The operator is responsible for assessing the suitability of Quadbeam sensors for an application, for their intended and actual use, and and for resistance of the sensor components against degradation in the environment. The manufacturer is not liable for any damages resulting from the use of the sensor beyond the cost of the sensor. Quadbeam sensors are intended for use in industrial, storm water, raw water or waste water installations for continuous monitoring of suspended solids.
Quadbeam sensors have a warranty against defects in materials and workmanship for one year from the date of shipment. During this period, Quadbeam will, at its own discretion, either repair or replace products that prove to be defective.
No warranty of fitness for a particular purpose is offered. The user assumes the entire risk of using the product. Warranty does not cover damage caused by accidental misuse, abuse, neglect, misapplication or modification. Any liability of Quadbeam Technologies Ltd is limited exclusively to the replacement of defective materials or workmanship.
Quadbeam Technologies Ltd reserves the right to make changes to this guide or the instrument without notice, as part of our policy of continued development and improvement. All care has been taken to ensure the accuracy of the information in this guide. However, we do not accept responsibility for any losses or damage resulting from errors or inaccuracies of the information in this guide.
Quadbeam uses the four-beam alternating light ratio-metric system of measurement for its sensors, which operate on 880 nm near-infrared (NIR) light.
Suspended solids sensors and turbidity sensors measure changes in light intensity to produce a relative measure of the solids or turbidity concentration in the liquid being monitored. Most commonly sold suspended solids sensors and turbidity meters use only a single beam of light, meaning that light intensity can be influenced not only by suspended solids particles but also by any solids/contamination stuck to the surface of the sensor. This is why single-beam sensors need constant cleaning. However, their measurement of light intensity can also be influenced by variations in the light source and LED as they age.
Multi-beam sensors measure light intensity across multiple light paths. Quadbeam sensors combine these measurements in a ratio using mathematical algorithms. This ratio automatically compensates for contamination stuck to the surface of the sensor and for variation in the sensor's light components, making Quadbeam sensors more accurate and reliable than single-beam sensors. That's why multi-beam sensors are often used in process control installations where a repeatable output is very important.
Signal drifts as sensor ages or gets contaminated
Algorithm compensates for contamination and ageing giving very repeatable signals
Example application: measures 0-40% milk fat. 2" Triclover fitting.
Example application: measures 0-40% milk fat. 3" Triclover fitting.
Example concentration: 0-25 g/L SiO2. Applications include return and waste-activated sludge measurement, clarifier monitoring.
Operates to 105°C. Example application: CIP optimisation, measures 0-40% milk fat. 3" Triclover fitting.
Example application: measures 0-20% milk fat. 3" Triclover fitting.
Example concentration: 0-10 g/L SiO2. Applications include Loss Monitoring, Clarifier monitoring and control.
Example application: measures 0-20% milk fat. To fit Type N Varinline access unit.
Operates to 105°C. Example application: CIP optimisation, measures 0-20% milk fat. 3" Triclover fitting.
Example application: measures 0-1.5% milk fat. 3" Triclover fitting.
Example concentration: 0-2.5 g/L SiO2. Applications include filtration monitoring, clarifier monitoring.
Example application: measures 0-1.5% milk fat. To fit Type N Varinline access unit.
Example application: measures 0-50 to 0-1000 NTU. 3" Triclover fitting.
Quadbeam sensors typically only need occasional cleaning at most because their multi-beam technology self-compensates for accumulated contamination. However, in applications where extra cleaning is required, a cleaning guard connected to a hose supplying an occasional burst of compressed air or water can be fitted.
Hygienic pipe installation
Quadbeam hygienic sensors come in HY and VN configurations. All 3HY sensors fit the standard 3” tri-clamp fitting.
The S10-2HY fits a standard 2” tri-clamp fitting.
The VN sensors fit the GEA Varinline® Type N access unit.
