diesel flow sensor lt/min ratings for various HP engines

[jrudge]

Also assuming the error is uniform ( and i see no real reason why it would not be) you can compensate for the errors over a few fill ups to get it right.

The CAT system on my Squadron 65 is good ... but at idle it says 0 lph and then under reads until the engines are spinning nicely.

If I fill up, head out ( as i did from Sardinia to Menorca) they are very very accurate - about 10l over a 3000 odd litre burn which will be within the margin for error of the pump clicking on fill up.

For general use with high speed and low speed I get an error of from memory 50-100 lts depending on how much slow running i do - i dont pootle often but if there is not far to go and the sea is flat it is a nice way to spend half an hour trigging down the coast.

I called CAT and they looked at the test sheet and said - oh yes it does that doesn't it. They promised to come back to be but didn't. Maybe i will chase one day!

 

[Portofino]

I don,t think fuel flow is the be all and end all .
As said you should be able find out from the maker the consumption curve and plot rpm and L/hr - near enough
That's what i did with a Vp powered boat .
MAN seem to measure every thing with MMDS systems -about 18 things here's the last 3 on the 4th page
I think we are doing 10 knots here

 

[vas]

Also assuming the error is uniform ( and i see no real reason why it would not be) you can compensate for the errors over a few fill ups to get it right.

The CAT system on my Squadron 65 is good ... but at idle it says 0 lph and then under reads until the engines are spinning nicely.

If I fill up, head out ( as i did from Sardinia to Menorca) they are very very accurate - about 10l over a 3000 odd litre burn which will be within the margin for error of the pump clicking on fill up.

For general use with high speed and low speed I get an error of from memory 50-100 lts depending on how much slow running i do - i dont pootle often but if there is not far to go and the sea is flat it is a nice way to spend half an hour trigging down the coast.

I called CAT and they looked at the test sheet and said - oh yes it does that doesn't it. They promised to come back to be but didn't. Maybe i will chase one day!

very reassuring to know such large variations, thanks!
I can get 10euro sensors and when asked, I will say CATs on a SQ65 are similarly inaccurate
Would be interesting to chase it up and see what they say.

I don,t think fuel flow is the be all and end all .
As said you should be able find out from the maker the consumption curve and plot rpm and L/hr - near enough
That's what i did with a Vp powered boat .
MAN seem to measure every thing with MMDS systems -about 18 things here's the last 3 on the 4th page
I think we are doing 10 knots here

10kn and 24l/h is fine, but 61% load??? isn't that a bit odd?

So what you're implying is that if I get the curve, test it I could program it and get my consumption based on revs only? doubt it somehow (and it's not fun!)

cheers

V.

 

[jrudge]

I assume it is that at low RPM the flow rates are just not high enough to register with the electronics. I do however find it odd!

 

[vas]

I assume it is that at low RPM the flow rates are just not high enough to register with the electronics. I do however find it odd!

makes sense, but isn't the system employed by CAT just reading the ECU of the engine and doing some maths? surely they are not measuring actual flow of diesel through the pipes, no?

cheers

V.

 

[Portofino]

61% load @10 knots
14-55 M overall length -then less for WL length ( bow and B platform off ) -so I think I,am pushing a bow wave .
@825 rpm the fuel flow drops to 17 L/hr and speed to 9 knot s -thus by "having fun. " playing around is what I found my optimal poolting speed vs economy .
Also the props have a v steep pitch -so the engine via a big pitched prop is starting to push the boat past it's D speed ,hence 61 % load -
Once it pops (17-18,knotsv) - up and planes the speed increase s disproportionally with the rpm and load .

Also plying around
85 % load = 1750 rpm but 28 knots ---- l/h is around 85 This seems to be a sweet spot all day cruising speed

95% load is arround 2000 rpm 34 knots but 120l/hr and a bit noisey -fast cruise -Italian tune up

-WOT is 2150 and I never go there .-

So I guess if you can for a few 100 € find the L/hr then you can work out optimum D speed and P speed
Rarther than be a few100 rpm either side for hours on end .

 

[jfm]

makes sense, but isn't the system employed by CAT just reading the ECU of the engine and doing some maths? surely they are not measuring actual flow of diesel through the pipes, no?

cheers

V.

Correct. Cat isn't measuring fuel flow; it is merely deducing it from a look up table based on the ECU's message to the injectors telling them how long to squirt fuel in for. That's perfectly ok, and it seems they add a safety factor so they over state fuel burn slightly
Jrudge, your zero reading is therefore weird and feels like a software glitch

 

[superheat6k]

Accurate liquid flow measurement is a very difficult area for engineering generally, and for instance most building systems actively using various liquid flow system do not try to accurately measure this for control purposes, instead pressure drops are more commonly used to compute flow as an estimation.

The problem with marine diesels is the variable quantities in both supply and spill returns lines, which are not only affected by engine power setting, but also temperature and consequent liquid viscosity, and even filter blockage %. To accurately measure consumption relatively large quantities of fuel are flowing to and from the engine, with only a small part actually being burnt in the engine, and this exacerbates further the ability to precisely gauge fuel consumption by deducting spill return from flow supply.

This means even if you have two fairly accurate flow sensors, say reading + - 1% each, and say ~90% is being the returned in the spill line, the inaccuracy in the return qty will be ~ 9 x the inaccuracy in the flow. So this means at best you can only measure the accuracy of the burnt fuel usage to ~ 20%.

