Wouldn’t the easy answer be to just open the valve at the back until the weighbridge op tells you you’re legal? The overloading will soon stop when your boss and the consignor have to split the clean up bill 
Zac_A:
I’m quite happy to have any misunderstandings of mine corrected, but I think for 100% certainty we really need something more up to date than VOSA guidance from 2012, their successor DVSA may potentially have different ideas.
It’s been the same since I started, which was 1986, and I’m sure that if it had changed we would have heard about it.
gazmac:
Liquid tanker,loaded with no weighbridge to confirm weight. Paperwork is all correct with the amount of capacity to be filled…on destination the weighbridge is telling me I’m overweight…What’s the law if involved in a accident…its happening quite often.
To all the replys for this post thankyou. Its still a frequent behavior, however I’m taking the advice of from all posta and acting accordingly…
gazmac:
gazmac:
Liquid tanker,loaded with no weighbridge to confirm weight. Paperwork is all correct with the amount of capacity to be filled…on destination the weighbridge is telling me I’m overweight…What’s the law if involved in a accident…its happening quite often.To all the replys for this post thankyou. Its still a frequent behavior, however I’m taking the advice of from all posta and acting accordingly…
Good luck to you.
Cover your arse, in whatever way you think is best for you. Protect your licence.
But doesn’t things like heat and weather have a effect on some substances and weight?
Franglais:
shullbit:
But if the driver educates himself with the facts about specific gravity etc, then he has something to go to war with.Your point is understood, but why complicate things?
If he has records of weights then what else does he need?The OP has said he has been overweight on more than one occasion, that is enough to know in my book.
Don`t give anyone the chance to twist things around.
I am educated, all I can say js the loading of vessels (tanks) are not. Eing monitored and the calibration maybe wrong…or excess liquid is being put on without record.
Harry Monk:
Zac_A:
I’m quite happy to have any misunderstandings of mine corrected, but I think for 100% certainty we really need something more up to date than VOSA guidance from 2012, their successor DVSA may potentially have different ideas.It’s been the same since I started, which was 1986, and I’m sure that if it had changed we would have heard about it.
Although VOSA originally published the guide in 2013 and it still has VOSA on the cover it is now released by the DVSA and is still linked to on the .gov website.
Macski:
But doesn’t things like heat and weather have a effect on some substances and weight?
Most liquids do expand when they get warmer, yes. Their density (and hence Specific Gravity) does change.
So, if a known amount by volume (litres) is loaded then a different weight will be loaded, true.
In my experience I`ve only loaded liquid foodstuffs, and they are store at fairly equal temperatures. Product coming from a production plant or underground storage might well always be about the same temp.
Weather (air pressure ?) will make no significant difference to the density of a pure liquid.
If the transporter says they can load a certain weight legally then the loading company should know the temp of their product, and it`s SG so load the correct amount. It is simple arithmetic.
Example:
If you can load 20T legally, then you can load 20,000 litres of water at 4deg C. OK?
So, what if the water is at 25deg C? A UK summer time temp.
SG water at 25C is 0.997047. So the 20,000l will be 19.94T
The load will be 60kgs short of the maximum possible allowed. About 3 jerry-cans. Approx SFA in the scheme of things.
If the company are approaching this from the other end. they want 20T in at 25deg C then approximately the opposite holds.
To load 20T at 25C they would load 20,060.18l. A smidgen over 60l more.
If that same volume were loaded at 4C it would be, not 20T but, the 60.18kgs too heavy.
All the above shows is that the amounts we are discussing are likely less than 100kg.
Less than half a tank of diesel. A little bit over a lard arse`s breakfast maybe, but nothing much IMHO to worry about.
I thought to add another commonly carried substance… Milk.
Remembering that
I:
25,000L of Water weighs 25,000Kg (Water = 1.0 compared to water) [Water is the same weight as Water!]
