NDIR against Metal Oxide Films in CO2 Measurement
NDIR sensors provide definitive CO2 accuracy through direct mid-IR light absorption, while low-cost metal oxide films infer CO2 via prone cross-reactive surface chemistry.
Mass Flow Controller
Closed Control
Self-contained flow regulation instruments integrate fluid flow sensors, control valves, and closed-loop electronics to maintain precise gas mass flow rates. A mass flow controller regulates gas delivery independently of variations in inlet pressure or ambient temperature. This instrument governs flow accuracy in semiconductor manufacturing and sensor calibration manifolds.
Operational boundaries restrict control to clean, dry gases, stopping when condensation, particulate contamination, or liquid phase fluids enter the flow path. Internal PID algorithms compare real-time sensor measurements against setpoint commands to adjust proportional valve positioning continuously.
Thermal Sensing
Thermal flow sensors measure heat transfer across a heated capillary tube to determine mass flow. Inside a mass flow controller, bypass structures divert a fixed ratio of total gas flow through the sensor tube. Gas specific heat capacity factors calibrate sensor response for target gases.
Valve Actuation
Electromagnetic proportional valves adjust orifice openings to regulate gas velocity. Mechanical spring mechanisms close the valve upon power loss to ensure system safety. Valve response time limits overall flow adjustment speed.
Metrological Calibration
Primary standard piston meters verify mass flow accuracy across specified operating ranges. Calibration certificates list measurement uncertainty, repeatability, and zero-point stability under reference pressure conditions. Annual calibration ensures compliance with quality management systems.