Differential pressure flowmeter is a kind of flowmeter with long history and most user. The orifice device is the primary test units. With meters such as differential pressure transmitter, flow dispaly and adjuster, it may measure and control the instantaneous and accumulated flow of liquid, steam and gas, it has advantage of mature technology, wide application scope, simple installation and maintenance, well repeatability and long service life, and is widely used in industries such as petrochemical processing, natural gas, metallurgy, power, water conservancy, food and environment protection.

When fliud filling in pipes flow through orifice devices inside of pipes, fluid will form local contraction at orifice device, and consequently flow velocity increases and static pressure decrease, then pressure drop or preesure difference is caused in front of or behind orifice parts, the faster the flow velocity of medium is, the parger the pressure difference caused in front of or behind orifice part is , therfore, the fow of fluid may be measured by pressure difference. 
Characteristics and technical indexes

1. Lots of media applicable for measure, wide application scope
2. Mature technology, reliable
3. Standardized production, well repeatability
4. Long service life, simply maintenance