Chlorination of potable water, waste-water effluent and cooling water is widely used throughout the world to control biological activity in the water. Disinfection of potable water with chlorine ensures that tap water is safe to drink once it has passed through the distribution system.

Wastewater disinfection helps to ensure that receiving streams are safe for recreational use and cooling water chlorination reduces biofouling that can degrade heat transfer efficiency. In addition to these common uses, there are many other applications where chlorine addition helps to reduce biological contamination. Since the Q45H/79 is capable of measuring down to 0.001 ppm, it is also ideal for use in dechlorinaiton applications where chlorine discharge limits are often extremely low.

Residual chlorine is found in many chemical forms in water systems. Residuals in clean water are often predominantly free chlorine while wastewater, cooling water and chloraminated water can contain mixtures of free chlorine, combined chlorine and organochlorine species. Measurement of residual chlorine can be relatively difficult where a variety of chlorine forms exist and a measurement of "Total Residual Chlorine" is often required in these applications. This total chlorine measurement is normally done by reacting the chlorine in a water sample, buffered to pH 4, with potassium iodide. All of the various chlorine compounds react with the iodide to release an equivalent amount of iodine and the released iodine is measured using various methods.

Many on-line monitors for total residual chlorine use the iodomeric method for measurement, often measuring the current between two platinum electrodes to determine the iodine concentration. ATI's Model Q45H/79 Total Residual Chlorine Monitor uses this same standard iodometric measurement technique, but with a membraned sensor for measuring the iodine in solution. The system takes the reacted sample containing iodine and uses a membraned amperometric sensor rather than exposed electrodes. The gas permeable membrane allows only iodine to react with the sensor. Sample contaminants are reduced from coming in contact with a 40-60 micron filter located in the inlet flow block.

The Q45H/79 monitor is an on-line automated chemistry system that provides the components necessary to perform total residual chlorine measurement. In operation, a small amount of sample is pumped into the system and mixed with pH 4 buffer and then with potassium iodide. At pH 4, chlorine compounds in solution react as follows (equation shown for one chlorine compound only):

The sample to be measured is pumped to the inlet flow block located in the side of the chemistry module, from which a small filtered sample is then taken and mixed with pH 4 buffer and potassium iodide. The reacted sample now moves to a special flowcell assembly where the iodine is measured with a membraned amperometric sensor. The signal from the sensor with temperature are then processed by the monitor and displayed on the monitor in parts per million total residual chlorine. The Q45H/79 is available either with the monitor mounted on the chemistry module or the monitor can be separated up to 100 feet (25' standard) from the chemistry unit if required.

Sample tubing is connected to the inlet overflow assembly using 1/4" ID flexible tubing. Recommended sample flow rate is 3-15 gallons per hour (.2-1 LPM). While the chemistry unit uses only a small fraction of this sample, higher flow keeps sample delivery times to a minimum. Excess sample simply overflows into a drain chamber. A 1/2" id hose barb is provided for connection of drain tubing.

Features

• Sensing: Measurement is made with a direct reading membraned amperometric iodine sensor.
• Standard Method: Total chlorine is measured using EPA recommended method of reaction of sample with buffer and potassium iodide and measurement of iodine released in the reaction.
• High Accuracy, High Sensitivity: Measures from 0.001 ppm to 20.00 ppm
• Large Alphanumeric LCD Display: Provides total residual chlorine display, alarm status indication and all configuration information.
• Control Relays: Two 6 amp relays programmable for control or alarm function.
• Isolated Output: Two assignable 4-20 mA outputs configured to track residual chlorine, temperature or assigned to PID control.
• Selectable PID Controller: PID includes manual operation feature and diagnostic feature for relay notification of control problems.

Specifications - Electronic Monitor

Range	0-200 ppb, or 0-2.000, 0-20.000 ppm
Accuracy	±0.01 ppm or 0.5% of FS
Repeatability	±0.01 ppm or 0.5% of FS
Linearity	0.1% of FS
Zero Drift	< 0.01 ppm per month
Display	Large 4 digit LCD main display, 0.75" characters, 12 digit alpha-numeric second line display
Control Relays	Two SPDT relays, 6A @ 250 VAC 5A @ 24 VDC, resistive
Relay Mode	Programmable for control or alarm function
Analog Output	Two solated 4-20 mA, 550 Ohms max load, assignable
Temperature	-20-60°C
Humidity	0-95% RH, non-condensing
Power	115/230 VAC, 50/60 Hz
Enclosure	NEMA 4X (IP-66) wall mount optional

Specifications - Chemistry Module

Sensor	Membraned I2 gas sensor
Sensor Cable	25' standard, 100' maximum
Response Time	99% in 1 minute
Sample Pump	Internal tubing pump, 15 cc/min
Buffer/KI Pump	Internal tubing pump, 0.06 cc/min
Sample Flow Block	PVC with internal 40-60 micron sample filter
Temperature Limits	0-50°C
Sample Flow Rate	3-15 GPH (.2-1 LPM) at sample flow block
Sample Inlet	¼" ID hose barb
Sample Drain	¼" ID hose barb

Ordering Information

For pricing please call AFC International at 800-952-3293, 219-987-6825 or fax 219-987-6826 or email sales@afcintl.com.

Description	Catalog No.
Series Q45H/79 Residual Chlorine Monitor, Integrated Single Enclosure System, 120 VAC	Q45H/79-1-1
Series Q45H/79 Residual Chlorine Monitor, Separate Monitor and Chemistry Module, 120 VAC	Q45H/79-2-1

Downloads

Series Q45H/79 Total Residual Chlorine Monitor datasheet