FCML 412 Analog Chlorine Sensors
Specifications:
- Product Name: FCML 412 N, FCML 412 M12
- Product Type: pH-independent sensor for free chlorine
- Origin: Printed in Germany
Product Usage Instructions:
1. Safety
Ensure to follow all safety guidelines provided in the operating
manual.
2. Commissioning
3.1 Scope of delivery: Check if all components
are present as per the list in the manual.
3.2 Filling the membrane cap with electrolyte
solution: Follow the step-by-step instructions to fill the
membrane cap correctly.
3.3 Electrical connection: Connect the sensor
as per the electrical connection guidelines provided.
3.4 Installation in the flow-through vessel:
Install the sensor in the designated flow-through vessels as
described in the manual.
3. Measurement / Operation
4.1 Run-in period: Allow the sensor to
stabilize during the initial run-in period as specified.
4.2 Check of the sensor / analysis: Regularly
check the sensor and perform analysis as required.
4.3 Chlorine measurement: Use the FCML 412 for
chlorine measurement following the instructions provided.
4. Maintenance, Cleaning, Storage
5.1 Cleaning the measurement electrode: Follow
the cleaning instructions provided; replace the membrane cap and
electrolyte when necessary.
5.2 Cleaning: Clean the sensor as instructed to
maintain accuracy.
5.3 Storage: Store the sensor properly when not
in use to prevent damage.
5. Technical Data
6.1 Measuring characteristics: Refer to the
technical data section for detailed measuring characteristics.
6.2 Application characteristics: Understand the
application characteristics for optimal sensor performance.
FAQ:
Q: How often should I clean the measurement electrode?
A: It is recommended to clean the measurement electrode and
exchange the membrane cap and electrolyte as needed, typically at
regular intervals based on usage.
OPERATING MANUAL
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® ®
FCML 412 N
FCML 412-M12
FCML 412 N FCML 412 M12
pH-INDEPENDENT SENSOR FOR FREE CHLORINE
FCML 412 N, FCML 412 M12
Copyright © 2025, Xylem Analytics Germany GmbH
Printed in Germany.
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Contents
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Contents
1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1 Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2 Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Safety information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.1 Safety information in the operating manual . . . . . 7 2.1.2 Safety signs on the product . . . . . . . . . . . . . . . . . 7
2.1.3 Further documents providing safety information . 7
2.2 Safe operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.1 2.2.2 2.2.3
Authorized use . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Requirements for safe operation . . . . . . . . . . . . . 8 Unauthorized use . . . . . . . . . . . . . . . . . . . . . . . . . 8
3 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.1 Scope of delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.2 Filling the membrane cap with electrolyte solution . . . . . . 9 3.3 Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.4 Installation in the flow through vessel D-CL . . . . . . . . . . 11 3.5 Installation in the flow through vessel D 19 . . . . . . . . . . 12
4 Measurement / Operation . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1 Run-in period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.2 Check of the sensor / analysis . . . . . . . . . . . . . . . . . . . . 15 4.3 Chlorine measurement with the FCML 412 . . . . . . . . . . 15
5 Maintenance, cleaning, storage . . . . . . . . . . . . . . . . . . . 16
5.1 Cleaning the measurement electrode / exchanging the membrane cap and electrolyte . . . . . . . . . . . . . . . . . . . . 16
5.2 Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 5.3 Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 5.4 Maintenance equipment and replacement parts . . . . . . . 18
6 Technical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
6.1 Measuring characteristics . . . . . . . . . . . . . . . . . . . . . . . . 19 6.2 Application characteristics . . . . . . . . . . . . . . . . . . . . . . . 19 6.3 General data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 6.4 Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
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FCML 412
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Overview
1 Overview
The FCML 412 chlorine sensors are membrane-covered, amperometric sensors for the determination of free chlorine.
1.1 Structure
1
2
3 5
6
4
7
1 Connection FCML 412 N: PG7 gland
FCML 412 M12: Flange plug for adapter ADA CL/IDS
2 Shaft 3 Auxiliary electrode 4 Electrode finger 5 O-ring 14 x 1.8 6 Reference electrode 7 Measuring electrode 8 Valve opening (behind hose ring) 9 Membrane cap 10Membrane holder 11Membrane disk
M48
8 9 10 11
figure 1-1 Structure: Example FCML 412 M12
With its special design (potentiostatic three electrode system), the sensor measures all the free chlorine present (sum of gaseous dissolved chlorine, hypochloric acid and hypochlorite) and the chlorine that is bonded to isocyanuric acid. The sensor has a strongly reduced pH dependence.
