Hi Dave,
Can I drag you (kicking and screaming, probably) back to “bowsers”? I’ll try to be as specific as I can, but I’m sure you’ll come back with requests for data I’ve not supplied 
Anyway…
A charity I volunteer with (not the same one as I’ve asked you about before) has a number of items of plant (excavators, generators, cement mixers, etc.) that run on red diesel (UN1202, Class 3, PG III, I believe). At the moment, the way they’re buying red diesel means they’re paying the retail “pump” price.
They’re looking at getting a 5000-litre bunded tank so that they can get it delivered at the wholesale price - they’re using enough of it that the tank will repay itself in savings in a few months.
The bunded tank will stay at their depot, so AIUI is irrelevant from an ADR perspective.
However, they’re looking at getting a bowser trailer for transporting it from the depot to the plant on site - filling up an excavator using jerrycans can be a bit of a PITA…
I think the most likely option would be a purpose-built bowser trailer (i.e. tank permanently fixed to the body of the trailer). From reading your earlier replies, I believe this is defined as a “tank”?
It’s possible, though, that they may go for an IBC/portable tank carried on a plant trailer (and therefore a “package”?) - something like this: jerrycans.co.uk/cemo-dt-mobi … -449-p.asp .
It will be towed behind either a Transit-size van or a pickup.
Again, from reading your earlier replies, they can stay out of “full” ADR by staying under the 1000 litre capacity limit; is this true for both the “tank” and “package” option? Also, I realise that they’ll still require the 2 kg fire extinguisher plus (recorded) training etc. What is the lower limit where this comes into effect? How much UN1202 do you have to be carrying before you start to come under the “reduced” ADR requirements? I had assumed that a single jerrycan would be exempt, but doing a bit of research, LQ appears to be 5 litres, so if someone were carrying a single 20 l metal jerrycan (non-private use), are they still coming under ADR (albeit a “small load”)?
Is there a (realistic) way that the charity can stay out of ADR entirely? I think that suggesting that they buy a mountain of 5 l jerrycans to stay within LQ is likely to be met with raucous laughter 
I also noticed the following paragraph on the HSE website:
Bowsers are commonly towed by vans, 4 x 4s etc. Where the bowser is not an IBC (either conventionally or via authorisation no. 1), then the towing vehicle should meet the AT or FL standards as appropriate for the substance being carried (ADR 9.1.2.3)
Does that mean that, if they go down the “tank” route, they have to use a specially tested/modified vehicle to tow it? Actually, looking at the definitions of those codes, AT and FL only seem to apply where the capacity is over 1000 l, so I think I’ve answered my own question
Thanks in advance…