415 Steam and Gas Flow Computer by Contrec

415 Flow Computer by Contrect for Gas & SteamContrec's 415 Steam and Gas Flow Computer incorporates the following compensation equations for gas and vapours:

Ideal Gas Law using temperature and pressure correction, but where compressibility correction is not required.

General Gases where compressibility is calculated using the Redlich-Kwong¹ state equation. This equation is suitable for gases which have known properties, and information on common industrial gases is provided in the operating manual.

Natural Gas using the NX-19² equation to calculate super compressibility.

Steam Equations for both saturated and superheated steam. Mass and energy flow rates are calculated using standard equations to determine the specific weight and enthalpy of steam.

Programming is simplified with the 415's backlit alphanumeric display providing a clear indication of all parameters, as well as engineering units. The 415 is fully programmable and all operating parameters are entered via the front panel keypad. This instrument is available with direct RTD input (415R) or with 4-20mA temperature input (415A). Both accept a 4-20mA pressure input. Inputs from a wide range of flowmeters are accepted, including vortex, turbine, orifice plate, averaging pitot tubes, wedges and target flowmeters. Where two differential pressure transmitters are used across an orifice or similar device, to increase the measured flow range, both DP transmitter inputs are accepted and scaled separately with automatic crossover.

Flowmeter Inputs
Parameters Displayed

  • Displays mass flow, corrected volume and energy flow
  • Accepts 4-20mA and frequency flow inputs
  • Temperature and pressure compensation
  • Dual ranged DP transmitter inputs
  • Operates from 14-28V dc or ac mains
  • Simplified programming
  • Data logging output

GENERAL SPECIFICATIONS     Display 2 line x 20 character (5.5mm high) alphanumeric backlit LCD.
Keypad Sealed membrane keypad with four keys.
  • Transducer Supply Requiements - 8-24V dc field adjustable, 65mA max
  • dc supply - 14 to 28V dc, 300mA typical (no options)
  • ac supply - ac mains set internally to 95-135V ac or 190-260V ac

0 to 55°C

Sealing IP65 (Nema 4X) watertight
APPROVALS   Electrical ETL (US) approved to UL508 and CSA
Interface CE Compliance
Enclosure CENELEC, FM, CSA and SAA approved enclosures available for hazardous areas
Frequency Input    Range
  • Miniumum: 0.25Hz on Rate, 0Hz on Total
  • Maximum: 10KHz
Input Circuits Accepts most sine, logic and proximity switch inputs
K-factor Range 0.1000 to 999,999
Non-Linear Correction Up to 10 correction points
4-20mA Inputs       Input Types Flow (2 ranges), pressure and temperature
Input Impedance 250 ohms
Measurement Range
  • Pressure: 0 kPa abs (0 psia) to 100,000 kPa abs (10,000 psia)
  • Temperature: -273°C to 1200°C
Span (flow) 999,999
Accuracy 0.05%
Circuit 250 ohm resistors connected to a common signal ground (current sinking) 
Non-Linear Correction A 20 point curve can be applied to the flow input
RTD Input (Model 415R)    Type Platinum PT100
Range -100°C (-l48°F) to 200°C (392°F). (Note a wider temperature range can be handled via a 4-20mA input.)
Accuracy 0.1°C
Linearity The non-linearity of the RTD is internally compensated for
Pressure Input   Type Absolute or gauge
Span Absolute or gauge pressure is programmable at 4mA and 20mA
Atmospheric If a gauge pressure sensor is used, the atmospheric pressure is programmable
Pulse Output   Pulse Width l0ms (negative going pulse).
Duty Cycle 49 pulses/sec max
Output Open collector transistor will sink l00mA max. (Note: Suitable for driving remote counters or PLC's.)
RS232/422 Option         Type Both RS232 and RS422 are provided. (Note: When using the RS422, multi-point communication (RS485) can be implemented with up to 32 instruments connected to a common bus.)
Function Printer and computer protocols are fully programmable.
Printer A print is initiated on each reset or at a programmable time interval. (Note: Protocols are provided for roll & column printers.)
Computer An ASCII based protocol enables all displayed parameters to be read and the totals to be reset
Baud rate 300 to 9600
Data Bits 7 or 8
Parity None, Odd or Even
Data Logging Output generated at intervals of once a minute to once every 24 hours. The totals can be programmed to reset on each print or at 24:00 hours.
Time A real time clock is provided to give time and date on each output
4-20mA Output Option     Function Outputs flow rate in mass, corrected volume or energy. The 4 and 20mA points can be programmed to provide a fully scaled output.
Resolution 10 bits
Accuracy Better than 0.1%
Maximum Load 500 ohms internally powered. 950 ohms from external 24V dc
Isolation Output is isolated
Relay Output Option Function High and low flow rate alarms based on the flow rate in mass, corrected volume or energy.
Maximum Ratings
Power: 250VA.
Voltage: 250V ac, 30V dc.
Current: 5 Amps.
Ideal Gas
  • Corrected Volume: m³ or ft³
  • Mass: kg or lbs
Temp Range -273°C to 800°C
Pressure Range 0 kPa abs (0 psia) to 100,000 kPa abs (10,000 psia)
General Gas Gases Handles most gases for which the critical temperature, pressure and specific gravity are known
Compressibility Calculated using the Redlich-Kwong equation
Temp Range -273°C to 800°C (RTD has a more limited range)
Pressure Range 0 kPa abs (0 psia) to 100,000 kPa abs (10,000 psia)
Natural Gas Calculations Uses NX-19 equation to calculate super compressibility FPV
Temp Range -40°C (-40°F) to 115°C (240°F)
Pressure Range 101.325 kPa abs (14.69 psia) to 34,380 kPa abs (4985 psia).
Specific Gravity Range 0.554 to 1.000
Carbon Dioxide 0 to 15% mole
Nitrogen 0 to 15% mole
Steam Calculations Uses 1967 IFC Formulation (ASME) equations to calculate specific weight and enthalpy of steam.
Types Saturated and Superheated.
Temp Range 20°C to 800°C  (RTD has a more limited range.)
Pressure Range 1 kPa abs (1 psia) to 100,000 kPa abs (10,000 psia).
Saturated Steam When measuring saturated steam, it is possible to omit either the pressure or temperature sensor since, on the saturated line, there is a corresponding pressure for all temperatures.