The sensor has integrated measuring electronics and delivers a measuring signal that is already temperature compensated. It does not require a zero point adjustment. The routine calibration is carried out through comparison with the photometric DPD method according to DIN 38408.
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Overview
FCML 412 N, FCML 412
1.2 Electrical connection
FCML 412 N FCML 412 M12
The FCML 412 N sensor is connected with the measuring transmitter (e.g. MULTILINE 1000) via a two wire connection.
The wires are used for the power supply of the measuring transmitter and for the transmission of measurement signals (4 – 20 mA current signal).
The FCML 412 M12 sensor has an M12 flange plug for connection to the adapter ADA CL/IDS (see section 5.4 MAINTENANCE EQUIPMENT AND REPLACEMENT PARTS).
The adapter ADA CL/IDS connects the sensor to the MIQ/IDS module of the IQ Sensor Net. Power supply and transmission of the measuring signal are carried out via the adapter ADA CL/IDS.
Except for the different electrical connection, all FCML 412 sensors are identical.
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Safety
2 Safety
2.1 Safety information
2.1.1 Safety information in the operating manual
This operating manual provides important information on the safe operation of the product. Read this operating manual thoroughly and make yourself familiar with the product before putting it into operation or working with it. The operating manual must be kept in the vicinity of the meter so you can always find the information you need.
Important safety instructions are highlighted in this operating manual. They are indicated by the warning symbol (triangle) in the left column. The signal word (e.g. “CAUTION”) indicates the level of danger:
WARNING
indicates a possibly dangerous situation that can lead to serious (irreversible) injury or death if the safety instruction is not followed.
CAUTION
indicates a possibly dangerous situation that can lead to slight (reversible) injury if the safety instruction is not followed.
NOTE indicates a situation where goods might be damaged if the actions mentioned are not taken.
2.1.2 Safety signs on the product
Note all labels, information signs and safety symbols on the product. A warning symbol (triangle) without text refers to safety information in this operating manual.
2.1.3 Further documents providing safety information
The following documents provide additional information, which you should observe for your safety when working with the measuring system: Operating manuals of other components of the FCML 412 N, FCML 412 sys-
tem (power packs, controller, accessories) Safety datasheets of calibration and maintenance equipment (e.g. cleaning
solutions).
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Safety
FCML 412 N, FCML 412
2.2 Safe operation
2.2.1 Authorized use The authorized use of the FCML 412 N, FCML 412 M12 is the stationary measurement of chlorine in drinking water, swimming pool water and process water. Only the operation and running of the product according to the instructions and technical specifications given in this operating manual is authorized (see chapter 6 TECHNICAL DATA). Any other use is considered unauthorized.
2.2.2 Requirements for safe operation Note the following points for safe operation: The product may only be operated according to the authorized use specified
above. The product may only be supplied with power by the energy sources men-
tioned in this operating manual. The product may only be operated under the environmental conditions men-
tioned in this operating manual. The product may not be opened.
2.2.3 Unauthorized use The product must not be put into operation if: it is visibly damaged (e.g. after being transported) it was stored under adverse conditions for a lengthy period of time (storing
conditions, see chapter 6 TECHNICAL DATA).
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Commissioning
3 Commissioning
3.1 Scope of delivery
Sensor FCML 412 with membrane cap M48 Sensor FCML 412 N or Sensor FCML 412 M12
Dropping bottle with 100 ml electrolyte solution ELY-FCML 412 N Polishing strip Operating manual
3.2 Filling the membrane cap with electrolyte solution
NOTE Risk of damage for the sensor in the case of improper handling. Do not touch the electrode finger with your fingers. Do not apply pressure to the membrane disk. Do not unscrew the membrane holder.
When it is delivered, the membrane cap is not filled with electrolyte and is loosely screwed onto the shaft. In order to put the sensor into operation, fill the membrane head as follows:
Filling the membrane cap
1. Unscrew the membrane cap from the electrode shaft. Place the membrane cap on a clean (non-absorbent) surface.
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Commissioning
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2. Cut off the tip of the dropping bottle until the opening in the tip is visible, then fill the membrane cap completely with electrolyte solution making sure it is bubble free.
