Jim ‘Slim’ Mimlitz, SCADAmetrics
Venturi-Type Flow Meters are utilized within the municipal water industry to measure flows both within the water treatment plant, as well as within distribution. The Venturi flow measurement is based upon measuring the pressure drop between two sections of the tube with differing diameters. Often times, Venturi meters are outfitted with only a 4-20 milliamp flow rate signal output, yet the owner may benefit from monitoring totalization as well.
In order to totalize the flow, a discrete integral must be calculated of the 4-20mA flow signal, with respect to time. Programmable Logic Controllers (PLC’s) are capable of performing such an integral, and are often utilized to this effect. However, SCADAmetrics is pleased to introduce a simplified, hardware-only solution, based on our new device: the model MTP “Milliamp-to-Pulse Converter”.
The model MTP monitors the 4-20 milliamp rate-of-flow signal from a 4-20mA flow meter, and emits a pulse output, where each pulse represents a fixed volume of water. This pulse may then be accumulated within an EtherMeter, which in turn can report the totalization to a connected SCADA system, a connected AMI system, or both.
It is important to stress that the MTP/EtherMeter combination is suitable for any flow meter which is equipped with a 4-20mA output only. Other types may include certain Vortex meters, magnetic flow meters, etc…
After integration of such a system, if used for custody-transfer and/or billing applications, it is incumbent upon the user to determine the accuracy of the overall system and perform calibration adjustments, as necessary.
Illustration: Venturi-to-SCADA Connection:
Illustration: Venturi-to-SCADA and AMI Connection:
SCADA Connection
The EtherMeter provides a robust SCADA connection, as it can transmit both totalization and rate-of-flow using modern industrial Ethernet protocols, such as Modbus/TCP and Allen-Bradley EtherNet/IP. It may also transmit the metering data using modern industrial Serial protocols, such as Modbus/RTU and Allen-Bradley DF1.
AMI Connection
When a SCADAmetrics model MBE Encodalizer is added to the system, the totalization may be transmitted to an AMI endpoint, such as those offered by Neptune, Master Meter, Metron-Farnier, Honeywell, Mueller Systems, Zenner, Sensus, Badger, Itron, Kamstrup, and others…
The MBE Encodalizer outputs an industry-standard, 3-wire encoded signal formatted as either Neptune-protocol or Sensus-protocol (user-selectable via dip switches).
Additional in-depth procedures may be studied within SCADAmetrics Application Note #34 (PDF).
Want to Learn More?…
Are you interested in learning more about how SCADAmetrics flow instrumentation, when paired with a 4-20 milliamp-only flow meter, can provide a wealth of value-added SCADA and AMI options? Give us a call!… We’ll be glad to discuss the details!