A liter of raw milk varies in weight depending on whether it’s summer (higher) or winter (lower) but a good average SG is 1.03, meaning that a liter of raw milk is slightly heavier than water.
Using an average SG figure of 1.03, then 25,000L of raw milk weighs 25.750Kg. All those little .03’s really add up, in this case making a 750Kg overload, which causes a bit more than a simple headache for both the driver AND the TM whose name is on the company’s ‘O’ licence. 
Assuming (as an example,) an authorised tank capacity of 25,000L, …an unsuspecting driver loading 25,000L of raw milk might be caught out with a (potentially) 750Kg overload (25,000 X 1.03 = 27,750Kg) if the pointy shoes in the office don’t take this into account.
If the authorised literage of the tank is 27,000L (27,000 X 1.03 = 27,810Kg) then the overload amount is 810Kg.
The most dense “(heaviest” liquid food I carried was concentrated grape juice. I am sure some chemicals are more dense, but that was the worst I had.
24t was 18,000 litres in a 26,000 litre container tank with no baffles…that took some getting used to. 
Ed to add, I also carried ■■■■ oil, and that was much less dense. The same 26,000l ISO woud contain just under 24T at full capacity. Much easier drive.
dieseldave:
gazmac:
Liquid tanker,loaded with no weighbridge to confirm weight. Paperwork is all correct with the amount of capacity to be filled…on destination the weighbridge is telling me I’m overweight…What’s the law if involved in a accident…its happening quite often.Hi gazmac,
Carrying on from Franglais’ very good advice above…
Due to liquids being of considerably different weights per liter, we calculate the weight of a liquid tanker load by reference to the weight of water.
1L of water weighs 1Kg, so then the substance to be carried is either…
Lighter than water, or
The same weight as water, or
Heavier than water.Some examples (round figures):
25,000L of Propane weighs 12,800Kg (1L of Propane weighs 0.5Kg, Water = 1.0) [Propane is lighter than water]
25,000L of Water weighs 25,000Kg (Water = 1.0 compared to water) [Water is the same weight as Water!]
25,000L of Bromine weighs 78,000Kg (1L of Bromine weighs 3Kg, Water = 1.0) [Bromine is heavier than water]Depending on the substance you carry, I might be able to tell you the weight of it if you tell us what it is and how much of it you carry.
How much overweight are you on the delivery customer’s weighbridge?
Oleum was the highest sg of any liquid I saw marked on a tanker prior to Liquid Bromine you mention here… I guess that only other liquid element at room temperature, formerly known as Hydragyrum tops even Bromine and Sulphuric Acid though…
Specific Gravity:
Hg 13.57
Br 3.12
H2SO4 1.84
I’ve seen Sulphuric Acid (98%, “Tech” quality) in small tankers marked “super heavy”, but have yet to see Mercury or Bromine in transport anywhere…
Must be a pretty rare one, like some of the truly lethal liquids out there, that don’t just corrode, poison, and damage the environment - but those “Pyrophoric” ones that set themselves on fire first and THEN create the poison gas cloud that kills everything in the air, before combining with rain water to poison the soil later on… Nasty Stuff.
NO2 compresses into N2O4, and reverses back again if the tanker carrying it crashes…
I mention this, as in the liquid and gas state - it looks remarkably like Bromine (Red/Brown toxic, heavy vapour that smells a bit like a chemical footbath/toilet)
I wouldn’t want to swap places with whoever was driving this tanker in Arizona recently…
dieseldave:
I thought to add another commonly carried substance… Milk.Remembering that
I:
25,000L of Water weighs 25,000Kg (Water = 1.0 compared to water) [Water is the same weight as Water!]A liter of raw milk varies in weight depending on whether it’s summer (higher) or winter (lower) but a good average SG is 1.03, meaning that a liter of raw milk is slightly heavier than water.
