AWM700 Series Mass flow sensor for gases FEATURES · Ranges 0...200 slpm1 · Actual mass flow sensing · 1...5 V output SERVICE To be used with dry gases only The AWM series is NOT designed for liquid flow and will be damaged by liquid flow through the sensor SPECIFICATIONS ELECTRICAL CONNECTION Maximum ratings Supply voltage2 8 to 15 V typ. 10 ±0.01 V Power consumption 60 mW Output load NPN (Sinking) PNP (Sourcing) 10 mA 20 mA Temperature limits Operating Storage -25 to 85°C -40 to 90°C Mechanical shock 100 g (3 drops, 3 axes) 4 3 2 1 Pin 1: Pin 2: Pin 3: Pin 4: 4 3 2 1 N/A GND +V s Vout Note: Device will be supplied with electrical connector Note: 1 SLPM denotes standard liters per minute, which is a flow measurement referenced to standard conditions of 0°C, 1 bar, 50% RH. 2 Output voltage is ratiometric to supply voltage August 2008 / 585 1/4 www.sensortechnics.com AWM700 Series Mass flow sensor for gases FLOW SENSOR CHARACTERISTICS3 VS = 10 ±0.01 V, TA = 25°C Part no. Flow range (full scale) Output voltage @ trim point AWM720P1 200 SLPM1 5.0 ±0.36 V @ 200 SLPM1 PERFORMANCE CHARACTERISTICS VS = 10 ±0.01 V, TA = 25°C Characteristics Zero offset Min. Typ. Max. Unit 0.95 1.0 1.05 V Repeatability and hysteresis (combined) ±0.5 2 ±0.30 Ratiometricity error Temperature effects Offset4 -20 to 85 °C ±0.25 Span 25 to 10 °C -2.0 25 to 40 °C 2.0 Response time Common mode pressure % reading V % reading 6.0 ms 25 p si Notes: 1 SLPM denotes standard liters per minute, which is a flow measurement referenced to standard conditions of 0°C, 1 bar, 50% RH. 2 Output voltage is ratiometric to supply voltage 3 A 5 micron filter is recommended for all devices. 4 Shift is relative to 25 °C. NOTICE: LAMINAR FLOW Due to the fast response time of the sensor, these specifications were generated using laminar flow. Airflow instability or “turbulence” present in the airstream will result in an increase in measurement uncertainty. The turbulent flow problem can be corrected by either straightening the airflow using flow laminarizing or by slowing the response of the sensor using a simple RC time constant on the output of the sensor. This, of course, slows down the sensor response time. The values needed depend on the amount of turbulence present in the application. Several techniques for laminarizing the flow include adding hex shaped honeycombs, foam, screen materials or adding constrictors (frits) to the flow stream. There are various commercial laminar flow elements that can be purchased. Unfortunately the greater the efficiency of the laminarizer, the greater the increase in pressure drop in order to establish a given flow rate. Plastic honeycomb material probably gives the most improvement for the least pressure drop. In any test fixture, the avoidance of sharp radii is an absolute requirement. 2/4 August 2008 / 585 www.sensortechnics.com AWM700 Series Mass flow sensor for gases FLOW SPECIFICATIONS VS = 10 ±0.01 V, TA = 25°C OUTPUT CURVE GAS CORRECTION FACTORS5 Gas type Helium (He) Hydrogen (H2) Argon (Ar) Nitrogen (N2) Oxygen (O2) Ai r Nitric oxide (NO) Carbon monoxide (CO) Methane (CH4) Ammonia (NH3) Nitrous oxide (N2O) Nitrogen dioxide (NO2) Carbon dioxide (CO2) Correction factor (approx.) 0.56 0.76 0.95 1.0 1.0 1.0 1.0 1.0 1.1 1.1 1.35 1.35 1.35 Notes: 5 Gas correction factors are referenced to nitrogen (N2) as calibration gas type. Approximate gas correction factors are provided as guidelines only. Individual gas types may perform differently at temperature extremes and varying flow rates. 6 When sensing Hydrogen (H2) or Helium (He) it may be necessary to power the mass flow sensor using increased supply voltage: Hydrogen typ. 12 V, Helium typ. 15 V August 2008 / 585 3/4 www.sensortechnics.com AWM700 Series Mass flow sensor for gases OUTLINE DRAWING Ø 3.6 (0.14) R 2.8 (0.11) 22.9 (0.90) 1.3 (0.05) 19.6 (0.77) Ø 22.6 (0.89) Ø 21.7 Ø 19.7 (0.85) (0.78) 22 mm (0.87 inch) medical connector per ISO 5356 36.8 (1.45) Pin 4 3 2 1 Molded-in arrow on device designates flow direction 17.3 (0.68) 22.3 (0.88) 33.8 (1.33) mass: approx. 34 g dimensions in mm (inches) ORDERING INFORMATION Flow range Dry gas 200 S LP M AWM720P1 Note: Device will be supplied with 4 pin receptacle connector (see Electrical Connection info) Sensortechnics reserves the right to make changes to any products herein. Sensortechnics does not assume any liability arising out of the application or use of any product or circuit described herein, neither does it convey any license under its patent rights nor the rights of others. 4/4 August 2008 / 585 www.sensortechnics.com