Electric Vacuum Sensor/Gauge

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neil1967

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I have a pneumatic vacuum gauge fitted to my fuel system to indicate if my fuel filter is getting blocked. However, the gauge is located close to the filter, which is inconvenient. Ideally I would like to fit the gauge in the instrument panel, but this would involve about 3m of fuel line. Ideally I'd like to fit an electric pressure sensor and gauge, but I have been unable to find one. Any ideas, or should I just run a 3m fuel line to the panel?
 
Vehicle MAP sensor?
MAP is 'manifold absolute pressure'.
Some of these have simple voltage outputs which might drive a digital voltmeter.

I looked into this for balancing motorbike carbs about 15 years ago, so more research might be needed!
Could be a nice Arduino or Rasb.Pi project for those inclined?
ISTR Honeywell make a lot of the sensors?
 
neil1967 said:
I have a pneumatic vacuum gauge fitted to my fuel system to indicate if my fuel filter is getting blocked. However, the gauge is located close to the filter, which is inconvenient. Ideally I would like to fit the gauge in the instrument panel, but this would involve about 3m of fuel line. Ideally I'd like to fit an electric pressure sensor and gauge, but I have been unable to find one. Any ideas, or should I just run a 3m fuel line to the panel?
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There's no problem running a fuel line that far, or even further. I had a vacuum gauge on my last boat, with at least 3m of pipe between it and the filter.
 
neil1967 said:
I have a pneumatic vacuum gauge fitted to my fuel system to indicate if my fuel filter is getting blocked. However, the gauge is located close to the filter, which is inconvenient. Ideally I would like to fit the gauge in the instrument panel, but this would involve about 3m of fuel line. Ideally I'd like to fit an electric pressure sensor and gauge, but I have been unable to find one. Any ideas, or should I just run a 3m fuel line to the panel?
Click to expand...
Running a little hose to the panel is not that much different from running a cable the same way and the whole setup is much simpler and reliable than electric gauge.
 
My (intended!) solution is to route it through the bulkhead separating the head from the engine compartment. If I mount it close to the head door it will be quite convenient when on passage and entering a line in the log, to crane my neck, observe the vacuum reading and log that also.
 
i ran a hard walled tube from car engine inlet manifold to inside car with gauge when figuring out misfiring/turbos etc. i ended up leaving it for a few years. no problems/leaks etc (although air not diesel!)
 
bikedaft said:
i ran a hard walled tube from car engine inlet manifold to inside car with gauge when figuring out misfiring/turbos etc. i ended up leaving it for a few years. no problems/leaks etc (although air not diesel!)
Click to expand...

It's nearly all air in the pipe to a remote vacuum gauge.
 
Rogershaw said:
Breakout Board MPXV7002DP transducer APM2.5 APM2.52 Differential Pressure sensor | eBay
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That's an interesting device, but I doubt it has the pressure range needed for this application.

Unfortunately I can't remember specific numbers for my system when it's approaching blockage - I know how far round the gauge the needle goes for "normal", "getting a bit dirty", "needs replacing when convenient", "starting to falter", etc, but I don't recall the actual scale. However, I'm pretty sure it's a lot more than the 0.02bar that sensor covers.

Pete
 
prv said:
That's an interesting device, but I doubt it has the pressure range needed for this application.

Unfortunately I can't remember specific numbers for my system when it's approaching blockage - I know how far round the gauge the needle goes for "normal", "getting a bit dirty", "needs replacing when convenient", "starting to falter", etc, but I don't recall the actual scale. However, I'm pretty sure it's a lot more than the 0.02bar that sensor covers.
Click to expand...

You're right; nowhere near enough. The Racor vacuum gauge I had on my last boat had a yellow warning sector starting at about 25kPa, and a red warning sector starting at about 35kPa. Once the needle got in to the red, the filter was starting to struggle to suck fuel through.
 
Thanks for the info on vacuums that may be encountered on a block or semi blocked filter.

That particular one is as you say too low but I originally looked at it measure the pressure differential for a venturi fuel flow meter where the pressure differently would be very small at the low flows we look at.

There are others with higher pressure differential and using this type of device would allow multi filter montering and to measure the pressure differential in a filter in a pressure line between the lift pump and the injector pump.

By if you wish to rubbish the idea do for it.

Here's 5 off that measures up to 300mmhg about 0.4 bar 40Kpa

Ok not different but allow for an alarm to be sound. at lets say 30Kpa.
 
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prv said:
Not at all - I think it’s a great idea (with the right part) and now I’m sort of tempted to do the same even though I have no real need ;)
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No need to re-invent the wheel! Racor sell a vacuum switch which closes at 24kPa, the start of the yellow warning sector on their vacuum gauges.
 
prv said:
Not at all - I think it’s a great idea (with the right part) and now I’m sort of tempted to do the same even though I have no real need ;)

Pete
Click to expand...

Differential Pressure Sensor ICs - online | RS Components

Pete RS seem to have lots of more robust ones on the above page with different ranges to suit the application

This data sheet is foe a 50Kpa but lots of other specs are available

https://docs.rs-online.com/da38/0900766b814f5256.pdf

My comment was not aimed at you pete.
 
pvb said:
No need to re-invent the wheel! Racor sell a vacuum switch which closes at 24kPa, the start of the yellow warning sector on their vacuum gauges.
Click to expand...

At what cost.

If what is off the shelf is OK by you but I design thinks with improved functionality and have made and saved a lot of money by doing so
 
pvb said:
Here you go again! Can you point to anything I said to "rubbish the idea" as you alleged? You really need to get a grip of yourself.
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Here we go again
It looks like you are a bit sensitive as you assumed I was referring to you.

o_O o_O o_O o_O o_O o_O o_O

Answer my question what id the cost of the piece of equipment you posted in stead of "Re inventing the wheel" isn't the "rubbish the idea"

I suppose you will claim you were just posting and alternative.

It seems you logic is quite different to mine.

No more replys.
 
Rogershaw said:
Here we go again
It looks like you are a bit sensitive as you assumed I was referring to you.
Click to expand...

I did assume that. Only prv responded to your post, and I responded to him. As you said it wasn't prv, that doesn't leave many alternatives...

You must stop trying to argue.
 
Was about to order two WIKA +-1bar gauges to fit on my Separ prefilters . It's going to be much cheaper to fit two senders from farnel and wire them to the existing arduino feeding the NMEA2000 bus with data. Only I'm not sure there's a PGN for filter pressure! Got to check that, would be easy to get a general engine warning though Ata set vaccum...
 
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