3. Lift off the hose ring of the membrane cap, which closes the valve opening, from the side so that the valve opening is exposed (see picture below). Hold the sensor shaft in an upright position and place it on the filled membrane cap. Some of the electrolyte solution will leak over the upper edge of the membrane cap while doing this. Then screw the electrode shaft into the membrane cap. For this, first turn the electrode shaft anti-clockwise until the thread catches; then slowly screw in the electrode shaft as far as it will go until no gap can be seen between the sensor shaft and membrane cap.
1 Valve opening
2 Hose ring
1 2
NOTE Overpressure in the membrane cap can destroy the membrane disk. Therefore, make sure the valve opening is not inadvertently closed by your fingers. Excess electrolyte solution must be able to escape freely at any time. Screw slowly so that no back pressure can develop.
4. Using a blunt object, slide the hose ring over the valve opening and insert it evenly in the groove.
5. Rinse off any electrolyte solution adhering on the outside.
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Commissioning
3.3 Electrical connection
How to connect the FCML 412 N sensor to the measuring transmitter or the MIQ/IDS module is described in the operating manual of the measuring transmitter. How to connect the sensor FCML 412 M12 to the MIQ/IDS module is explained in the operating manual of the module MIQ/IDS.
3.4 Installation in the flow through vessel D-CL
The flow-through vessel D-CL is optimized for the FCML 412 N chlorine sensors.
The position in the flow through vessel has a considerable effect on the approach flow and, hence, the measuring function of the sensor. Therefore carefully position the sensor as described below.
Proceed as follows to install the sensor:
1. Slide the black O-ring and then the PVC sliding ring over the sensor. 2. Unscrew the screw connection of the flow-through vessel. 3. Insert the sensor into the flow-through vessel without the cable con-
nected. 4. Slide the screw connection of the flow-through vessel over the sensor. 5. Screw the screw connection of the flow-through vessel onto the flow-
through vessel.
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Commissioning
FCML 412 N, FCML 412
1 3 4
255 mm 94 mm
1 mm 2
50 mm 1 Top edge of the coupling ring 2 Above the middle of the inlet opening 3 Lower edge of the groove 4 Top edge of the sensor
6. Reconnect the sensor connection cable to the sensor.
NOTE When commissioning, always open the feed slowly. A strong shock pressure can destroy the membrane.
3.5 Installation in the flow through vessel D 19
The flow-through vessel D 19 is optimized for the FCML 412 M12 chlorine sensor.
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Commissioning
The FCML 412 M12 has a marking on its shaft for optimum installation in the flow-through vessel D 19.
The position in the flow through vessel has a considerable effect on the approach flow and, hence, the measuring function of the sensor. Therefore carefully position the sensor as described below.
Proceed as follows to install the sensor:
1. Connect the ADA CL/IDS adapter to the M12 flange plug and screw it tight.
2. Push the coupling ring of the flow-through vessel loosely onto the sensor.
3. Insert the sensor with the coupling ring in the flow-through vessel.
1 2
3
4
1 Marking on the FCML 412 M12 2 Top edge of the coupling ring 3 Drain opening 4 Inlet opening
4. Align the marking (1) on the sensor with the top edge (2) of the coupling ring.
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Commissioning
FCML 412 N, FCML 412
5. Tighten the coupling ring by hand.
6. Tighten the coupling ring approx. a quarter turn further with the M32 assembly wrench. Make sure the sensor is firmly attached. Otherwise, it can be pressed out of the flow through vessel by pressure.
NOTE When commissioning, always open the feed slowly. A strong shock pressure can destroy the membrane.
The assembly wrench, size M32, is available as an accessory (see section 5.4 MAINTENANCE EQUIPMENT AND REPLACEMENT PARTS).
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Measurement / Operation
4 Measurement / Operation
4.1 Run-in period
Polarization
Each time the sensor has been refilled it must be polarized. To do this, immerse the connected and voltage-supplied sensor in a well-stirred chlorine solution with at least 5 mg/l chlorine for an hour. Then put the sensor into use (measuring position). The sensor can be calibrated after a stabilizing time of approx. 20 minutes. After approx. one day, a post-calibration should be performed.
The position in the flow through vessel has a considerable effect on the approach flow and, hence, the measuring function of the sensor. Therefore carefully position the sensor as described below.
