Vacuum gauge with MD-PS002

[AjaxOfTheRockies]

I just started working on a multi-line vacuum gauge I'd like to build around Arduino and would appreciate any input the more learned here might have as I begin.

Today the sensors arrived - MD-PS002,  to which I've read some threads about its interface with Arduino.  I learned, also today, that I will need to incorporate the HX711 A/D converter-amplifier and have located a source for them

The one I found says it's two channel, so I was wondering if I need two of them to get four vacuum readings, or one for each vacuum sensor.  Anyone?  

Here's what I'm going for:
My device is going to monitor four vacuum lines which will pull in the neighborhood of 12" Hg.  I don't need a precise measurement, just relative.  My goal is to produce four bars on an OLED display.   I need to adjust the four vacuum sources so that they match closely, but they don't have to be perfect.  And, again, I don't care what the actual vacuum measurement is, just that they're all equal.

I have found some sample code to start with, but would also appreciate any tips on how to approach this challenge.

Thanks!

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[jremington]

Please post a link to the data sheet.

[AjaxOfTheRockies]

https://components101.com/ics/hx711-24-bit-analog-digital-converter-adc

It looks like I need two of these to interface four of the MD-PS002 vacuum sensors

[AjaxOfTheRockies]

Not a lot of info on the sensor itself

http://www.datasheetbank.com/datasheet-download/880658/1/ETC1/MD-PS002

[jremington]

Why do you think that sensor is usable as a vacuum gauge?

Why buy an essentially undocumented sensor?

[MarkT]

The pressure range is 15psi--100psi, if I'm reading it right - not a vacuum sensor at all??
But the information is pretty unclear.

[Paul_KD7HB]

A vacuum gauge will show the current air pressure when it is not connected to anything. Do your gauges show that or do they show zero?

Paul

[AjaxOfTheRockies]

Why do you think that sensor is usable as a vacuum gauge?

Why buy an essentially undocumented sensor?

It was advertised as such when I purchased it. 
"Comimark 2Pcs Sensore pressione MD-PS002 Vacuum Sensor Absolute Pressure Senso for Arduino"

Also, read another thread using the same part in a vacuum device controller.   Seemed legit.
https://forum.arduino.cc/index.php?topic=205595.15

This begins "I use HX711 with my PS002 vacuum sensor and have no problem."

I read at length and came to understand that 'absolute' pressure uses readings which begin at zero - vacuum - and proceed in fractional units of a Pascal.  The specs on the MD-PS002 state:   "150kpa (absolute pressure) Pressure range from vacuum (absolute 0 pressure) above atmospheric pressure 50kpa"

So, yeah.  I assumed it would sense vacuum.

And it's not much less documented than a lot of the specialized components you can find.  I was counting on someone else has used this thing and might offer some helpful input.

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[AjaxOfTheRockies]

The pressure range is 15psi--100psi, if I'm reading it right - not a vacuum sensor at all??
But the information is pretty unclear.

Hi Mark,
 The spec on the product says the range is "from vacuum (absolute 0 pressure) above atmospheric pressure 50kpa.  Yeah, documentation a bit sparse, though I'm still optimistic someone has some knowledge to share.
Thanks.
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[AjaxOfTheRockies]

The pressure range is 15psi--100psi, if I'm reading it right - not a vacuum sensor at all??
But the information is pretty unclea

A vacuum gauge will show the current air pressure when it is not connected to anything. Do your gauges show that or do they show zero?

Paul

Hi Paul,
 I don't have anything working just yet.  I am collecting parts and building as I go, so no gauge info to report on at this time.

If you or anyone have a suggestion on a sensor to employ in this project, I am open to hearing.  The MD-PS002 are very cheap, so if I don't end up using them, the bank won't complain.

Thanks!

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