ISE Sensor for Ammonium

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ISE Sensor for Ammonium

The TT-GP-NH4-6013 is the ONLY Ammonium (NH4+) ion selective sensor that can be:

  • Used in heavy industrial process and wastewater treatment system
  • Provides measurements up to saturated ammonium levels
  • Operate continuously at temperatures up to 50 degrees Celsius
  • Fully submersible without the use of any standpipe or immersion tubes
  • RADEL with Double O-Ring Front End — ¾” MNPT Back End
  • Hot-tap insertion valve retractable assembly (up to 10 psi); or
  • Sanitary assembly and tri clover fitting (up to 10 psi)
  • Acid/Fluoride Resistant
  • Sulphide Resistant
  • Slurry Resistant (High Abrasion)
  • High Capacity KYNAR Reference (HDPE for ultralow option)
  • Proprietary toughened glass
  • Sensor holder and valve retractable assembly sold separately
  • Digital smart sensor technology (optional)
    • No hard wiring – plug-n-play connectivity
    • Sensor stores calibration data, analyser configuration and sensor history
    • Hot-swap for quick sensor change-out
    • No interaction with analyser – sensor data auto uploads
  • Description
  • Downloads
  • Application & Use
  • Case Studies

TT-GP-NH4-6013 ISE Sensor for Ammonium

The Turtle Tough Ammonium ion selective electrode is designed for valve retractable and sanitary use with double o-ring seals and 3/4" MNPT back end thread.  It is the ONLY Ammonium (NH4+) ion selective sensor that can be used in heavy industrial process and wastewater treatment systems, providing measurements up to saturated levels and can operateammonium-ise continuously at temperatures up to 50°C.

Turtle Tough provide an unrivalled and proven solution for Ammonium measurement. The ISE sensor is capable of measuring from 0.090 to 18,000 ppm (5X10-6 to 1.0 Molar) and its lowest limit of detection is 0.004 ppm (5X10-7 Molar).  It will operate over a broad pH range from 2.5 to 11.

For applications where the pH is above 8.0, a pH sensor is added to the analyser to provide compensation of both pH and temperature. The sum of the measured unbound ammonium ions and dissolved ammonia gas formed must be computed as a function of both real-time continuous pH & temperature parameters.

Our valve retractable sensor is uniquely designed to interface with both our hot-tap insertion valve retractable assembly or our  sanitary fitting.

Osubmersible_ammonium_ion_selective_sensorur hot-tap assemblies are a common feature in industries where direct access to the process is required inline or in-tank without interruption to service.

Shown LEFT in full submersible configuration.

Before proceeding further, it is recommended that a review of the following technical documents that describes the general provisions for online ion selective measurements:

Digital Smart Sensor Technology (DSS)

This sensor is available with our digital smart sensor technology. This plug and play sensor has a quick connect fitting, eliminating the need for hard wiring to the analyser. On-board sensor memory allows the storage of calibration data, analyser configurations and sensor service history. This allows the sensor to be conveniently maintained and calibrated off-site or in the laboratory and pre-programmed with calibration data and analyser configurations.  This stored information automatically uploads to the analyser upon connection and eliminates the need for any interaction with the analyser, greatly simplifying the change-out of sensors. A service log stored on the sensors is ideal for maintenance and quality assurance records.

TTMA-multichannel-analyser-3 270x334Analyser

The TT-GP-NH4-6013 interfaces with the TT-MA or TT-MAD ISE Modular Analysers. The unique modular design enables you to create a fully functional, multi-parameter analyser with any combination of different TT-MA analytical modules.

