Series 24-HP Instruction Manual | Chapter 1 Introduction |
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How the Innova-Mass Vortex Mass Flow Meter Operates
Figure 1-1. In-Line Vortex Multi-Parameter Mass Flow Meter
Sierra Series 240 and 241 Innova-Mass™ Multi-Parameter Vortex Mass Flow Meters use a unique sensor head to monitor mass flow rate by di- rectly measuring three variables–fluid velocity, temperature and pres- sure. The built-in flow computer calculates the mass flow rate and volu- metric flow rate based on these three direct measurements. The velocity, temperature and pressure sensing head is built into the vortex meter’s flow body. To measure fluid velocity, the flow meter incorporates a bluff body (shedder bar) in the flow stream and measures the frequency of vortices created by the shedder bar. Temperature is measured using a platinum resistance temperature detector (PRTD). Pressure measurement is achieved using a solid-state pressure transducer. All three elements are combined into an integrated sensor head assembly located downstream of the shedder bar within the flow body.
Velocity Measurement
The Innova-Mass vortex velocity sensor is a patented mechanical design that minimizes the effects of pipeline vibration and pump noise, both of which are common error sources in flow measurement with vortex flow meters. The velocity measurement is based on the well-known Von Kar- man vortex shedding phenomenon. Vortices are shed from a shedder bar, and the vortex velocity sensor located downstream of the shedder bar senses the passage of these vortices. This method of velocity measure- ment has many advantages including inherent linearity, high turndown, reliability and simplicity.