The sensor filled with electrolyte must not become dry and has to be permanently supplied with electrical voltage. Otherwise the characteristics of the membrane cap, electrode finger and electrolyte will be changed (sometimes irreparably). The sensor may only be stored in an unfilled condition (see also section 5.3 STORAGE).
4.2 Check of the sensor / analysis
Calibration with the DPD-1 method
The chlorine sensor has a linear characteristic curve. Calibration of the chlorine sensor is carried out as a single-point calibration. The calibration value (nominal value) is usually determined photometrically. A common procedure for this is the DPD method for free chlorine. The photometer and test sets for this are described in the WTW catalog or on the Internet.
How to carry out the calibration is described in detail in the operating manual of the measuring transmitter.
4.3 Chlorine measurement with the FCML 412
The FCML 412 chlorine sensor measures inorganic chlorine compounds dissolved in water. The measured values determined with the photometer according to the DPD-1 method (free chlorine) are directly comparable to the values determined by the sensor.
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Maintenance, cleaning, storage
FCML 412 N, FCML 412
5 Maintenance, cleaning, storage
5.1 Cleaning the measurement electrode / exchanging the membrane cap and electrolyte
We recommend to disconnect the sensor from the measuring transmitter before starting any maintenance work. If calibration is not possible due to readings that are too low, the measurement electrode has to be cleaned with the enclosed polishing strip. Proceed as follows:
1. Using a blunt object, lift the hose ring out of the guiding groove and push it to the side so that the valve opening is uncovered. 1 Valve opening 2 Hose ring
1 2
NOTE Negative pressure in the membrane cap can destroy the membrane disk. Therefore, make sure the valve opening is not inadvertently closed by your fingers while unscrewing the membrane cap.
2. Unscrew the membrane cap from the sensor shaft and pour away the electrolyte solution.
3. Rinse the electrode finger and membrane cap with clean water and dab them dry with a clean paper towel.
4. Clean the measurement electrode with the polishing strip. To do so, place the polishing strip on a paper towel and hold it by a corner. Then hold the electrode finger vertically with the tip down and run the tip over the polishing strip two or three times.
NOTE The brown coating on the shell (reference electrode) of the electrode finger must not be polished off. This would destroy the sensor!
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Maintenance, cleaning, storage
5. Fill the membrane cap with fresh electrolyte solution as described in section 3.2, screw it on the sensor shaft and make the sensor ready for measurement.
After exchanging the electrolyte solution and/or membrane cap the sensor has to be repolarized (see section 4.1 RUN-IN PERIOD). If calibration is still not possible after cleaning the measurement electrode, change the membrane cap.
5.2 Cleaning
Removing lime deposits on the membrane cap
Remove lime deposits on the membrane cap as follows:
1. Unscrew the membrane cap from the sensor shaft and pour away the electrolyte solution (see section 5.1).
2. Put the membrane cap into 10 % acetic acid for several hours. 3. Then thoroughly rinse the membrane cap with clean water. 4. Fill the membrane cap with fresh electrolyte solution as described in
section 3.2, screw it on the sensor shaft and make the sensor ready for measurement.
5.3 Storage
NOTE The sensor may only be stored in an unfilled condition.
Proceed as follows to store the sensor:
1. Unscrew the membrane cap from the sensor shaft and pour away the electrolyte solution (see section 5.1).
2. Thoroughly rinse the membrane cap and electrode finger with clean water and dry them dust free.
3. Loosely screw the dry membrane cap on the sensor shaft. The membrane disk must not touch the electrode finger.
Recommissioning For recommissioning, clean the electrode tip with the polishing strip and use a new membrane cap (see section 5.1). The membrane cap can be put into 10 % acetic acid for some hours to remove any lime deposits (see section 5.2).
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Maintenance, cleaning, storage
FCML 412 N, FCML 412
5.4 Maintenance equipment and replacement parts
Description
Accessory kit for chlorine sensor FCML 412, including: 1x membrane cap M48
100 ml electrolyte solution ELY-FCML 412 N
Polishing strip
Model
Order no.