The TT-MA and MAD Analyser modules have the following features:

  • Scale 4-20mA analogue output is standard for all measurement modules. Active 4-20mA can support remote external displays to allow for viewing measured values in control panels, secondary field locations, or instrumentation shops.
  • Modbus digital output optional.
  • Precise factory-calibrated linear analogue output allows excellent use in control applications. All analogue outputs have built-in trim calibration support, including both offset and span adjustments.
  • Calibration of temperature compensation element is available for all measurement modules.
  • Economical Custom Configurations offer the freedom to pay only for the specific modules you need; pH, ORP, Dissolved Oxygen, Ion Selective (ISE) and temperature.
  • Easy to use simple and intuitive three-button operation with no complex codes to memorize for most day-to-day tasks.
  • Easy to read displays with bright three-digit LED displays are visible even in bright sunlight and do not suffer from the common problems associated with LCD displays, such as environmental fatigue and wear.
  • Weatherproof NEMA 4X CSA/UL rated & IP65 enclosures include high quality sealing cable glands that are ideal for weatherproof sealing on sensor, power, and output cables.
  • Power supply is CSA/UL/CE approved universal 100 to 240 VAC 50/60 Hz power supply module for line powered operation, or 3-wire 24VDC powered operation.


Municipal potable water and water treatment facilities for chloramination monitoring.  Municipal wastewater treatment for aeration basin monitoring & control of nitrification and denitrification process (usually in conjunction with dissolved oxygen measurement).  Industrial facilities required to monitor and/or treat the ammonia prior to discharge for compliance and other environmental remediation.  Environmental monitoring in rivers, lakes and ponds for public health and safety.  Any free or total ammonia measurement that needs to operate with minimal cleaning & recalibration frequency (i.e. remote sites).

Application Difficulty Index:6/10

This sensor is design for difficult applications with a difficulty index up to 6/10

Maintenance FREE

Turtle Tough pH and ORP sensors are a completely sealed assembly and are sealed for life.  This provides extreme process resistance as well as a totally maintenance free sensor which greatly increases sensor life and reduces labour costs.  A Turtle Tough sensor does not contain any O-rings, washers, gaskets, or serviceable components/assemblies. It does not require refreshing or refilling of electrolyte. The only requirement is regular cleaning in accordance with our recommended cleaning schedule for your application. Regular cleaning will prolong the life of your sensor and ensure hassle free operation.

Recommended Cleaning Schedule

The recommended cleaning interval is based upon the difficulty index for your application.

Recommended Cleaning Schedule

Application Difficulty Rating

Cleaning Schedule








Twice (2x) per week



If a Turtle Tough pH/ORP sensor response slows down, it is most likely the result of a fouled  reference or dirty coated glass.  Cleaning should be performed as required and will vary across  applications.  See cleaning instructions.


The standard shelf life for all Turtle Tough pH and ORP sensors is one year from the date of shipment. Sensors stored longer than this period may still be functional but are no longer under warranty. Sensors should be stored in a cool, dry location with the sensor tip (sensing element) oriented toward the ground.  All sensors come standard with a conditioning solution in the cap. This conditioning solution is 50% pH 4 buffer and 50% saturated potassium chloride (mixed by volume). The sensor cap should be kept tightly affixed to the sensor body and sealed with common PVC tape when the sensor is not in use. Sensors that are to be returned for shelf life warranty claim must have the original sensor cap and conditioning solution intact to be eligible for warranty replacement.

Avoiding Thermal Shock

For high temperature applications where process liquid exceeds 70°C you will prolong the life of the sensor by avoiding thermal shock. Thermal shock occurs when you rapidly change the temperature of the sensor from hot to cold or vice versa. This rapid expansion/contraction of sensor components can damage internal elements and cause micro-cracking that will accelerate the rate of deterioration. In extreme cases it will crack the sensing element causing a total failure.  To avoid this sensor should be heated or cooled slowly during removal/insertion and cleaning and calibration processes. Consult your Turtle Tough representative for techniques to avoid thermal shock.

Conditioning After Calibration

After the sensor has been cleaned, it must be thoroughly rinsed with deionised water to remove any residual cleaning reagents. The sensor can then be soaked in pH 4 buffer to recondition the pH and reference elements. Some sensors will also require conditioning in saturated potassium chloride if the reference junction has been depleted of the ions in the solid state conductive polymer (typical for clean water applications). Condition the sensor in saturated potassium chloride and/or pH 4 buffer for whatever period of time is required to achieve optimal calibration results.

