The RHE27 is an advanced function transmitter designed for rack or panel mounting in an indoor environment. Features such as API Standard Volume correction and Net Oil calculation are available.
- Measures Mass Flow, Volumetric Flow, Density and Temperature
- Outputs 2 x Analog, 2 x Frequency/Pulse, 2 x Digital Status,´
- Inputs 2 x Digital, 1 x Analog
- PC USB for RHECom, RS 485 for Modbus RTU, HART over Analog
- Optional Backlit Color LCD
- ATEX/IEC Ex, CSA approved
- Rheonik Assurance Factor®
The Standard programming package provides the following measurement and function features:
Mass flow is calculated using the Coriolis principle to provide a high accuracy Mass Flow measurement of the fluid or gas flowing through an Omega Tube Coriolis sensor.
Each Omega Tube Coriolis Sensor provides a temperature measurement from built in sensors.
The Fixed Density function allows to enter a fixed density value for volumetric flow calculations.
The Calculated Density function allows density to be generated based upon process temperature. A base/reference density at a known temperature is entered for the fluid being measured along with a coefficient describing the change in density per temperature unit. The firmware in the transmitter calculates flowing density based upon this information to use for volumetric flow calculations.
Volume measurement is calculated by dividing direct mass flow measurement by the Fixed Density.
This function calculates the volume of gas passing through the meter at standard conditions. The density of the gas at standard conditions is entered into the transmitter and the volume is calculated using this in conjunction with the flowing mass.
All setup and calibration parameters within the meter are protected with passwords to prevent unintentional or unauthorized change once installed.
The transmitter is equipped with an onboard batch controller that, in conjunction with external pumps and/or valves allows the precise delivery of a preset mass or volume of process fluid on demand. Operated from the instrument front panel, remotely via operator switches or through digital communication from a connected supervisory control system, the controller is configured to utilize either a one stage or a two stage delivery strategy in ensuring the right amount of fluid is batched through the meter. The electronics self-learns, adjusting shut off times as more and more batches are delivered to further refine the amount of delivery, saving material costs and improving quality.
Inbuilt self-monitoring functions are available that can be used to determine the reliability of the flow meter readings at all times. Diagnostics are quickly accessed through dedicated menu displays, RHECom software and the MODBUS interface.
The Density Operation Package includes all features from the Standard Operation Package plus the following measurement and function features:
The flowing density of the fluid in an Omega Tube Coriolis Sensor is determined from the measured resonant frequency of the sensor and used to calculate instantaneous volumetric flowrate.
The unit can be configured to read out in °Brix or Baume. °Brix or Baume are used extensively in the sugar and beverage industries.
Often referred to as multiphase flow, the flow regime in a partially filled pipe can cause large measurement errors and even create a measurement fault condition in a Coriolis Flow Meter. When PFPM is activated, density measurement is continuously compared to preset limits to determine if the sensor is seeing a liquid/gas mixture running through it. When multiphase flow is detected, it can be signaled, to alert users and allow action to be taken to minimize error. The full version of PFPM is available with the Assurance Diagnostics Package.
The Multifunction Package with Assurance Diagnostics Suite includes everything from the Multifunction package plus the following advanced diagnostic functions:
Assurance Factor® is a numeric value generated by an internal algorithm that in indicates the overall health of the flow meter and measurement.
Assurance Factor® value can be used to trigger changes in screen color when the optional display is fitted to the RHE (White – Amber – Blue – Red), providing highly visible wide area condition indication.
The AF advanced diagnostics package log the last 10 zero points for inspection and troubleshooting. Zero point setting is very dependent upon installation conditions and is therefore specific to each sensor in the field. Comparing zero point history can help identify installation and operation issues that could effect accuracy and performance of the flow meter.
In this full version of the PFPM function, two different monitoring methods are used, either separately or in conjunction with each other, to detect when mixed phase fluid is flowing through the Coriolis flow sensor. When the PFPM function is in operation, density measurement and/or sensor pickup voltage levels are closely monitored to determine if the sensor is seeing a liquid/gas mixture running through it. Upon detection, actions can be taken to minimize measurement inaccuracy and process disruption. The program feature also allows “bridging” an interrupted measurement (e.g. heavy gas bubbles) for up to 60 s with the last valid measurement values.
A PID controller is implemented in the transmitter to provide direct control to a valve or pump via a 4-20mA output for flow control purposes. The PID controller function features fully tunable PID parameters for either mass or volumetric flow rate. Set-point can be established via the front keypad/display or remotely via digital communication.
The fluid transfer package contains fully featured onboard data recording with a capacity to record over 500,000 time stamped records. Records include all measured variables and totalizers along with diagnostic data. Recording interval can be set from 1 to 600 seconds and recording started and stopped through the display user menu or via Modbus. Data is downloaded by request through Modbus. The RHECom software package provides a simple interface to configure the data recorder and download recorded data.
The Oil and Gas Function Package includes all features from the Assurance Factor Package plus the following advanced measurement applications:
When configured for this application, the transmitter will calculate density at standard conditions to API MPMS Chapter 11. All three product groups – crude oil, refined products and lubricants can be metered using this built-in application. Precise calculation requires temperature and pressure inputs. Both inputs can be supplied through manual user menu entries or through Modbus updates to the transmitter or the internal tube temperature of the sensor. Volume flow and totalization at standard conditions are generated using the calculated standard density value.
Crude Oil is often mixture of oil and water and it is desirable to known the actual oil content. With this function, it is possible to calculate the net oil amount in a flowing stream using a live density measurement. The standard density (at standard temperature and pressure) of both the crude oil and the water/other portions of the stream must be provided as inputs for the calculation. These can be entered manually through the transmitter’s user menu or digitally via Modbus.
Percent concentration of a fluid in a mixture of two fluids (i.e. alcohol in water) or solids in liquid can be determined using the percent concentration function. With this function, the density of both components in the stream must be provided as inputs for the calculation. These values are entered manually through the transmitter’s user menu or digitally via Modbus and should be updated as temperature conditions change to obtain the best performance.
The Custody Transfer Package includes everything from the Oil and Gas Function Package plus the following features:
For fast fill applications down to 0.5 s duration measurements, transmitter update time can be increased to 4 ms. This allows a 250 Hz totalizer update rate (50 Hz is standard) to maintain very fast tracking of actual volume/mass delivered, and e.g. through the internal batch control function, results in a maximum signal delay of 10-20 ms to a connected control valve once the batch set-point is reached. Depending upon the speed of operation of the fill valve, repeatable accuracies of better 1 % are achievable for filling operations of 500 ms duration and less.
For applications such as custody transfer where sealing is required. This switch, when engaged, prevents change of any setting within the transmitter through both the user panel interface and through a digital communications port. To accommodate some special customer needs the Lock Switch configured to leave a totalizer reset and/or a zero calibration possible.
Once the Lock Switch is set, a tamperproof seal can be applied to the transmitter case to indicate if the transmitter has not been opened since sealing.
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