tank pressure sensor any electronic engineers on here ?

simonfraser

simonfraser

Well-Known Member
Joined
13 Mar 2004
Messages
7,609
Location
Outboards 4 mobo’s, unless you do a lot of miles
Visit site
i have used one of these
https://uk.farnell.com/honeywell/hscsaan001pdaa5/sensor-1psi-dual-axial-sip-5v/dp/1823226
which is then connected to a 'converter' that changes the voltage into resistance
a VDO analogue is connected to this to show the water level, bit of a bodge job !
the VDO needs 0-180 ohms, empty to full

i have no access to the tank top, possible to the sides, just, but sticking something to the side would be very challenging due to restricted access

the honeywell sensor has done the job, but is only designed for dry gasses
as the sensor needs to be below the tank level some water seeps to the sensor and then it fails

any way i can set up a waterproof sensor below the tank level, i have a spare water feed for this
5V and 12V on tap
which then feeds the resistance straight back to the VDO ?
some calibration required of course, the water level in the tank is around 45cm

ok with a soldering iron, so could put something together with guidance

tnx
 
simonfraser said:
i have used one of these
https://uk.farnell.com/honeywell/hscsaan001pdaa5/sensor-1psi-dual-axial-sip-5v/dp/1823226
which is then connected to a 'converter' that changes the voltage into resistance
a VDO analogue is connected to this to show the water level, bit of a bodge job !
the VDO needs 0-180 ohms, empty to full

i have no access to the tank top, possible to the sides, just, but sticking something to the side would be very challenging due to restricted access

the honeywell sensor has done the job, but is only designed for dry gasses
as the sensor needs to be below the tank level some water seeps to the sensor and then it fails

any way i can set up a waterproof sensor below the tank level, i have a spare water feed for this
5V and 12V on tap
which then feeds the resistance straight back to the VDO ?
some calibration required of course, the water level in the tank is around 45cm

ok with a soldering iron, so could put something together with guidance

tnx
Click to expand...
Why not put that sensor above tank level & connect it with a tube to the tank ?

It works on air pressure & does not need to be wet.

I have a similar problem on a boat, vdo 4-20ma probe sensor has died on a fresh water tank.

New sensor, stupidly expensive. Looking for options to replace.

So intrigued by your voltage to resistance converter
 
+ 1 on what starfire says

using a pressure sensor for the water tank and about to install the second one on diesel tank. Works fine compressing air, doesn't have to get the liquid there - just make sure the pipe is sound and not split.

regarding the voltage to resistance conversion, I went another route and converted the voltage to NMEA2000 signal and then to any N2K display. But I didn't have a gauge already...

I'm using http://www.farnell.com/datasheets/2097509.pdf or the 0-50kPa equivalent.
they are good for higher tanks (1m approx, OP is only up to .6m or so) and they are half the price of the one you mention

V.
 
starfire said:
Why not put that sensor above tank level & connect it with a tube to the tank ?

It works on air pressure & does not need to be wet.

I have a similar problem on a boat, vdo 4-20ma probe sensor has died on a fresh water tank.

New sensor, stupidly expensive. Looking for options to replace.

So intrigued by your voltage to resistance converter
Click to expand...

indeed, can't find the instructions for the converter :(
hopefully it has something useful on the box when i fish it out from behind the dashboard

doh, fit it above the tank :)

MPX5010D looks like the one i fitted a year or so ago
will order that, pin style 1 i recon ?
 
Last edited:
I'd order unibody packages, easier to solder and shrink wrap each solder joint ;)
MPX5010DP CASE 867C-05
or if you are going to fit on a PCB, just get the through hole ones I guess.

V.
 
sf,

I'm not an el. engineer (although I do play one at home/boat), but I do have a work colleague who is and helps with links/wiring diagrams (then I do the programming and swearing sessions myself...)
I'll ask him about 0-180Ω gauges as I'm about to setup a trim tabs sender for a mate from Bennet trim tab coil senders.
Easy things you can do without a board, not sure about turning volt to Ohms though...

V.
 
simon,

are you the one that bought the remaining stock of these MPX5010DP CASE 867C-05 pressure sensors from Farnell? noticed they are out of stock on my shopping basket now :D
no worries I'll get some others, just wondering...
usually takes me a week to put together all the bits I want for an order and often things run out of stock in the meantime

V.
 
starfire said:
Why not put that sensor above tank level & connect it with a tube to the tank ?

It works on air pressure & does not need to be wet.

I have a similar problem on a boat, vdo 4-20ma probe sensor has died on a fresh water tank.

New sensor, stupidly expensive. Looking for options to replace.

So intrigued by your voltage to resistance converter
Click to expand...

This is a 4 to 20mA to voltage converter

HW-685 0/4-20mA to 0-3.3/5/10V Voltage Transmitter Signal Converter Module

This also gives you a circuit

Converting a 4 to 20 mA signal to 0 to 5V

Similar devices can b obtained from RS or from China via E-Bay.

VDO do have gauges that will receive 4 to 20mA signals. I usd one for my diesel tank levels as I have a 4 - 20 mA sensor like you but not VDO.

