PD 340.

Home Up

 

 

INTRODUCTION  

The PD 340 flow transmitter is a precision meter for the volumetric measurement of liquids which are electrically conducting. The transmitter can be used in applications where a hygienic design is required. The rugged construction of the transmitter makes it suitable for installations where Solid particles are in the liquids. The PD 340 transmitter is equipped with a micro-processor controlling and supervising all of its functions.

 FUNCTIONS

  •  Automatic zero point correction.
  •  Unidirectional or bi-directional flow.
  •  Volumetric measurement in m 3 , litres, U.S. gallons etc.
  •  Temperature measurement using an external
  •  Temperature compensated flow measurement.
  •  Pulse output to electronic counter, 0-1000 pulses per
  • Pulse output to electromechanical counter, 0-5 pulses
  • Stop signal from internal pre-set counter.
  • Current output, 4-20 mA (extended version).
  • A display unit, PD 210, can be direct connected. The
  • PD 210 has the following features: accumulated volume, pre-selection, flowrate etc.
  • Communication capability to central data processing

 CONSTRUCTION

The PD 340 flow transmitter consists of three parts: meter head, electronic module, and terminal box. The electronic module and the terminal box are the same for all sizes of transmitters. 

The Meter head consists of a stainless metering pipe with clamp liners. Two magnet coils are mounted external to the metering pipe. Inside the metering pipe two stainless electrodes are mounted. The measuring section is designed so that changes in flow profile do not affect meter accuracy hence the transmitter has a wide range of flow rates within its linear accuracy. Changes from laminar to turbulent flow do not affect the linear accuracy and changing viscosity has no effect on meter accuracy. The calibration of the meter head is carried out using a computer controlled calibration facility.

 Fig. 1: Structure

The Electronic Module is micro-processor based and both controls the sequence of measurement and output signal transmission. The use of the micro-processor has enabled a compact design to be achieved yet including many functions. The electronic module is available in two versions, standard and extended. The standard version has two pulse outputs and can be directly connected to a display unit. In the extended version, one of the pulse outputs can be changed into analogue output, 4-20mA. Besides, it is possible to connect the transmitter to a data network for central processing.

The Terminal Box is completely separated from the electronic module. Hence connections can be changed without disruption to the electronics. All terminals in the terminal base are clearly marked with both number and function. The box is also equipped with 3 cable glands, PG 11.  

OPERATING PRINCIPLES

The meterhead consists of a metering pipe with two magnetic coils. When a current is applied to the coils a magnetic field is produced at right angles to the metering pipe. With a conductive liquid flowing through the metering pipe an electrical voltage is induced and measured by two electrodes mounted in the metering pipe. This voltage is proportional to average velocity of flow and therefore to the volume flowing. The micro-processor in the transmitter controls the current generator keeping the magnetic field constant. The voltage of the electrodes is taken via an amplifier and signal converter to the micro-processor which calculates the liquid flow.

Specifications:

 

 

 

 

 

 

 

 

 

 

 

 

Deviation flow 

measurement:-            Less than  0.3%of max.

                                     flow.

Deviation 

current output:          Cf. fig. 3, plus 0.3% of range 

                                   for current output.

Linearity:                   See fig. 3.

Repeatability:            Better than 0.5 x

                                    deviation, see fig. 3.

Ambient 

temperature effect:   Less than0.04%/10C.

 

Voltage supply effect:                     Less than 0.01%/10%.

Response time:                                0.2 sec. on pulse output, 1 sec on current output.

 

Max. capacity:                       PD 340 C 25: 8 m 3 /h.   

                                                                 C 38: 20 m 3 /h.

                                                                 C 51: 40 m 3 /h.

                                                                 C 63: 80 m 3 /h.

                                                                 C 76: 120 m 3 /h.

Measurement of temperature:     Deviation: Less than 0.9C with Pt-100 detector Din 43760.

Limits:                                            From 30C to +100C.

Ambient temperature:                   From -10C to + 50C.

Power supply:                                24 V AC 15%, 50/60 c/s or 24 V DC 15%.

Power consumption:                      Max. 6 W.

Liquid:                                            Conductivity: Min. 5mS/cm.

Temperature:                                 From 30C to +100C.

Pressure:                                        Max. 10 bar.

Outputs:                                         The transmitter can give two different output signals, pulse signal or current signal 

                                                        External voltage supplies are required for both types of signals

Pulse signals:                                 max 40V, 100mA

Current signal:                               10 - 30 V

Material:                                        Electrodes: Stainless steel AISI 316.

                                                        Metering pipe: Stainless steel AISI 316.

                                                        Coating inside metering pipe: FEP Teflon

Housing:                                         PPO Noryle

Connections:                                  Clamp pipe coupling DS/ISO 2852.

 

Approvals.                                      Compliance with EMC-directive no.: 89/336/ECC

Generic standards for emission:         Residential, commercial and light industry EN 50081-1 

                                                        Industry EN 50081-2

Generic standards for immunity:        Residential, commercial and light industry EN 50082-1 

                                                        Industry EN 50082-2

Vibration (sinusoidal):                       IEC 68-2-6 Test Fc

 

LOCATION OF TRANSMITTER

The transmitter should be located in the piping system so that the metering pipe is always filled with liquid as the transmitter can register flow even if the metering pipe is empty. As the transmitter sees air in the liquid as a volume, the volume of air in the liquid must be reduced to a minimum, and the transmitter should be located in the piping system, at the point of maximum pressure. Here the volume of the air is minimum hence the influence of air on the measurement will also be minimum. If the transmitter is located downstream of a pump which may suck air during the measuring period an air eliminator should be mounted upstream of the transmitter. The transmitter can be mounted both horizontally and vertically. Air elimination must always be guaranteed. The positive flow direction is indicated by an arrow on the meterhead.  

 

 

 

 

 

 

 

 

 

 

To create the best conditions for precise metering a straight run of at least 3x D should be mounted up- stream and downstream of the transmitter. When selecting the location of the transmitter it must be ensured that the ambient temperature is kept within the specified limits. Finally, the transmitter should be located so that the electronic box and the terminal box can be dismantled and mounted on site. The transmitter should always be electrically connected thus preventing condensation in the electronics.

OUTPUT SIGNALS 

The transmitter has three outputs, OUTPUT 1, 2, and 3. OUTPUT 1 is a power supply output, which can be used for power supply of external counter circuit. The voltage of the output can vary from 20 to 32 V DC.

OUTPUT 2 can be selected for one of three functions:

  1. 1: Pulse signal, 0-5 c/s. The signal is taken to a counter, electronic or electromechanical, for indication of the total volume, e.g. in litres.
  2. 2: Sign for OUTPUT 3. The signal indicates the flow direct- ion and can be taken to an UP/DOWN counter, which is actuated by pulses from OUTPUT 3.
  3. 3: The output signal from the pre-set counter. Before start of measuring a SET-point via the display is inserted, and the pre-set counter is reset. When the required volume is achieved, OUTPUT 2 gives a stop signal.

OUTPUT 3 can be selected for one of two functions:

  1. 1: Pulse signal 0-1000 c/s. The signal can for instance be taken to a counter for volume registration. The signal can also be used for registration of actual flow.
  2. 2: Current signal 4-20mA (only for transmitter in extended version). The signal can be taken to a regulator for controlling the liquid flow. Besides these three outputs it is possible to connect the flow transmitter direct to the display unit PD 210. It is also possible to connect the extended version transmitter to a communication system for data processing.
 

 

Home ] Up ]

Send mail to webmaster@calm-controls.co.uk with questions or comments about this web site.
Last modified: June 25, 2008