The sensors work by measuring the change in light intensity. Therefore anything that can reflect, deflect or absorb the light will affect the output of the sensor.
Keep a "Clear Zone"
To reduce the chance of light reflection off walls of flumes, tanks, channels, sumps etc, it is recommended where possible to have a “Clear Zone” from all objects of at least 50mm (2”). Ensure that the sensor is fixed in place. The thread at the back of the immersion-style sensor is 1 1/4" NPT and will fit many standard 32mm plastic fittings.
Things that can change the reflected or absorbed light, and therefore affect the output of the sensor include:
There are three main issues to consider for drain installations:
1. make sure that the drain is always full so that the end of the sensor - the "fingers" - is always immersed in the solution. Failure to do so could result in unpredictable readings;
2. keep ambient light constant in order to avoid variations in reading between day and night. If the drain or flume is open to the atmosphere, protection from sunlight will reduce the chance of abnormal readings produced by scattered or direct sunlight;
3. place the sensor in a position with the lowest possibility of foam or bubbles (e.g. caused by turbulence), as they can affect readings.
The vertical mount is most common as it can be implemented in shallow channels. A horizontal mount is used in covered drains where it is not possible to implement a vertical mount (described in the next section). An immersion-style sensor should be used for drain installations.
In this vertical mount, a pipe is attached to the 1 3⁄4 inch thread at the back of the sensor. This pipe is then fixed to the drain by pipe clamps. For T30 sensors, which have a bigger body than the S-series sensors, the pipe clamps could be mounted directly on to the sensor. Care must be taken to avoid over-tightening the clamps and possibly damaging the sensor.
For S-series sensors, if the flow in the channel is not deep enough, a longitudinal hole can be created to ensure that the sensor fingers are continuously immersed, with the recommended Clear Zone.
A vertical mount is not possible in some cases, for example in covered drains. In these situations the sensor can be mounted horizontally along the flow. It should be mounted using the 1 1⁄4 inch thread with a short pipe that connects to an elbow typically having a 90° angle. The other end of the elbow connects to a longer pipe which is mounted with pipe clamps.
Dimensions (A) and (B) should be 50mm (2”) for S-series sensors, and 75mm (3”) for T-series sensors to provide a “Clear Zone”. Dimension (C) should be at least 50mm (4”) for both series.
In this set-up, the minimum channel depth is 150mm (6”) for S-series sensors and 175mm (7”) for T-series sensors.
The sensor should be installed such that the two IR transmitters (black-looking ) are at the bottom facing upwards and the two IR receivers are at the top facing downwards. This minimizes interference from ambient light changes. The front of the sensor should be facing downstream.
This installation is set up with an immersion-style sensor. The thread at the back of the sensor is used to mount it at the end of a pipe. This pipe is fixed to the side of the tank wall using clamps as shown. Ensure the clamps push the sensor far enough away from the wall to maintain the Clear Zone. It is recommended that the sensor is installed approximately half-way down the tank. If the tank is shallow, it is preferable that the sensor is closer to the bottom rather than the top, to avoid the effect of ambient light changes.
It is also recommended to install an elbow in the pipe as shown, to push the sensor away from the wall and closer to the centre of the tank.
If the tank or sump is open to the atmosphere, protection from sunlight will reduce the chance of abnormal readings produced by scattered or direct sunlight.
In loss monitoring installations in dairy plants where there are multiple points of measure, for example conductivity, pH and temperature as well as suspended solids or turbidity, it can be advantageous to run the monitored fluid through an instrument manifold.
Quadbeam sensors have a very repeatable output because they use the four-beam, ratio-metric principle. Therefore, the more care that is taken in setting up the sensors, the more accurate the output will be. The output is only as good as the quality of the calibration and installation.
Comprehensive instructions for the MXD73 and MXD75 transmitters are available in manuals at www.quadbeam.com/support.
