THE ULTIMATE MONITOR FOR TOTAL MOISTURE CONTROL

Located normally in a control panel, the Hydro-View unit displays both the instantaneous and batch average moisture contents from any one of the Hydronix moisture sensors. The unit may be used as a stand alone system for display purposes or for upward interfacing with a batch controller to provide dynamic batch weight correction.

Available in both panel and wall mounting configurations.

Other facilities include:

Precise digital technique for calibrating the sensor

Graphic display of the sensor signal and other parameters

Linear 4-20mA/0-10Vdc output with programmable ranges

Other facilities include:

Two 'set point' relay outputs

RS232 serial port for data logging

Optional RS485 port for networking

Operation in (currently) twelve languages

Either the instantaneous or the average percentage moisture is displayed in large figures. If the averaging facility is being used (by means of the average/hold input) then this figure is displayed in large characters and the instantaneous or 'now' figure is displayed simultaneously in the small box.

SIGNAL
CONDITIONING

The Hydro-View incorporates a technique that ensures optimum smoothing of the sensor signal yet without sacrificing the ability to respond quickly when monitoring changes in process moisture contents. This is particularly relevant for mixer and conveyor belt applications.

All signal conditioning parameters are selectable by means of the keypad and therefore it is possible to tune the system for optimum response in any particular application. The trend display enables the precise effect of the signal conditioning to be observed in graphical form. Two sets of signal conditioning parameters may be selected by a digital input.

INSTANTANEOUS
MOISTURE READING

The signal bandwidth of the instantaneous moisture reading may be controlled by the adjustment of a digital filter.

The Hydro-View will update the instantaneous moisture reading 10 times per second but this value may be smoothed by using the mean value over the most recent 1 to 1000 samples, according to the requirements of the application and bandwidth capabilities of upstream instrumentation.

BATCH AVERAGE
MOISTURE READING

In Ready-Mix batching applications, it would be normal to compute the average moisture content over a batch of materials and use this to adjust the weight of material.

Using an 'average/hold' digital input to the Hydro-View, it is possible to begin averaging at the start of a batch (using the then instantaneous reading) and then to output the continuously changing average moisture reading during the batch. An upstream batch control system will then use this value to dynamically recompute the batch target weight so that the final delivered dry weight of material is correct.

On removing the average/hold signal, the average value is retained by the Hydro-View until the start of the next batch.

On many large batching plants, it is necessary to delivery a material from several bins simultaneously in order to meet the throughput requirements of the plant. In such cases, the moisture content from the different bins will generally be quite different and simultaneous measurement across several bins becomes necessary. Unfortunately, most popular batch computers will only allow you to use a single moisture value for a given material.

The Hydro-View solves this problem very neatly. Using its RS232 ports to connect two Hydro-Views together, the average value across two bins may be computed and delivered to the output of one of the Hydro-Views which is configured as a Master unit. All you need to do this is a simple cross-over cable to connect the Hydro-View units together.

The technique may be extended to up to four bins using RS485. In this case, a small module is inserted in each Hydro-View and the units connected together using a twisted pair cable. In both cases, the connected systems will compute an average value using only those bins which are currently batching and excluding values from any bins which run empty during the batch.

CALIBRATION

Calibration of the sensor is performed remotely using the Hydro-View and therefore, unlike other systems, there should never be a need to make adjustments to the sensor to calibrate for different materials.

The output from the sensor is calibrated using two different laboratory moisture measurements for the material concerned, together with the associated unscaled sensor input reading observed on the Hydro-View display at the time of taking the samples. These two pairs of values are inserted into the calibration table, which "fixes" the calibration line for the material concerned.

Calibration lines for up to 10 different materials may be selected either from the keypad, or remotely via one of the serial ports. It is also possible to select from up to four materials using the digital inputs and outputs available on the Hydro-View.

TREND DISPLAY

A unique facility of the Hydro-View is the 'Trend Display' which will graphically chart the following four functions:

Raw sensor input voltage (V)

Sensor voltage after conditioning (Vc)

Instantaneous Moisture % (M)

Average Moisture % (A)

Although only one trace can be displayed at any one time, all four values are recorded simultaneously and any of the four traces may be selected. It is therefore possible to compare for example the raw sensor input voltage trace to the conditioned signal to assess the effectiveness of the signal conditioning parameters selected.

A TYPICAL HYDRONIX INSTALLATION

The figure right shows a typical wet-batching system using Hydro-Probes, Hydro-Mix and Hydro-View units. A dry-batch plant would not employ the Hydro-Mix sensor due to the short mixing time involved.

The scheme shows the outputs of the Hydro-Views linked directly to the batch controller - this may be using either analogue (4-20mA or 0-10V) signals or RS232. Alternatively, RS485 might be used to connect the units back to the batch controller using a single twisted pair cable, depending on batch controller capabilities. Click here for typical connection schematics.

HYDRO-VIEW SYSTEM COMPONENTS

Steel case with aluminium fascia.

Fascia dimensions:
144x96mm. Panel cut out size 140x92mm.

Depth of unit 180mm. (250mm with cables).

The Hydro-View is supplied as standard with an RS232 serial port. The optional RS485 module allows up to 32 Hydro-View units to be connected to a suitable host computer using a single twisted pair cable, or allows use described under Group Averaging . Simultaneous independent use with standard RS232 port is allowed.

Connects a Hydro-View to an IBM-Compatible PC. Converts a 6-way RJ style connector to 9-pin D-type plug via a 3m cable.

Connects two Hydro-View units to allow the mean value of two moisture sensors to be computed as described under Group Averaging.

TECHNICAL SUMMARY

Membrane keypad with polyester overlay.