MEMS Gas Flow Meter

Both measure gas mass flow by thermal-dispersion physics, but the sensor scale differs. A CTD (constant-temperature-differential) industrial thermal-mass meter uses a pair of heated wires inserted into a full-bore pipe; it serves DN50 to DN400 plant-scale gas billing at 0.2 Nm/s low-flow detection and Nm³/h output scale. The MEMS gas flow meter integrates the same heater-plus-thermopile principle onto a single silicon die in a DN8 to DN25 threaded micro-bore body, with a 0.05 Nm/s low-flow detection; four times more sensitive than CTD; and mL/min to kg/h output range covering lab analytical through OEM skid integration. Pick MEMS for any service below DN25 and any application needing mL/min resolution; pick thermal-dispersion inline for DN50+ industrial gas billing on biogas, natural gas, hydrogen, compressed air, nitrogen, or oxygen plant lines.

Three patterns. First, micro-flow detection; the 0.05 Nm/s velocity floor catches leak rates and weekend-purge drift that thermal-dispersion inline misses below its 0.2 Nm/s floor; on a DN10 line that is 0.3 NL/min of leak that MEMS sees and thermal-dispersion does not. Second, output unit resolution; mL/min and g/s lab-instrument units come native on the MEMS firmware, which CTD industrial firmware does not output (CTD is Nm³/h scale). Third, OEM integration cost; the MEMS micro-bore body with threaded ZG-1/4 to ZG-1 connections drops into a lab skid or OEM gas-supply module without flanges, weld-prep, or upstream straight-pipe footprint that thermal-dispersion inline demands. For any line under DN50 carrying clean dry gas, MEMS is the more cost-effective integration.

Standard factory calibration covers clean dry air, nitrogen, oxygen, argon, helium, methane, carbon dioxide, and hydrogen; each as a separate factory-loaded curve. For mixture gases with known composition (battery formation H₂/N₂ blends, semiconductor CDA/N₂ purge, calibration gas streams), factory calibration takes the buyer-specified mix at order time and ships a custom curve. The MEMS chip ships with a 5-curve memory slot, so one meter can carry up to five gas profiles selectable by digital register, which fits multi-gas lab service. Out-of-list gas chemistries (corrosive HCl, Cl₂, wet sour digester gas) are outside scope; route those services to the alternate family per the platform medium-binding rule.

It replaces the meter half of an MFC stack, not the controller half. A mass flow controller integrates a flow sensor, a proportional control valve, and a PID loop in one housing; the MEMS gas flow meter is the metering element only; it reads and reports mass flow without valve actuation. For lab and OEM applications where the buyer already has a control valve (manual needle valve, electronic proportional valve, or downstream solenoid), the MEMS meter pairs into the existing control loop via 4-20 mA or RS485 Modbus. Buyers who need the integrated valve-plus-meter MFC stack should specify a separate proportional valve at order, or source the MFC from a dedicated MFC vendor. The factory-direct MEMS gas flow meter price is typically 40 to 60 % of an equivalent-flow premium MFC because the actuator cost is removed.

Ex d II C T6 Gb is a flameproof-housing certification for explosive-atmosphere service, covering hydrogen-bearing atmospheres (gas group II C) at surface temperature up to 85 °C (T6 class) in Zone 1 hazardous area. This is the right rating for hydrogen lab service (electrolyzer test rig, fuel-cell test stand, hydrogen calibration), battery cell formation rooms where venting H₂ can collect, and chemical-process areas with solvent vapor presence. For non-hazardous lab and analytical service (standard GC carrier gas, oxygen lab supply, calibration gas), specify the standard environment option which ships at lower price without the Ex d housing. Both versions ship in 5–7 business days from the factory.

Three signal-output options cover the lab and OEM integration patterns. 4-20 mA analogue output (2-wire loop-powered or 3-wire externally sourced) integrates with industrial PLC, DAQ cards (NI cDAQ, Agilent, Yokogawa), and analog-input modules. RS485 Modbus RTU exposes the totalizer register, instantaneous flow, alarm status, and per-gas curve selection over serial; fits LabVIEW, Python pymodbus, and SCADA Modbus polling. HART (optional) supports HART-multiplexer rollouts in industrial OEM skids where field-instrument digital overlay is already deployed. Pulse output handles totalizer counting into PLC counter inputs or third-party flow computers. Up to two NO/NC contact channels support alarm threshold tripping and batch-control shutoff signalling at 24 V / 0.5 A.

Standard lead time is 5 to 7 business days from order confirmation, factory direct, including factory calibration for the specified gas. The meter ships with an ISO 9001 calibration certificate listing the serial number, calibrated gas type, and tested flow range, plus a mill-cert traceability note for the 304 / 316L wetted parts (heat number traceable to the steel mill). Ex d II C T6 Gb hazardous-area certification is the optional environment-class upgrade. EMC compliance to the EU Electromagnetic Compatibility Directive 2014/30/EU (Annex II) ships standard. The factory does not ship lab-specific qualification packages (USP, FDA, GAMP 5, IQ/OQ/PQ); buyers running validated lab environments source those documents from their own calibration program.