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I was just wondering because in almost all of the vessels I saw, the two always go together.
Thanks.
Walt Boyes
Editor in Chief
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If it's a critical application it might have more than one transmitter or the level transmitter might be backed up with High or Low level switch.
Level gauges are usually only used on clean liquids or where the tank is not agitated.
Roy
Thanks!
I need help. I am confused about how you determined the correlation between the P=F/A with the level of liquid in open tank since I know the increasing of liquid level on area will cause the pressure at datum line of the transmitter HP connection to increase also (Differential Pressure Transmitter). (Yes I know the result will be Kpa.) Why if I calculated it with another equation P=specific gravity*gravity*height of the tank, the result will be different? Can someone explain that?
P = SG * Height
A simple way is to calculate the pressure of a column of water then multiply by SG.
Roy
I don't understand well your question but here is the following:
Hydrostatic pressure (pressure created by a liquid or column liquid) is:
Pressure of liquid = Height * Sg (specific gravity)
You can do a relation from this P = F/A using the unit converter factors because 1 Psig = 27.7"H2O. Then if you have your level value in Psig or something like that, you must be making the following in order to get the real level.
For example if you have two psig in a gauge installed in the bottom of an open tank and the liquid inside the tank is only water, this two psig represents a level of about 56 "H2O because 2 x 27.7"H2O = 56"H2O, but if you have the same value (2 psig) with a liquid of SG = 0.65 then:
P = h * sg -------> h = P/sg -------> h = 56"H2O / 0.65 = 86" of that
liquid (0.65)
A liquid with specific gravity of 0.65 will need more height to create two psig of pressure.
If you have only water, it will need about 56" of height to create two psig of pressure.
I hope I helped you with this.
Regards,
Juan
We have learned during our study that the Pressure, P (which is independent of cross section area of tank) at the bottom of the tank:
P = ROW * G * h
Where
ROW = Density of liquid
G = Gravitational constant
H = height of the liquid in tank
As per your formula, what is the effect of Gravitational Constant?
I think Juan Pinzon summed it up in his response.
Regards
Roy
you're right roy, I have just try using dp transmitter and the result when I measured the level are close to the equation of juan given thank you for your enlightment.
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