist, not Professional or even Amateur
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wg48temp9
National Hazard
Posts: 783
Registered: 30-12-2018
Location: not so United Kingdom
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Apparently my glassware has these suicidal tendencies too, and I thought it was my clumsiness, LOL.
I am wg48 but not on my usual pc hence the temp handle.
Thank goodness for Fleming and the fungi.
Old codger' lives matters, wear a mask and help save them.
Be aware of demagoguery, keep your frontal lobes fully engaged.
I don't know who invented mRNA vaccines but they should get a fancy medal and I hope they made a shed load of money from it.
|
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|
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