You fill supply tank first so that fuel weight is fed to lock out valves on branch pipe.
Idea is that if no pressure is fed to lock out valves on either side of tank branch pipe eg link pipe is damaged under the chassis,the fuel dont ■■■■ all over the road.
Always fill running tank first or lock out valves will shut off link pipe and starve running tank while auxilliary stays full.
Bking:
You fill supply tank first so that fuel weight is fed to lock out valves on branch pipe.
Idea is that if no pressure is fed to lock out valves on either side of tank branch pipe eg link pipe is damaged under the chassis,the fuel dont ■■■■ all over the road.
Always fill running tank first or lock out valves will shut off link pipe and starve running tank while auxilliary stays full.
Thats all nice and techy, but I’ve never had a problem with fuel starvation or heard off it on a master(running) tank slave(auxiliary) tank set up. I’ve heard off it happening several times on the the old twin feed system Renault used to use, probably why they stopped using it. 
ps the twin feed system had no link pipe running beneath the chassis, so no chance for it to get damaged. Funny how sometimes progress seems to go backwards
eddie snax:
Bking:
You fill supply tank first so that fuel weight is fed to lock out valves on branch pipe.
Idea is that if no pressure is fed to lock out valves on either side of tank branch pipe eg link pipe is damaged under the chassis,the fuel dont ■■■■ all over the road.
Always fill running tank first or lock out valves will shut off link pipe and starve running tank while auxilliary stays full.Thats all nice and techy, but I’ve never had a problem with fuel starvation or heard off it on a master(running) tank slave(auxiliary) tank set up. I’ve heard off it happening several times on the the old twin feed system Renault used to use, probably why they stopped using it.
ps the twin feed system had no link pipe running beneath the chassis, so no chance for it to get damaged. Funny how sometimes progress seems to go backwards
No Link? So if one tank runs out of fuel what stops the pump drawing air from the empty tank stack pipe?
Bking:
eddie snax:
Bking:
You fill supply tank first so that fuel weight is fed to lock out valves on branch pipe.
Idea is that if no pressure is fed to lock out valves on either side of tank branch pipe eg link pipe is damaged under the chassis,the fuel dont ■■■■ all over the road.
Always fill running tank first or lock out valves will shut off link pipe and starve running tank while auxilliary stays full.Thats all nice and techy, but I’ve never had a problem with fuel starvation or heard off it on a master(running) tank slave(auxiliary) tank set up. I’ve heard off it happening several times on the the old twin feed system Renault used to use, probably why they stopped using it.
ps the twin feed system had no link pipe running beneath the chassis, so no chance for it to get damaged. Funny how sometimes progress seems to go backwards
No Link? So if one tank runs out of fuel what stops the pump drawing air from the empty tank stack pipe?
Nothing, it was a bit off a problem, Only one tank had a fuel level sender unit, you needed to make sure that the breather pipes on each tank were regularly blown through with an air pipe( to prevent a vacuum forming, this was enough to stop diesel flowing), our fitters started doing it as one off the service jobs. this tended to keep that problem at bay
eddie snax:
Bking:
eddie snax:
Bking:
You fill supply tank first so that fuel weight is fed to lock out valves on branch pipe.
Idea is that if no pressure is fed to lock out valves on either side of tank branch pipe eg link pipe is damaged under the chassis,the fuel dont ■■■■ all over the road.
Always fill running tank first or lock out valves will shut off link pipe and starve running tank while auxilliary stays full.Thats all nice and techy, but I’ve never had a problem with fuel starvation or heard off it on a master(running) tank slave(auxiliary) tank set up. I’ve heard off it happening several times on the the old twin feed system Renault used to use, probably why they stopped using it.
ps the twin feed system had no link pipe running beneath the chassis, so no chance for it to get damaged. Funny how sometimes progress seems to go backwards
No Link? So if one tank runs out of fuel what stops the pump drawing air from the empty tank stack pipe?
Nothing, it was a bit off a problem, Only one tank had a fuel level sender unit, you needed to make sure that the breather pipes on each tank were regularly blown through with an air pipe( to prevent a vacuum forming, this was enough to stop diesel flowing), our fitters started doing it as one off the service jobs. this tended to keep that problem at bay
Bit of a Problem .Blow off a non return valve?
Anything is possible in la la land
Fuel levels senders is a thing I did not take into account.
■■? FFS
Bking:
eddie snax:
Bking:
eddie snax:
Bking:
You fill supply tank first so that fuel weight is fed to lock out valves on branch pipe.
Idea is that if no pressure is fed to lock out valves on either side of tank branch pipe eg link pipe is damaged under the chassis,the fuel dont ■■■■ all over the road.
Always fill running tank first or lock out valves will shut off link pipe and starve running tank while auxilliary stays full.Thats all nice and techy, but I’ve never had a problem with fuel starvation or heard off it on a master(running) tank slave(auxiliary) tank set up. I’ve heard off it happening several times on the the old twin feed system Renault used to use, probably why they stopped using it.
ps the twin feed system had no link pipe running beneath the chassis, so no chance for it to get damaged. Funny how sometimes progress seems to go backwards
No Link? So if one tank runs out of fuel what stops the pump drawing air from the empty tank stack pipe?
Nothing, it was a bit off a problem, Only one tank had a fuel level sender unit, you needed to make sure that the breather pipes on each tank were regularly blown through with an air pipe( to prevent a vacuum forming, this was enough to stop diesel flowing), our fitters started doing it as one off the service jobs. this tended to keep that problem at bay
Bit of a Problem .Blow off a non return valve?
Anything is possible in la la land
Fuel levels senders is a thing I did not take into account.
■■? FFS
That’s what our fitters said the few times they got a call :roll: 
These were H reg through to N reg Turboliners and Majors. The fleet then moved onto mid lift Premiums from about 96, they only had 1 one tank
Don’t know if it is relevant, but one vehicle I drove had 3 tanks. The two auxilary tanks were plumbed to the main with one way valves. So if there was more fuel in the main, it would not feed to the aux. But if there was more fuel in the Aux, they would drip feed the main.
Main tank was 200 litres, aux tanks were 1 x 200 and 1 x 300 litres. Was on a Daf 45 7.5 ton flat.
(There was a second 300 litre tank, but this was blanked from the other tanks as it was used for carrying cherry to on site fork lifts. )
Had it on a scania once
Driver filled second tank as didnt want to wait for other pump
Main tank was near on empty
50 miles later on hard shoulder
Scania came out had to pump across
Truck was using more than was flowing across