Dwyer Instruments, LLC d/b/a DwyerOmega products

The gas mass flow controllers of FMA5400A/5500A Series provide for controlling the flow of a wide variety of gases from 0-10 SCCM up to 100 SLM. Utilizing heat transfer through a heated tube to measure molecular gas flowrate, the FMA5400A/5500A provides measurement of direct gas mass flowrate, without the need to compensate for variations in gas temperature or pressure (within stated limits). They are available in an economical aluminium/brass construction for typical gas flows and a 316 SS construction for applications requiring more corrosion resistance. The FMA5400A series without integral display is supplied with both an analog 0-5 Vdc and 4 to 20 mA output for remote monitoring; the FMA5500A series has both an integral 3-1/2 digit display and analog output. The display is tiltable over 90 degrees for viewing convenience. The display is calibrated standard to read out directly in SCCM or SLM for nitrogen (other gas calibrations available on special order).

The FMA-2600A Series mass and volumetric flow controllers use the principle of differential pressure within a laminar flow field to determine and control mass flow rate. A laminar flow element (LFE) inside the meter forces the gas into laminar (streamlined) flow. Inside this region, the Poiseuille equation dictates that the volumetric flow rate be linearly related to the pressure drop. A differential pressure sensor is used to measure the pressure drop along a fixed distance of the LFE. This, along with the viscosity of the gas, is used to accurately determine the volumetric flow rate. Separate absolute temperature and pressure sensors are incorporated and correct the volumetric flow rate to a set of standard conditions. This standardized flow rate is commonly called the mass flow rate and is reported in units such as standard cubic feet per minute (SCFM) or standard liters per minute (SLM).