This looks a lot like the beans that Brazilians venerate and can be easily found in the United Kingdom as of 2020.
The more exact type seems to be pinto bean, but this is close enough.
2021-03: same but 2.5 teaspons, seems to be the right ammount.
2021-02-10: attempt 3: 500g 1 hour 30 minutes no pressure, uncontrolled water. Salt with one chorizo: put 3 teaspoons, it was a bit too much, going to do 2 next time and see.
2020-12-14: attempt 3: 250g of beans, 1.5l of water, 30 minutes pressure.
2020-11-30: attempt 2: 275ml of dry beans, about 50% of 500g bag, putting 1650 ml (6x) of water on pressure cooker Still had to throw out some water.
Density dry raw: 216 g/250 ml = 432 g / 500 ml = 500 g / 580 ml = 864 g/L
500 g dry expands to in water after 12 hours: 1200 ml
Therefore 500 g dry = 864 / 2 L = 432 ml expands about 3x.
Therefore, to the maximum 2.5L of the cooker with 8x dry volume water from this recipe I can use:
2500 = volume expanded bean + volume water = 3 volume dry bean + 8 volume dry bean = 11 volume dry bean
and so:
volume dry bean = 2500/11 = 227ml
which is about 227 / 580 = 40% of the 500 g bag.
After first try, I found that 8x volume of water is way, way too much. Going to try 6x next time.