August 20 (SeeNews) - Bulgarian machine engineering company Hydraulic Elements and Systems (HES) [BUL:HES] said on Friday that its sales revenue rose by 25.47% year-on-year in the first seven months of 2021, to 38.6 million levs ($23.1 million/19.7 million euro), after recording sales of 4.98 million levs in July alone.