Using an average SG figure of 1.03, then 25,000L of raw milk weighs 25.750Kg. All those little .03’s really add up, in this case making a 750Kg overload, which causes a bit more than a simple headache for both the driver AND the TM whose name is on the company’s ‘O’ licence.
just aswel that milk tanker capacity is taking the weight of the milk into account. If, as in your example, 25.000 liters of milk would mean a 750kg overload, than the maximum authorised load would be 24.250 liters.
We, for example, load our barrels with a maximum of 28.500 liters, which gives a smidgen under 44.000 kg on the weighbridge.
the nodding donkey:
dieseldave:
I thought to add another commonly carried substance… Milk.Remembering that
I:
25,000L of Water weighs 25,000Kg (Water = 1.0 compared to water) [Water is the same weight as Water!]A liter of raw milk varies in weight depending on whether it’s summer (higher) or winter (lower) but a good average SG is 1.03, meaning that a liter of raw milk is slightly heavier than water.
Using an average SG figure of 1.03, then 25,000L of raw milk weighs 25.750Kg. All those little .03’s really add up, in this case making a 750Kg overload, which causes a bit more than a simple headache for both the driver AND the TM whose name is on the company’s ‘O’ licence.
just aswel that milk tanker capacity is taking the weight of the milk into account. If, as in your example, 25.000 liters of milk would mean a 750kg overload, than the maximum authorised load would be 24.250 liters.
We, for example, load our barrels with a maximum of 28.500 liters, which gives a smidgen under 44.000 kg on the weighbridge.
Hi ND,
Your office guys seem to be doing it just right because they’re allowing for the (averaged) + .03 difference between milk and water.
As I said, all those + .03’s add up.
I hope the OP’s office gets their act together!
Is it more dodgy to be driving a third of a tank or a half?
I’ve heard from several drivers that “Sloshing about” shifts the center of gravity so much that it is easy to roll it even going around a roundabouts/corners slowly…
“Load Shift” and “Live Animals” can also do that of course.
Dunno what makes a van driver so impatient that they just simply cannot wait for a few seconds for a safer spot to overtake…
Winseer:
Is it more dodgy to be driving a third of a tank or a half?I’ve heard from several drivers that “Sloshing about” shifts the center of gravity so much that it is easy to roll it even going around a roundabouts/corners slowly…
“Load Shift” and “Live Animals” can also do that of course.
Dunno what makes a van driver so impatient that they just simply cannot wait for a few seconds for a safer spot to overtake…
I`ve never carried animals, but thought there were internal pens to stop the beasts moving and crushing each other?
Road tanks may have multi compartments allowing very little ullage (free space)in the tank.
We did some dense (heavy) liquids in single compartment container tanks. Mostly fresh or concentrated fruit juices. Nearly a third of the tank was empty. Due to being food tanks, and the need for cleanliness no internal baffles were fitted.
In some tanks half height internal walls, with holes in the bottom, are fitted to reduce slop.
Yes, every time you brake, change gear, alter speed, and especially turn a corner the product will move around changing the C of G.
Slowing nice and gradually for any hazard seems to induce everyone to want to overtake and brake in front of you. Having 24 tons slide up the wall of a tank is not a pleasant feeling.
We had proper goose neck container trailers to get the C of G a little lower, but they still always needed treating with respect. The chassis arms that held the container tanks were subject to fatigue fracture because of the constant hammering as 24T slosh back and forth all the time.
I always much preferred running with with a proper road barrel.
I’ve not driven live animals nor liquids at all, but I remember thinking back when I was doing paper reels that the “shotgun loaded” ones were a lot more stable as a load than the “upright ones” strapped down with “corners”…
Driving the latter through London to places like Surrey Quays used to be a nightmare, because there would always be some tossers on the roads around the Blackheath/Shooter’s Hill Road area that would “brake test” me, resulting on one occasion in a fully-strapped reel shifting forward about a foot, which I heard clout the headboard of the trailer behind me… Lucky for me, it slid in a straight line, and stayed upright and on the trailer, rather than like this…
Winseer:
Is it more dodgy to be driving a third of a tank or a half?I’ve heard from several drivers that “Sloshing about” shifts the center of gravity so much that it is easy to roll it even going around a roundabouts/corners slowly…
“Load Shift” and “Live Animals” can also do that of course.
