Economical Analog Mass Flow Controllers
Designed to control the flow of air and ALL inert gases & mixtures, our MassTrak® Model 810C meets the same performance criteria as any industry-standard MFC at an affordable price. Our Model 810C is available with a large LCD readout and provides two simultaneous analog output signals, 0-5 VDC and 4-20 mA. The control valve features a purge mode and a valve close command from an external contact. The built-in setpoint control and simple 24 VDC power supply eliminate the need for a separate power supply and readout electronics that can cost as much as a new MFC.
Sierra's Model 810C is available in your choice of engineering units at flow ranges from 0-10 sccm to 0-50 slpm. The 810C uses Sierra’s Platinum Sensor Technology to eliminate zero-drift and create excellent long-term reliability.
- Accuracy of +/- 1.5% of full scale
- Direct monitoring of mass flow rate
- Flow ranges from 0-10 sccm to 0-50 slpm
- User-selectable local or remote set point
- Large LCD readout
- Use with ALL inert gases and mixtures
- “Primary Standard” calibration for best accuracy & NIST traceability
- CE approved
The 810 MassTrak Flow Sensing Principle
The operating principle of Mass-Trak transducers is based on heat transfer and the first law of thermodynamics. During operation process gas enters the instrument's flow body, where it encounters the laminar flow bypass. The laminar flow bypass generates a pressure drop, P1~P2, forcing a small fraction of the total flow to pass through the sensor tube (m1). The remainder of the flow continues through the body (m2).
Two resistance temperature detector (RTD) coils around the sensor tube direct a constant amount of heat (H) into the gas stream. In actual operation, the gas mass flow carries heat from the upstream coil to the downstream coil. The resulting temperature difference (OT) is detected by the RTD coils and gives the output signal. Since the molecules of the gas carry away the heat, the output signal is linearly proportional to gas mass flow.
The RTD coils are legs of a bridge circuit with an output voltage in direct proportion to the difference in the coils' resistance; the result is the temperature difference (OT). Two other parameters, heat input (H) and coefficient of specific heat (Cp) are both constant. The resulting output is nearly linear over the transducer's normal operating range.
For mass flow controllers, once the gas flows through the monitoring section, it is then controlled by the built-in servo-control valve. All models of the Mass-Trak utilize Sierra's proprietary high efficiency Fast-Trak Electromagnetic Valve. The normally closed Fast-Trak valve is similar to an on/off solenoid valve, except that the current to the valve coil, and hence the magnetic field, is modulated so that the ferromagnetic valve armature, or valve plug, assumes the exact height above the valve's orifice required to maintain the valve's command flow. The result is nearly infinite resolution.