device.rb

class Device
  CONSUMPTIONS = {
    "1" => { method_id: 2, value: 20 },
    "2" => { method_id: 6, value: 0.001 },
    "3" => { method_id: 7, value: 30 }
  }
end

puts Device::CONSUMPTIONS["2"][:method_id] # => 6
puts Device::CONSUMPTIONS["2"][:value] # => 0.001

puts Device::CONSUMPTIONS.inspect # => {"1"=>{:method_id=>2, :value=>20}, "2"=>{:method_id=>6, :value=>0.001}, "3"=>{:method_id=>7, :value=>30}}