The FMA-LP2600A Series mass 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 centimeters per minute (SCCM) or standard liters per minute (SLM).
The controller uses a true proportional valve coupled to the flow body to control flow using the integral PID loop controller. Standard units include a 0 to 5V output (4 to 20 mA optional) and RS232 communications. The gas-select feature and the setpoints can be adjusted from the front keypad or via RS232 communications. Volumetric flow, mass flow, absolute pressure, and temperature can all be viewed or recorded through the RS232 connection. It is also possible to multi-drop up to 26 units on the same serial connection to a distance of 46 m (150').
Specifications Accuracy: ±(0.8% of reading + 0.2% FS) Repeatability: ±0.2% FS Turndown Ratio: 200:1 Control Response Time: 100 ms Input Control Signal: 0 to 5 Vdc, RS232 Output Signal: 0 to 5 Vdc, RS232 Optional Input/Outputs: 4 to 20 mA, 0 to 10 Vdc Operating Temperature: -10 to 50°C (14 to 122°F) Zero Shift: 0.02%/ATM FS/°C Span Shift: 0.02%/ATM FS/°C Humidity Range: 0 to 100% RH, non-condensing Excess Flow Rate: 2.4% FS Wetted Materials: Standard: 303 and 302 SS, FKM, silicone RTV (rubber), glass-reinforced nylon, aluminum, brass, 410 SS, silicone, glass; >250 SLM: 416 SS and nickel replace brass -LSS (Option):316LSS, 303SS, 430FRSS, Perfluoroelastomer standard, FKM, EPDM, Buna, Neoprene Maximum Pressure: 50 psig To Use in Volumetric Mode: Near atmosphere, 15 psig recommended maximum. Volumetric flow meters and controllers not certified for accuracy at mass flow rates above the rated flow range of the meter. They are designed for near atmospheric pressure conditions only. The recommended maximum operating pressure is 15 psig Supply Current: 0.250 A for 20 SLM and under; 0.75 A for 50 SLM and above (typical) Supply Voltage: 15 to 30 Vdc for units 2 SLM and smaller; 24 to 30 Vdc for units 5 SLM and larger Electrical Connections: 8-pin circular mini DIN