Aalborg DFM26/DFM27 is a low cost flow meter that can be ordered simply as a digital mass flow meter, or a multi parameter (flow, pressure and temperarture) digital mass meter
Multi parameter flow meters provide accurate data on three different fluid parameters:
- • Flow
- • Pressure
- • Temperature
The flow rate can be displayed in volumetric flow or mass flow engineering units for standard or actual (temperature, pressure) conditions.
Flow meters can be programmed locally by the four button keypad and LCD or remotely via RS-232/RS-485 interface. DFM flow meters support various functions including: flow totalizer, flow, temperature, pressure alarms, automatic zero adjustment, 2 relay outputs, 0-5 Vdc / 0-10 Vdc / 4-20 mA analog outputs for flow, pressure and temperature.
Interface
All features of the flow meter can be accessed via the local four button keypad and LCD. The digital interface operates via RS485 (optional RS-232 is available) and provides access to applicable internal data including: flow, temperature, pressure reading, auto zero, totalizer and alarms settings, gas table, conversion factors and engineering units selection, dynamic response compensation and linearization table adjustment. The analog interface provides 0 to 5Vdc or 0 to 10Vdc or 4 to 20 mA outputs for flow, pressure and temperature (jumper selectable).
Auto Zero
The DFM supports automatic sensor zero offset adjustment which can be activated locally via the keypad or remotely via digital interface. The auto zero feature requires absolutely no flow through the meter during auto zero process. Provisions are made to either start, read, or save the current auto zero value via digital commands.
Totalizer
The total volume of the gas is calculated by integrating the actual gas flow rate with respect to time. Both keypad menu and digital interface commands are provided to:
Set the totalizer to ZERO
- • Start the totalizer at a preset flow
- • Assign action at a preset total volume
- • Start/stop totalizing the flow
- • Read totalizer
Totalizer conditions become true, when the totalizer reading and the "Stop at Total" volumes are equal.
Flow Alarm
High and Low gas flow ALARM limits can be preprogrammed via keypad or remotely via digital interface. ALARM conditions become true when the current flow reading is equal or higher/lower than corresponding values of high and low alarm levels. Alarm action can be assigned with preset delay interval (0-3600 seconds) to activate the contact closer (separate for High and Low alarm).
Pressure Alarm
High and Low gas pressure ALARM limits can be preprogrammed via the keypad or remotely via digital interface. Pressure alarm conditions become true when the current pressure reading is equal or higher than corresponding values of high pressure alarm settings or equal or lower than corresponding values of low pressure alarm settings. Alarm action can be assigned to activate the contact closer (separate for High and Low pressure alarm).
Temperature Alarm
High and Low gas temperature ALARM limits can be preprogrammed via the keypad or remotely via digital interface. Temperature alarm conditions become true when the current temperature reading is equal or higher than corresponding values of high temperature alarm settings or equal or lower than corresponding values of low temperature alarm settings. Alarm action can be assigned to activate the contact closer (separate for High and Low temperature alarm).
Engineering Units
The measured gas flow and associated totalizer data are scaled directly in engineering units via the front panel keypad or digital interface. The following units of measure are supported: %F.S., L/min, L/h, mL/min, mL/h, scuft/h, scuft/min, lb/h, lb/min, one user defined engineering unit.
Multi-Gas Calibration
The DFM is capable of storing primary calibration data for up to 10 gases. This feature allows the same DFM to be calibrated for multiple gases while maintaining the rated accuracy on each.
Conversion Factors
Conversion factors for up to 32 gases are stored in the DFM. In addition provision is made for a user defined conversion factor. Conversion factors may be applied to any of the ten gas calibrations via keypad or digital interface commands.
Contact Closure
Two sets of dry contact relay outputs are provided to actuate user supplied equipment. These are programmable via the local keypad or digital interface such that the relays can be made to switch when a specified event occurs (e.g. when a low or high flow, pressure or temperature alarm limit is exceeded or when the totalizer reaches a specified value).
Leak Integrity
1 x 10-9 smL/sec of Helium maximum to the outside environment. DFM's are offered either as a Digital Mass Flow Meter, Model Numbers, DFM26, 36, & 46 or as a Digital Multi-Parameter Meter, Model Numbers, DFM27, 37 & 47. Model Numbers correspond to the following flow rates (based on N2) for sizing purposes:
DFM26 & DFM27: 0-10, 0-20, 0-50, 0-100, 0-200, 0-500mL/min., 0-1, 0-2, 0-5, & 0-10L/min.
DFM36 & DFM37: 0-15, 0-20, 0-30, 0-40, & 0-50L/min.
DFM46 & DFM47: 0-60, 0-80, & 0-100L/min.
There are 3 voltage (power) options:
+/-15Vdc, 12Vdc, & 24Vdc.
RS485 is standard, no cost optional RS232 is selected by changing last digit of part number from 5 to 2.
Example: DFM26S-VADL2-A5 indicates RS485, DFM26S-VADL2-A2 indicates RS-232.
1/4" compression fittings standard: DFM26, 36, 27, AND 37. 3/8" compression fittings standard on: DFM46 and 47.