In very dry regions and especially desert zones high rates of fine sand in the intake air can cause frequent maintenance intervals of downstreamed components or also to abrupt breakdown due to contamination. That is the reason why either filter often have to be changed or downstreamed components have to be cleaned regularly to guarantee a failure-free operation. The self-cleaning sand pre-filter with sand discharge ventilator makes possible longer maintenance intervals and improves durability of the remaining components (filter, ventilator, control element) in the ventilation system. Krapf & Lex therefore offers two possibilities:
Krapf & Lex multicyclone
The durability of downstreamed fine filters gets 20-30 times higher because of the pre-filtering with the multicyclone. The multicyclones from Krapf & Lex do have all the permissions necessary for railway vehicles such as the construction and production according to DIN EN 15085 or oscillation- and shock test according to DIN EN 61373. The multicyclone filter from Krapf & Lex is in use in the desert of Saudi Arabia between Damman and Riad. The fresh air for train staff and passengers is prepared by a pre-filtration designed by Krapf & Lex, before the air gets leaded, almost fully free of sand and dust, to the HVAC system. The durability of the fine filter installed in the HVAC systems therefore extremely increases.
Krapf & Lex Sand pre-filter
Compared to multicyclones, absorbing effectiveness is lower, but there is less pressure loss and it also needs little space. The sand pre-filter is in use in FLIRT Algeria. There the intake air gets pre-filtered for the ventilation system and the cooling system of the pneumatic air generator by the sand pre-filter.