Pump unit with 3 pumps and 2 main pipes in HO Scale. The pipes can be connected at one or both sides. An unconnected side will pass as a blind flange used for maintenance etc. These units can be placed side by side, although 6 pumps would be a bit much. Each pump is 15.6mm long. Setups like this can be found at industrial sites, sprinkler rooms, water pump stations, filtration units etc.