Please refer to your sensor manual for correct installation, maintenance and use.

Measurement of Ammonia in Municipal Drinking Water for sterilization with Monochloramines

Real-time continuous online measurement system for ammonia

  •       Low Initial Procurement Cost compared to competing technologies and offerings
  •       No need for chemical feed and rebuilding of sensors
  •       Lower Cost of Ownership due to very long sensor lifetime, low maintenance & cleaning requirements for inline, immersion & submersion ion selective sensors
  •       Intuitive and easy to use TT-MA analyser programmed and configured for ammonia and nitrate ion selective analysis
  •       All new systems come preconfigured, precalibrated and fully qualified to install, plug-in and immediately place into service especially for  compliance purposes
  •       Only periodic 1-point grab sample offsetting is required – this “Standardize” calibration can be performed WITHOUT removing sensor from service!

The Problem

A number of municipal drinking water plants wish to carefully control their level of free ammonia (often also described as total nitrogen of NH3-N) and chloramine (also called monochloramine or MCL) used to ensure that the water remains suitable for human consumption.  Until now, the technologies to measure the two species of interest for this application (free ammonia and chloramine) have been only possible with expensive sampling analysers that required reagents, and significant operator involvement to ensure nominal operation.  The result has been the operator and time intensive method of periodic grab sampling to ensure the sterilization system is working within the appropriate limits (typically 0.1 to 0.6 ppm for free ammonia for example) continues to be used at most facilities.  The high cost of such sampling analysers and the process of grab sampling can often mean that not as much information about the process is available as would be desired for control and monitoring purposes.  The labour demands of grab sampling can be particularly problematic with smaller and remote facilities that have less frequent operator presence due to personnel limitations.  In some conditions, the pH and temperature can fluctuate throughout the year, meaning that the percent of ammonia (NH3-N) that will be in the measurable ionized ammonium form can vary.

The Solution

In cases where monochloramine and pH are already measured, a single or dual channel ammonium analyser is employed to monitor the free (residual) ammonia levels.  In cases where no monochloramine  measurement is performed, the monochloramine and free ammonia measurement can be combined into one dual channel analyser to perform both measurements.  For some installations a triple channel configuration of ammonia, ammonia and pH is the most cost effective option although other combinations are possible as well.  The ability to measure in particular ammonia online in real time with minimal calibration and cleaning requirements makes it possible to record and control the process between grab samples, while the low up-front commissioning costs and low residual cost of ownership in terms of sensors and maintenance makes it possible to measure at more points of interest without exceeding budgetary restrictions.  Since the conversion of dissolved ammonia gas to the ammonium ionized form in solution is a pH and temperature dependent process, Turtle Tough offers the ability for this pH and temperature compensation to be performed in real-time as well to yield information about the total amount of free ammonia that is present (see graph below for details about this phenomenon).  The graph shows that ammonium is the dominant form of free ammonia under most pH and temperature conditions common for municipal drink water facilities.

The online ammonium ion selective measurement system can be calibrated for 1-point offset without removing it from service, making it ideal for low maintenance continuous use.  The online ion selective measurement systems for ammonia can readily be referenced to most any grab sampling laboratory or portable method (including the popular colorimetric kits and existing sampling analyzers).  Two-point calibrations need only be performed for new sensors in most cases once again minimizing the service needs.  These online ISE systems are available for a wide variety of installation styles and can be integrated into any modern PLC and DCS systems.

Sensors are available in a wide variety of options including preamplifiers to support long cable lengths up to 90 metres and fully submersible assemblies to interface with any existing process connections and configurations.  In addition, popular twist lock quick disconnect inline styles are also supported for easy of removal for periodic cleaning should it be required as are “plumb-and-play” low-flow panel that minimize installation time and labor.