Hello,
Is it possible to use a differential pressure sensor DVLR -L60D whose range is 2 psi to -2 psi for measuring vacuum pressures ?
Thank you
Yes, down to -2 psi.
You can get absolute pressure transducers good down to 0 bar absolute.
jremington:
Yes, down to -2 psi.
I have always gotten a kick of - pressure.
the absence of pressure is no pressure.
I understand that we have an unspoken agreement that it is minus the atmospheric pressure where the higher side is being read.
as a note to the OP, atmospheric pressure is generally considered 14.7 PSI. so, you can read from atmospheric pressure to the complete absence of pressure, or zero pressure , or a delta P of 14.7 psi relative to atmospheric.
the sensor in question may be able to read delta P of 2 psi.
There is no confusion about the meaning of -2 psi, when using a differential pressure sensor.
Well... The OP may have some confusion.
Not with the differential pressure sensor mentioned in the first post.
You can use an absolute pressure sensor for 100-150 mm Hg.
Here is a selection of "vacuum gauges"
Wont it show the difference between the 2 ports so that I can get my vacuum pressure reading?
No, because the absolute pressure 100 mm Hg is outside of the differential range you stated (+2 to -2 psi) with respect to atmospheric pressure.
You are confused and need to study how pressure and vacuum is measured.
jremington:
There is no confusion about the meaning of -2 psi, when using a differential pressure sensor.
really ?
there can be 2 psi delta
but both values are above 0
you cannot have a pressure less than zero, so negative pressures are unattainable.
there is only a higher pressure
In HVAC, where engineering is a rather casual affair, there are lots of uses of words that are convenient, but not technically accurate.
there is no question you can have a pressure that is negative to a reference, but both are above zero.
and slang does allow for one overlooking the correct terminology.
I would agree that people would instantly know what you mean.
but, who knows, maybe one day they will make a resistor that is -120 ohms ?
Thanks for that, but I'm not at all confused by differential pressure sensors or the fact that some at times indicate negative pressure readings.
Others evidently are confused, including the OP.
The OP posted a differential pressure sensor with a high and a low port.
Since the sensor has no concern about what ports are connected to what, it would seem that one could leave one port open and the differential pressure would be output from the device.
jremington:
Thanks for that, but I'm not at all confused by differential pressure sensors or the fact that some at times indicate negative pressure readings.Others evidently are confused, including the OP.
my point is that if we use fictitious terms that have no scientific meaning we are adding to the confusion.
as a note, almost all of the words in the dictionary were created by those with either the very highest language skills, or with the very lowest, the vast majority by those with almost no command of the language. even the writers of the dictionary admit that those with the poorest language skills control the meanings of words by using them incorrectly over time to the point that they become accepted.
Take a few minutes, draw some lines/boxes/bubbles, plot a chart. figure out how to obtain a negative pressure.
a simple X/Y graph with 0 at the base and in 5 minutes, there is no confusion.
dpoornima:
Hello,Thank you for the information.
I wanted to read pressures around 100-150 mm Hg which is roughly around 2 psi. So if I leave one port to the atmosphere and the other to the vacuum, I should be able to read the pressure right.
Absolute pressure or differential (gauge, if referred to atmosphere)?
100mmHg absolute? No. 100-150mmHg differential? Maybe. 150mmHg is a bit more than 2psi.