The best way lock off Diesel bowsers, which are basically diesel tanks on a trailer, is an outdoor padlock with a long enough loop to secure it but without it being too long so that it gets in the way of other fittings. The padlock shackle generally needs to be a minimum inner height of 40mm but ideally no longer than 90mm and with a minimum inner width of 20mm. The hole in the fitting is normally around 18mm so plenty of space to fit a padlock loop through. As these trailers will often be on the road or left outside in harsh remote places, the padlocks really need to be good in all weathers.
Here are a couple of options depending on your security level requirements. These padlocks fit the measurements discussed earlier and either of the locks would be suitable for use in harsh environments. Both of the products can be produced in key differ or keyed alike versions to give flexibility in how access is granted to the diesel tanks.
The Abus Eterna 41/50HB50 steel laminated padlock is a highly superior lock and is not to be confused with the cheaper alternatives you can now find on the market. Abus have developed a treatment process which gives their laminated padlock a long lifespan. They are of course keeping this treatment process highly secret but it does give a steel lock with high grade weather resistance and strength.
Alternatively, where you need a higher level of security, the long shackle Abus Granit 37/55HB50 is suitable for prolonged periods outdoors. It comes with a specialist coating ensuring it is fully weatherproof to marine grade standard. Ideal when taking your diesel trailers all over the country. The removable shackle feature also means it is so much easier to fit on those diesel tanks with restricted access.