Dunno what makes a van driver so impatient that they just simply cannot wait for a few seconds for a safer spot to overtake…
Worst slop I’ve had was 9000l of milk in a single baffle one pot trailer, absolute pig to drive like that
Yes, milk tankers (and a lot of other food grade tankers I guess) have usualy no baffles, because it’s hard to get the corners clean, and especialy with milk, the residue sticks. They usually have a single, half height devider, with a large gap underneath aswel. The liquid can move back and fore freely… depending on the input from the driver.
To be fair, unsympathetic drivers don’t usually last very long, because driving a milk tanker badly, is very, very uncomfortable
There are twin compartment tanks, which limit the movement of the milk somewhat,but they have their own issues to catch out the unwary driver… 
.
Franglais:
Winseer:
Is it more dodgy to be driving a third of a tank or a half?I’ve heard from several drivers that “Sloshing about” shifts the center of gravity so much that it is easy to roll it even going around a roundabouts/corners slowly…
“Load Shift” and “Live Animals” can also do that of course.
Dunno what makes a van driver so impatient that they just simply cannot wait for a few seconds for a safer spot to overtake…
I`ve never carried animals, but thought there were internal pens to stop the beasts moving and crushing each other?
Road tanks may have multi compartments allowing very little ullage (free space)in the tank.
Whilst filling just the one compartment to reduce ullage in that compartment may stop the liquid moving, it will cause overloading of the front or rear of the trailer.We did some dense (heavy) liquids in single compartment container tanks. Mostly fresh or concentrated fruit juices. Nearly a third of the tank was empty. Due to being food tanks, and the need for cleanliness no internal baffles were fitted.
In some tanks half height internal walls, with holes in the bottom, are fitted to reduce slop.
Yes, every time you brake, change gear, alter speed, and especially turn a corner the product will move around changing the C of G.
Slowing nice and gradually for any hazard seems to induce everyone to want to overtake and brake in front of you. Having 24 tons slide up the wall of a tank is not a pleasant feeling.
We had proper goose neck container trailers to get the C of G a little lower, but they still always needed treating with respect. The chassis arms that held the container tanks were subject to fatigue fracture because of the constant hammering as 24T slosh back and forth all the time.
Another item that needs regular checking, and adjustment, is the kingpin, and the fifth wheel jaws adjustment. They get a battering, because even if you drive sympatheticaly, when you are stopped, the liquid keeps moving back and forth for a bit. Never mind when a lead footed driver pulls up at a roundabout after harsh braking, and then tries to pull away with his foot down…I always much preferred running with with a proper road barrel.
What’s one of them then?
the nodding donkey:
Yes, milk tankers (and a lot of other food grade tankers I guess) have usualy no baffles, because it’s hard to get the corners clean, and especialy with milk, the residue sticks. They usually have a single, half height devider, with a large gap underneath aswel. The liquid can move back and fore freely… depending on the input from the driver.To be fair, unsympathetic drivers don’t usually last very long, because driving a milk tanker badly, is very, very uncomfortable
There are twin compartment tanks, which limit the movement of the milk somewhat,but they have their own issues to catch out the unwary driver…
Used to do a bit of cream on export. Always needed a good hot wash with detergent to get it clean. As you say sticky, greasy, stuff.
The tanks with internal cleaning pipes needed checking around the heads to ensure they were clean. The bare tanks were easier to clean on the whole.
We pulled a few road barrels and they had some baffles inside, to do the job right it was best to get inside with a had brush around the corners. Yes, it was the responsibility of the tankwash to clean it, but the grief involved made it right for the driver to check and double check it. Our signature said we were happy with the job done.
White wine that tastes of coffee wasn`t a good selling point!