Paul,

I started working with the Arduino board and got a GM temp sensor to
print out the temp.  I also found some code for using a VDO sender
360-009 for oil pressure 0 to 80psi.  Can these sensors work on other
engine fluids such as water and fuel? It would be nice to have oil,
waterand fuel pressures and oil and water temps.  I also found an app
that when downloaded into an apple device provides a way to display
data.  I just need a wifiy shield for the aduino and now we can monitor
the engine and move around to make adjustments.  Thanks for any help

Joe Berki
LimoEz






The problem with using one sensor for oil, water and fuel pressure
becomes one of scaling. The sensor is good to 80 psi. It will not be
damaged by an over pressure of some amount of say 20 psi which is 100
psi. The problem is it will not output the pressure value in the
scaling. It quits at 80 psi. Anything more is over limit. The sensor
does not send out an over limit reading.
Now fuel pressure for EFI goes to 45 - 50 PSI. A bit over 1/2 of the
sensors range. Water pressure will be maxed out at the cap pressure; 15
- 30 lbs.
With process controls, the output of a pressure transmitter is scaled 0
- 25,000 give or take a bit. So if the 0 - 80 psi sensor is used in all
three locations, the EFI pressure is just over 1/2 the sensor span and
the water pressure is about 1/3 span. The readout accuracy is not there.
For EFI systems the sensors give the board response back as 1-5 volts.
If you spit the fuel pressure range to 48 PSI span which is 60% of the
sensor span, you will only get a max of about 3 volts back. For the
water pressure, 5/3 is less than 2 volts. To make it work properly, you
would have to scale the outputs to show the 80 PSI as the span of what
you are sensing. What is lost is the sensitivity that a 0.05 volt change
give in the reading.
Now you can scale at what ever you want, but it is easier to use one
scale for 0-5 volts and use the proper sensor for the expected span.
Dale Davies



Thanks Dale,

From your comments it would be appropriate to use 0-80psi sensor for
oil, 0-50psi for fuel, 0-20psi for water?  Water and oil temp seem close
enough to use the same sensor (SU 109).  My concern was the reaction of
the materials used to make the sensor to the fluid that is measured.

Thanks

Joe Berki

-
The metalurgy of the sensors should not be a problem for oil, fuel, and
coolant. We have some nasty chemicals and components related to the oil
patch. Had one well that had water, sour oil and gas. The H2S combines
with the water to form sulphur acid. Battery acid is more corrosive than
96% pure sulphur acid. The sour water would destroy the valve housing in
one month. Naturally the company did not like the cost of the housing
for that application. Nothing that nasty in the engine fluids.

Dale Davies