ZBK-FCML 412 N 205246
Adapter for connecting the sensor FCML 412 M12 to an IDS interface
ADA CL/IDS
Flow-through vessel D 19 for chlorine sensor FCML 412 M12
D 19
Flow-through vessel D-CL for chlorine sensor FCML 412 N
D-CL
Accessory for the flow-through vessel D 19 R-SET P 1x assembly wrench M32
108155 401991 201150Y 904030
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Technical data
6 Technical data
6.1 Measuring characteristics
Measuring principle Membrane-covered, amperometric sensor with potentiostatic three-electrode system and integrated measuring electronics
Measuring range
FCML 412 M12-20
FCML 412 M12-2 FCML 412 N
0.01 … 20.00 mg/l Cl2 0.01 … 2.00 mg/l Cl2
Response time
pH dependency
Temperature compensation-
Polarization time
Calibration procedure
t90 (90 % of the final value display after) approx. 120 s Approx. 10 % slope loss per increasing pH unit Automatic, by means of integrated temperature sensor
Approx. 2 hours on commissioning or after exchanging the electrolyte Single-point calibration, e.g. with photometric measurement according to the DPD-1 method as a reference
6.2 Application characteristics
Temperature range
pH application range
Max. admissible overpressure
0 … 45 °C (32 … 113 °F) The measurement medium must be free of ice crystals.
pH 4… 9
D-CL D 19
3·105 Pa (3.0 bar),
3·105 Pa (3.0 bar), Pressureless operation in the flow through vessel is recommended.
Working life of the membrane cap
Approach flow
Typically 1 year (depending on measuring medium) Recommended minimum flow rate in the flow through vessel:
Typical application range
D-CL > 30 l/h D 19 > 15 l/h Drinking water, swimming pool water and mains water in the flow through vessel
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Technical data
6.3 General data
Dimensions FCML 412 N:
FCML 412-M12:
FCML 412 N, FCML 412
200 mm
37 mm 175 mm
25 mm
25 mm
Membrane cap M48 Membrane type Microporous, hydrophilic membrane
Electrolyte ELY-FCML 412 N (from ZBK-FCML 412 N)
Material
Shaft Membrane cap Membrane holder, auxiliary electrode Working electrode Reference electrode Hose ring Cable screw joint
PVC PVC Stainless steel
Gold Ag/AgCl Silicone Polyamide
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Technical data
6.4 Electrical data
FCML 412 N
2-wire connection via permanently mounted cable AK-CL 298 12 … 30 V DC power supply by the measuring transmitter Output signal 4 … 20 mA
FCML 412 M12
5-pin M12 flange connector: for the ADA CL/IDS adapter by means of screw/plug connection
Power supply: +/- 5 … 15 V DC through the MIQ/IDS module
Nominal slope: -1000 mV/ppm
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Disposal
FCML 412 N, FCML 412
7 Disposal
Handle and dispose of all waste in compliance with local laws and regulations.
EU only: Correct disposal of this product — WEEE Directive on waste electrical and electronic equipment This marking on the product, accessories or literature indicates that the product should not be disposed of with other waste at the end of its working life. To prevent possible harm to the environment or human health from uncontrolled waste disposal, please separate these items from other types of waste and recycle them responsibly to promote the sustainable reuse of material resources. Waste from electrical and electronic equipment can be returned to the producer or distributor.
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Xylem |zlm|
1) The tissue in plants that brings water upward from the roots; 2) a leading global water technology company. We’re a global team unified in a common purpose: creating advanced technology solutions to the world’s water challenges. Developing new technologies that will improve the way water is used, conserved, and reused in the future is central to our work. Our products and services move, treat, analyze, monitor and return water to the environment, in public utility, industrial, residential and commercial building services settings. Xylem also provides a leading portfolio of smart metering, network technologies and advanced analytics solutions for water, electric and gas utilities. In more than 150 countries, we have strong, long-standing relationships with customers who know us for our powerful combination of leading product brands and applications expertise with a strong focus on developing comprehensive, sustainable solutions. For more information on how Xylem can help you, go to www.xylem.com.
®
Service and Returns: Xylem Analytics Germany Sales GmbH & Co. KG WTW Am Achalaich 11 82362 Weilheim Germany
Tel.: +49 881 183-325 Fax: +49 881 183-414 E-Mail wtw.rma@xylem.com Internet: www.xylemanalytics.com
Xylem Analytics Germany GmbH Am Achalaich 11 82362 Weilheim Germany
Documents / Resources
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Xylem FCML 412 Analog Chlorine Sensors [pdf] Instruction Manual FCML 412 N, FCML 412 M12, FCML 412 Analog Chlorine Sensors, FCML 412, Analog Chlorine Sensors, Chlorine Sensors, Sensors |