1 Redlich & Kwong, "An equation of State", Chem Rev., vol 44, p233, 1949.
2 Par Research Project NX-19. "Extension of Range of Super Compressibility Tables", American Gas Association, 1962.

Important: Specifications are subject to change without notice. 

The 415 accepts most flowmeter inputs including:

  • Frequency producing flowmeters such as vortex, turbine or positive displacement.
  • Volumetric flowmeters with 4-20mA outputs such as vortex or turbines with a frequency to current converter on the output.
  • Differential Pressure devices such as orifice plates, averaging pitot tubes, wedges, cones, elbows or target flowmeters, where a square law relationship applies.
  • Linear Differential Pressure devices where the 4-20mA output is directly proportional to the flow rate.
  • Dual Range (Stacked) Differential Pressure Transmitters where two separately spanned transmitters are used across a common flow device such as an orifice (both square and linear inputs).
  • Non-Linear Differential Pressure devices such as laminar flow tubes or VA meters. A 20 point correction curve can be programmed to compensate for any non-linearities in the flowmeter.

Information is displayed in a number of windows which can be selected using the DISPLAY key.


Flow rate of the mass, corrected volume or energy is displayed in units per day, hour, minute or second.
Total of the mass, corrected volume or energy. A reset key on the front panel enables totals to be reset, or the key can be disabled during setup. Totals are displayed with 8 digits.

Gas Flow

Corrected volume at base conditions (m³ or ft³)
Mass (kg or lbs)
Temperature (°C or °F)
Pressure (kPa or psi) in absolute or gauge
Compressibility Z, for general gases
Super compressibility Fpv for natural gas

Steam Flow

Mass (kg or lbs)
Energy (MJ or Btu x 1000)
Temperature (°C or °F)
Pressure (kPa or psi) in absolute or gauge 3
Specific weight in dm /kg
Specific enthalpy in kJ/kg

415 Flow Computer by Contrec Dimensions

DOWNLOAD  415 Flow Computer Data Sheet 

DOWNLOAD  415 Flow Computer Operation Manual