One think to consider that its the sender that has the resistance range the gauge reads the voltage that is tapped off the variable resistor (potentiometer) of the sender. The gauge is det up to react to the voltage depending on the potentiometer range direction (high to low) or (low to high) US or EU
 
Last edited by a moderator:
Rogershaw,

unless I got it completely wrong, starfire is after the exact opposite, voltage to 4-20mA converter (in order to feed the gauge)

starfire:
not sure what sensor you're after, but I managed to source (via ebay of course) a few GEM (iirc that's the brand name) decent quality senders for v.reasonable costs, 2X40bar for gbox oil pressure and a 20bar for stabilisers oil pressure.
Don't go for Danfoss and other such known names!

V.
 
Rogershaw said:
This is a 4 to 20mA to voltage converter

HW-685 0/4-20mA to 0-3.3/5/10V Voltage Transmitter Signal Converter Module

This also gives you a circuit

Converting a 4 to 20 mA signal to 0 to 5V

Similar devices can b obtained from RS or from China via E-Bay.

VDO do have gauges that will receive 4 to 20mA signals. I usd one for my diesel tank levels as I have a 4 - 20 mA sensor like you but not VDO.

One think to consider that its the sender that has the resistance range the gauge reads the voltage that is tapped off the variable resistor (potentiometer) of the sender. The gauge is det up to react to the voltage depending on the potentiometer range direction (high to low) or (low to high) US or EU
Click to expand...

I have the opposite problem, a 4-20mA sender has died, feeding a vdo gauge that's part of a matching dash install.

So I need to convert & scale the output of a pressure sensor to 4-20ma, ideally with the converter supply fed from the 4-20ma loop (2 wires)

When I emerge from apathy, I'll think some more about it.

Vas. Quite correct, but this is to replace a stupidly expensive tank level sender.
 
starfire said:
Why not put that sensor above tank level & connect it with a tube to the tank ?

It works on air pressure & does not need to be wet.

I have a similar problem on a boat, vdo 4-20ma probe sensor has died on a fresh water tank.

New sensor, stupidly expensive. Looking for options to replace.

So intrigued by your voltage to resistance converter
Click to expand...

I would be grateful for an explanation of how a “non wet” transducer works.
This is what it seems to me:

Let’s have a tank, a vertical thin hose from tank bottom to a transducer placed at 2 metre above the hose/tank connection.
Tank practically empty. Water level same in both tank and hose, just above the hose/tank connection.
Absolute pressure at level both in tank and in hose air = about 1 bar

Let’s fill the tank with water to 1 metre higher than connection. Absolute pressure in the tank at connection level = about 1.1 bar
Absolute pressure in hose air = 1.1 bar. Air pressure increased by 10%, air volume is reduced by 10%, thus level in hose will raise above connection by 10% of hose lenght = 0.2 metres.

0.2 metre of water make for 0.02 bar, thus, the absolute pressure in tank at connection level being 1.1 bar, the air in hose - and transducer - pressure will be = 1.1-0.02 = 1.08 bar, that is a measuring error of 0.02 bar or of 0.2 metre level.

As such an accuracy is not accectable, there must be something I am missing in the above or the real application is more complex.

Please clarify for me if you have got the time (of which unfortunately I am afraid you have plenty theese days)

Tank you, cheers

Sandro
 
Sandro said:
Let’s fill the tank with water to 1 metre higher than connection. Absolute pressure in the tank at connection level = about 1.1 bar
Absolute pressure in hose air = 1.1 bar. Air pressure increased by 10%, air volume is reduced by 10%, thus level in hose will raise above connection by 10% of hose lenght = 0.2 metres.
Click to expand...
air volume not reduced by 10%, water in hose stays put at 0 point, pressure "passes" on to sensor securely sealed on top of hose, job done.

tried it at home with sensor hose and a 1.5lt bottle of water, as soon as I started pushing the (empty) hose on the full bottle sensor got the pressure just right.

cheers

V.
 
To compress the air in the tube, the liquid needs to rise up the tube. If you solve the simultaneous equations for the pressure at the bottom of the tube, hopefully the pressure in the tube [measured by the sensor] will look a bit like the numbers in the attachment.
 

Attachments

starfire said:
Why not put that sensor above tank level & connect it with a tube to the tank ?

It works on air pressure & does not need to be wet.
Click to expand...

The pressure on the sensor is driven by the height of the column of liquid above it ... in theory, putting it above and making certain there is only air in the pipe is fine .. but over time, fluid will enter the pipe and the pressure will drop, and the level readings will become close to zero, even when the tank is full ...
 
rszemeti said:
The pressure on the sensor is driven by the height of the column of liquid above it ... in theory, putting it above and making certain there is only air in the pipe is fine .. but over time, fluid will enter the pipe and the pressure will drop, and the level readings will become close to zero, even when the tank is full ...
Click to expand...
I think that's only going to happen if there's a leak in the pipe/sensor assembly which would be a problem anyway in the normal setup, so no difference there.

V.
 
You must log in or register to reply here.

Share this page

Top