(The maths here are: 100 out +-1% so 99 to 101 out. 90 back so 90 + -1%, so 89 to 91 back. This means the consumption is Min 99 - 91 = 8 Max = 101 - 89 = 12. Range = 8 to 12 or 10 + - 20%)

If your metering sensors only achieve 5% accuracy the result here will be way out.

This is why a decent dual comparison flow meter is not cheap.

I would use the programming of the Arduino to use other factors to estimate fuel flow / burn, and the on thing that is relatively constant will be engine revs, but of course these will be affected by hull and prop cleanliness.

If you do suss a decent way of getting a + - 10% consumption result cheaply I would deb interested to learn more.

 

[vas]

not a full year passed since last post and being the OP, I guess I'm allowed to post

Found a sensor that looks promising, inquired, a guy came back to me from Prague and I'm waiting for an update (but that was before xmas!).
Wasn't sure if I could go for 250lph (each way) for my 330bhp 6.7lt 6cyl diesels, looks like they should be okay so I'm planing to go ahead and buy ONE and test it. Note, it's differential so two individual chambers two measurements, does the temp compensation and finds the diff and reports that.
Reports in either pulse output, RS232, RS485 or CAN j1939. Scratching my head on what's the easiest to work on (definitely NOT pulse!), but I should be able to convert the data and throw them in the NMEA2000 bus.

I'm looking at the DFM250 model: https://www.jv-technoton.com/fuel_flow_meter/differential_fuel_flow_meter

If anyone has tried them or has any reason I shouldn't go ahead please let me know!

cheers

V.

 

[superheat6k]

Looks like an interesting bit of kit. Interesting that their own diagram shows injector spill return on a separate pipe to the tank. If this were the case not all spill fuel would be measured which would make the results inaccurate.

Let us know how you get on with it.

 

[vas]

Looks like an interesting bit of kit. Interesting that their own diagram shows injector spill return on a separate pipe to the tank. If this were the case not all spill fuel would be measured which would make the results inaccurate.

Let us know how you get on with it.

I noticed this diagram and was confused, asked and they confirmed that you "wire" it as we think you should Trev.
I'll probably order one the following weeks unless I manage to go to Dusseldorf in which case I'll postpone just in case I find something interesting there.
As I said, main concern is if I can be OK with the 250lph, but my separs are thereabouts and never had a problem, so guess I'll gamble and get that.
I'm afraid that the larger one will be inaccurate in low flows.

we shall see and I'll report back of course.

cheers

V.

 

[NBs]

slightly odd question, but necessary for my next move and purchases.
Trying to setup a diesel flow meter as a cheap alternative to the v.expensive Floscan using arduino, CANBus and NMEA2000 output. Keep in mind that yes I don't want to spend thousands for flow meter, but similarly I wont die if the rate is .5l/h off, I can live with that if the cost of the system is 100-200euro...

My boat has 2 IVECO8061SRM33 330hp turbodiesel engines and my problem is that I don't have a clue what is the flow rate of my fuel pumps. I need to buy sensors that are suited to the particular ranges.
So main Q is there a rule of thumb or specs that I can use to do my calculations?
Would a say 40-160lt/h range be enough? (not that I have one in mind!)

Second Q is the damper seen on the Floscan a really necessary option or can I skip that with a possible small discrepancy in values recorded?

Latestarter, other diesel experts, open to suggestions.
Seems that there's a load of hall sensors suitable for diesel with varying ranges in usually lt/min.

cheers

V.

Hi,

I think Cummins 6BTA 330hp is same constructios whith Iveco, and Cummins fuel pumps flow is 258 litres.

Fuel System1
Approximate Fuel Flow to Pump .......................................................................... litre/hr [GPH] 258 [68] Maximum Allowable Fuel Supply to Pump Temperature.......................................... °C [°F] 60 [140] Approximate Fuel Flow Return to Tank............................................................litre/hr [GPH] N.A. Approximate Fuel Return to Tank Temperature......................................................... °C [°F] N.A. Maximum Heat Rejection to Drain Fuel5 ........................................................ kW [BTU/min] N.A. Fuel Transfer Pump Pressure Range ......................................................................... kPa [PSI] 124-172 [18-25]

NBs

 

[vas]

Hi,

I think Cummins 6BTA 330hp is same constructios whith Iveco, and Cummins fuel pumps flow is 258 litres.

Fuel System1
Approximate Fuel Flow to Pump .......................................................................... litre/hr [GPH] 258 [68] Maximum Allowable Fuel Supply to Pump Temperature.......................................... °C [°F] 60 [140] Approximate Fuel Flow Return to Tank............................................................litre/hr [GPH] N.A. Approximate Fuel Return to Tank Temperature......................................................... °C [°F] N.A. Maximum Heat Rejection to Drain Fuel5 ........................................................ kW [BTU/min] N.A. Fuel Transfer Pump Pressure Range ......................................................................... kPa [PSI] 124-172 [18-25]

NBs

thanks considering I now have SEPAR 2000/6 which are rated at 280 or 300lph and the fact that I really dont care what the consumption is at WOT (not even sure I want to see it if I have to do WOT ), I should be fine with the 250lph senders they offer, next size up is 500 which I find way too large!

cheers

V.