Download Warranty

Fluorescent
Probe
(4 – 20 mA)
Version 1.0
January 21, 2008
P/N:
TURNER DESIGNS
845 W. Maude Ave.
Sunnyvale, CA 94085
Phone: (877) 316-8049
(408) 749-0994
FAX:
(408) 749-0998
Table of Contents
Table of Contents ........................................................................................................................................... 2
Introduction .................................................................................................................................................... 3
Description ................................................................................................................................................. 3
Inspection and Setup ................................................................................................................................... 3
Installation and Operation .............................................................................................................................. 4
Installing the Fluorescent Probe ................................................................................................................. 4
Operation .................................................................................................................................................... 4
Calibration and Calculations .......................................................................................................................... 5
Calibration .................................................................................................................................................. 5
Calculating Calibration Coefficients .......................................................................................................... 6
Recommended Measurement Practices .......................................................................................................... 7
Distance and Surface Considerations ......................................................................................................... 7
Minimizing Variations in Signal ................................................................................................................ 7
Linear Range and Quenching ..................................................................................................................... 7
Temperature Considerations ....................................................................................................................... 8
Warranty ......................................................................................................................................................... 9
Terms .......................................................................................................................................................... 9
Warranty Service ........................................................................................................................................ 9
Out of Warranty Service ............................................................................................................................. 9
Appendix A ...................................................................................................................................................10
Fluorescent Probe Specifications ...............................................................................................................10
Appendix B....................................................................................................................................................11
Fluorescent Probe Wiring Table ................................................................................................................11
2
Introduction
Description
Turner Designs’ Fluorescent Probe is an accurate, single channel fluorometer designed to measure and
provide an output signal proportional to the concentration of a fluorescent dye. In a representative
application, the Fluorescent Probe will be used with a data collection system to monitor and control the
level of treatment chemicals in industrial applications.
The fluorescent tracer dye is measured by passing the water containing the dye/chemical past the
Fluorescent Probe’s optical window. An excitation light source illuminates the solution, and excites the
dye in the solution, which fluoresces at a different wavelength. The intensity of the emitted light is
proportional to the concentration of the dye in the system.
Turner Designs’ Fluorescent Probe has a low maintenance design that will provide trouble-free
performance.
Inspection and Setup
4 and 20 mA
Trimpots
Cable with 4 bare leads for
connecting to power and mA
output (See Appendix B for wire
functions)
Optical head
3
Installation and Operation
Installing the Fluorescent Probe
Turner Designs’ Fluorescent Probe is rated for light industrial environments.
Do not install the Fluorescent Probe:



within 10feet (3meters) of devices that produce a strong electromagnetic field, such as large generators
in direct sunlight or near heat sources (maximum environment temperature is 120F/49C)
on Vibrating walls or surfaces
NOTE: air trapped on the optical window will influence signal
Operation
Turner Designs’ Fluorescent Probe uses a Light Emitting Diode (LED) at a specific wavelength to excite
the fluorophore of interest in samples or solutions. Upon excitation, the fluorophore emits a different
wavelength of light (fluorescence) that will be detected by the unit’s photodiode.
After power (11-13 VDC) is applied power to the Fluorescent Probe, allow 5 seconds for the LED to
stabilize. After LED has stabilized, measurements can be taken as continuous current output of 4 – 20 mA.
See page 6 for recommended positioning of the Fluorescent Probe’s optical head and other measurement
practices.
4
Calibration and Calculations
Calibration
1.
Connect the Fluorescent Probe to the power supply and digital multimeter as shown below
Multimeter
BROWN
DC Power
Supply
12 VDC 0.2 A
ORANGE
+
-
RED
20 mA
BLACK
A
Common
2.
Submerge the optical head in a sample of de-ionized (DI) water (figure 2)
3.
Use a screwdriver to adjust the trimpot marked 4mA so that the multimeter reads 4mA
Multimeter
4 mA
ORANGE
BROWN
20 mA
Flathead
Screwdriver
4.
A
Common
Take the unit out of the de-ionized water sample and submerge it in a sample with known
concentration (e.g. 30ppb).
5
5.
Use a screwdriver to adjust the trimpot marked 20mA so that the multimeter reads 19mA
Multimeter
19 mA
ORANGE
BROWN
20 mA
A
Common
Flathead
Screwdriver
The data collected upon completing these calibration steps can be put into a table similar to table 1.
Solution Measured
Blank Solution
Sample Solution
Concentration
Multimeter current output
0 ppb (DI)
30 ppb
4 mA
19 mA
Table 1
Example of data collected
from calibration steps 1-5
Calculating Calibration Coefficients
With the data collected you can find the coefficients required for calculating concentrations using the
equation:
y = mx + c
(Equation 1)
Where, “y” is the sample concentration
“m” is the slope of your equation
“x” is the sensor output in mA
“c” is a constant equal to “y” when x = 0
1.
2.
3.
Finding the slope of your equation using 30ppb standard concentration:
m = [(30 - 0) / (19 - 4)] = 30/15 = 2
(Equation 2)
0 = [(m * 4) – c], c = -8
(Equation 3)
Finding the c constant:
Substitute “m” and “c” from Equation 1 with end values from Equations 2 and 3 :
y = 2x – 8
(Equation 4)
6
You can now calculate “y” (ppb) concentrations simply by substituting (mA) values for “x” in equation 4.
Recommended Measurement Practices
Distance and Surface Considerations
When calibrating or taking measurements, position the Fluorescent Probe as shown in figure 1.
NOTE:
 The minimum distance the optical head should be from the bottom is 3 inches
 The minimum distance the optical head should be from the adjacent surfaces is 2 inches (all around)
 The type of sample holder to be used if sample holders are necessary is glass
 The optical head should be free from air bubble because they will interfere with measurements
>2 inches
all around
Glass
Beaker
>3 inches
No Air Bubbles
On Optical
Surface
Dark/Black NonReflective Surface
Figure 1
Minimizing Variations in Signal
Turner Designs’ Fluorescent Probe has a flat surfaced optical window that might trap air bubbles when
submersed in water. Gently run your finger over the optical window to free all trapped air bubbles, as they
will interfere with measurements.
Linear Range and Quenching
The Fluorescent Probe’s linear range begins with the smallest detectable concentration and spans to an
upper limit (concentration) that is defined by a directly proportional relationship between concentration and
fluorescence. The directly proportional relationship is dependent on:


the properties of the fluorescent material
the filters used
7

the light’s path length through the sample
A non-linear relationship is seen at high concentrations where the fluorescence signal is not proportional to
concentration, see Figure 6 below. “Signal quenching” refers to the decrease of fluorescence as
concentrations continue to increase.
Fluorometer
Reading
Fluorometer Response Curve
Sample
Quenching Region
Sample
Linear Region
Figure 2
Graph showing Linear and
Quenching Regions of the
sample’s response
Sample Concentration
You can check linearity by diluting a sample 1:1, or some other convenient ratio. If the sample is still in
the linear range, the reading will decrease in direct proportion to the dilution. If the reading does not
decrease in direct proportion to the dilution, or if the reading increases, the sample is beyond the linear
range of the fluorophore.
Temperature Considerations
Fluorescence is temperature sensitive and depends on the dye or fluorophore of interest. As the
temperature of the sample increases, the fluorescence decreases. For greatest accuracy, determine the
temperature coefficient of the dye or fluorophore being used, record the sample temperature, and correct
the sensor output for changes in temperature. See Table 2 for examples of temperature compensation
coefficients. Information on how to apply these corrections is included in the Turner Designs Application
Note: A Practical Guide to Flow Measurements,
(http://www.turnerdesigns.com/t2/doc/appnotes/998_5000.html)
Dye
Correction (/oC)
Correction (/oF)
Rhodamine WT
-0.026
-0.0144
Fluorescein
-0.0036
-0.0020
Table 2
Examples of Temperature
Corrections for two common
fluorescent dyes
8
Warranty
Terms
Turner Designs’ Fluorescent Probes and accessories are free from defects in materials and workmanship
under normal use for a period of 12 months from the instrument’s ship date as warranted by Turner
Designs.
Warranty restrictions:
 Instruments and accessories must be installed, powered, and operated as described in this users
manual or additional instructions provided
 Damage incurred while shipping is not covered
Warranty Service
If instruments or accessories require service while under warranty and you are a customer in the contiguous
continental United States:
1.
2.
3.
Write ([email protected]) or call (877) 316-8049 the Turner Designs Technical Support
Department
Describe the nature of the problem
Perform minor adjustments/tests as suggested by the Technical Support Department
If the Technical Support Department cannot correct the problem, an RMA number will be issued to the
customer and the instrument can be shipped prepaid to Turner Designs with a statement of shipping
charges. The instrument will be repaired and returned with a check to cover all shipping costs.
Customers outside the contiguous continental United States:
If you purchased our equipment from an authorized distributor, you must contact the distributor. If you
purchased direct, contact Turner Designs. If Technical Support cannot correct the problem, we will repair
the instrument at no charge. However, you will be billed for shipping, documentation, and other charges
accrued during the return process.
NOTE: An RMA number is required for all returns. This ensures:



The problem you described was properly noted
The instrument or accessory needs to be returned to Turner Designs for repair
The turnaround time for the repair is rapid and cost efficient
Out of Warranty Service
Our Technical Support Department can assist you by phone or email at no charge. Repair service will be
billed on a fixed price basis, plus any applicable duties and/or taxes. Your bill will include return shipment
freight charges.
Address for Shipment:
Turner Designs
845 W. Maude Ave.
Sunnyvale, CA 94085
Toll Free: (877) 316-8049
9
Appendix A
Fluorescent Probe Specifications
Parameter
Specification
Linearity (over dynamic range)
0.99 r2
Power Draw
0.2 A @ 12 VDC
Input Voltage
11 – 13 VDC
Signal Output
4 – 20 mA
Light Source
Light Emitting Diode
Detector
Photodiode
Warm up time
5 seconds
Dimensions
Length: 5.26 in
Diameter (optical head): 0.874 in
Diameter (base): 1.99 in
Weight
126 grams
10
Appendix B
Fluorescent Probe Wiring Table
Probe Wire
Function
Connection
Red
Supply Voltage
11 – 13 VDC
PSU – Positive Connection
Black
Supply Ground
0 VDC
PSU – Ground Connection
Orange
Signal out to data logger,
“A”, 4 – 20 mA DC
Multimeter “A” Connection
Green/Brown
Signal out to data logger,
“Common”, 4 – 20 mA DC
Multimeter “Common” Connection
11