Relative measurement - Probe Signal (PS)
In the linearisation process, the probe signal (PS) value is related to concentrations of suspended solids in the solution being used for calibration. The PS is a binary number generated by the input card that has an “engineering” value applied to it in the transmitter “lineariser”. The PS is the result of the four-beam ratio-metric output, meaning it is the repeatable part of the process. The sensors are analogue or have an analogue component which means each sensor/input card combination will be a little different.
The sensors measure the intensity of NIR light emitted across the sensor light paths. Different materials absorb or scatter NIR light in different ways. For best results, where possible, use the actual process fluid and solids being measured as standards to set up the linearisation of the sensors.
It is not uncommon for pre-prepared solutions to be used, for example NTU solutions or varying concentrations of SiO2 in water. These work very well as repeatable standards, but installers should ask whether they are directly relevant to what is being measured and are understood by operators?
It is possible to have up to 10 points in a calibration curve. Some materials have a linear response to 880 nm NIR, for example NTU solutions and SiO2. Some materials have a non-linear response, for example milk fat. In non-linear applications like milk fat monitoring we recommend calibrating at least 5 points on the curve. Where relatively tight control is required we recommend clustering the calibration points around the control range.
After preparing your samples, work through the following menu steps:
When ready for actual curve set-up, place the sensor in opaque cups ensuring the bottom of the sensor fingers are at least 20mm from the bottom of the cup and the sensor is centralised. Complete the following steps:
Repeat for each point on the calibration curve.
Because of the variance between inline measurement and calibration cups, it is possible to do a fine adjustment after the sensor has been installed.
1. Once installed, take a grab sample at the same time as reading the sensor output.
2. Analyse the sample in the lab.
3. If required to bring into line with the lab reading, move the zero point of offset by working through the calibration menu accessed from the main menu.
To help eliminate variability in the set-up, build a set of calibration vessels as close as practical to the actual pipe work.
Work through the same steps as above.
Best calibration (for tight control applications)
For applications involving tight control, for example fat standardising or yogurt concentration control, install the sensor with a sample port as soon after the sensor as practical.
Take a sample during operation, and at the same time note down the PS value showing on the MXD transmitter.
Vary the operation to change the solids concentration, take another sample and record the PS value again.
Repeat at least five times with varying solids concentrations.
Have the lab analyse the samples and provide the solids concentration. It is often useful to have the lab run “same sample” tests to ensure lab-repeatable testing.
When the solids concentration is established from the lab, go back to the MXD transmitter and manually input the concentration values against the PS values recorded at the time of sample extraction.
Please note that higher concentration samples should have a higher PS value than lower concentration samples.
It can help to add an input filter for installations where the data is changing rapidly.
The life of the sensor can be extended by activating CIP mode to turn off the sensor head if it is not being used for measuring the hot processes during CIP.
After setting up the three curves, saving two of them to separate stores and assigning two digital inputs to those stores, you will be able to switch between them.
With no digital inputs you will be in a neutral position so the active curve will operate.
Activate Digital input assigned to store A will switch set-up to store A.
Activate Digital input assigned to store B will switch setup to store B.
You always have to go back to neutral before switching from A to B.
Curve set-up A
Set-up the channel, curve and outputs in the normal way.
From the main menu go to: SAVE/RESTORE
Curve set up B
Repeat the process for channel, curve and cutput set-up B, but this time save in SAVE B.
Curve set-up neutral
For your third curve, set-up the curve and output in the normal way. Do not save. For security you can back-up the whole unit to an SD card.
For curve A
From the main menu go to digital inputs:
Select the input:
Select the channel
Set function to Switch Channel
Set Store to Store A
For curve B
Repeat the process for Digital Input 2 and Store B.
For curve neutral
No digital input activated. Set up the curve in the normal way, do not save.
Connect digital inputs.
To select curve A, activate Digital Input 1.
To select curve B, activate Digital Input 2.
To select curve neutral - do not activate Digital Input 1 or 2.