DEFINITION:Key structure is made up of rotary carried helical blades which goes around as the same direction of water flow.CHARACTERS:Removable structure, easy installation and maintenance.Dry type, magnetic drive.Measuring system fit for uniform use.An obvious advantage is that the pressure loss is less than 0.01MPa which is only 10% of rotating vane type.Cast iron body.Transmission device.Best choice for water supplying companies.WORKING CONDITION:Water temperature≤ 45ºC(Hot water meter≤ 90ºC)Water pressure≤ 1MpaMAXIMUM PERMISSIBLE ERROR:From the minimum flow-rate (qmin)inclusive to the lower zone of the transitional flow-rate (qt ) exclusive: ± 5%.From the transitional flow-rate (qt ) inclusive to the higher zone of the maximum flow-rate (qmax ) exclusive: ± 2%(hot water meter± 3%. ).