Best Chlorine Gas Detector (2024 update)

Chlorine Detector, Chlorine Meter, Cl2 Detector, Cl2 Meter -

Best Chlorine Gas Detector (2024 update)

A chlorine gas detector, or Cl2 gas meter, is a critical safety device that detects and monitors the concentration of chlorine gas in the air. These gas detection instruments are designed to alert personnel of dangerous chlorine gas exposure levels. Chlorine gas is widely used as a disinfectant in households, swimming pools, and industrial settings, as well as an oxidizing agent in water treatment facilities, bleaching processes, and chemical workflows. By continuously monitoring the air for the presence of chlorine gas and providing real-time measurements of its concentration, chlorine gas detectors play a vital role in protecting individuals from the harmful effects of this toxic gas.



  • A Small and low cost Chlorine gas detector can help to alarm when a dangerous toxic situation occurs.
  • Chlorine can off-gas when in water, so gas detectors are required.
  • Chlorine gas detectors are available for less than $349.
  • Used in water, treat, industry, waste, and many other industries.
  • Bump testing and calibration can be missed by users.
  • Chlorine sensor elements typically last from 24 to 36 months.
  • Along with high toxicity, chlorine can form explosive compounds.

Best Chlorine Gas Detector?

There are many chlorine gas detectors on the market. The top reputable brands include the following:

What Is a Chlorine Gas Detector?

A chlorine (Cl2) gas detector is an instrument used to detect the concentration of Cl2 in the air or in a toxic environment. These devices (specifically the Forensics Detectors FD-90A-Cl2) have a long-life battery lasting over 24 hours on one charge, large screen that displays the chlorine gas concentration in ppm, and a belt clip to connect to clothing or a bag. In order to protect users, these gas detectors also have LED, vibration, and buzzer alarms to warn in dangerous situations.

Chlorine gas detectors are also known as Cl2 monitors, chlorine meters, chlorine analyzers, and Cl2 gas detectors. These names all refer to the same device, a Chlorine gas meter.

What Does a Chlorine Meter Detect?

A chlorine detector senses chlorine (Cl2) gas and displays the levels in parts per million (ppm). The harmful effects of Cl2 on human health and the environment warrant the use of chlorine detectors to prevent high levels of exposure.

What Is Chlorine Gas?

Chlorine has the chemical symbol Cl2.

This gas is slightly yellow or green with an irritating smell. Cl2 is a very useful but dangerous gas. Due to is many positive uses in various industries, it requires monitoring to protect humans from inhalation.

Is Chlorine Gas Toxic?

Yes it is.

When exposed to chlorine gas, you may experience coughing, blisters on the skin, burning in the throat and eyes, difficulty breathing, nausea, and fluid in the lungs. Avoiding chlorine exposure is essential to avoid occupational hazards.

Older individuals and those who smoke may have more severe reactions to chlorine gas exposure. In this case, inhaling Cl2 may lead to acute lung injury or respiratory distress. Up to 1% of people exposed to chlorine gas die.

Is Chlorine in Swimming Pools Safe?

For the most part, chlorine in swimming pools is safe.

Chlorine is a necessary addition to prevent potentially dangerous microbes from infecting swimmers. The chemical can cause skin and hair to dry out but is not nearly as dangerous as its gaseous form.

The bigger concern is how chlorine in a pool can react with other chemicals. Swimmers can introduce urine, shampoo, lotion, or conditioner to the pool which can form unhealthy compounds. These irritants can bother the eyes and throat but can be removed with wind or good ventilation. In general, the benefits from chlorine disinfection greatly outweigh any potential exposure risks.

Even with no additional reaction, chlorine can off-gas from chlorine dissolved in water. Without enough ventilation, accumulation of chlorine gas can create a toxic and dangerous environment. This is a problem for heated indoor pool situations where off-gasing is higher and due to limited ventilation, chlorine accumulation can be a problem.

chlorine gas meter

Can Bleach Release Chlorine Gas?

Yes it can.

Household chlorine bleach can release Cl2 when mixed with other cleaning agents. Carefully read the product labels of household cleaners and avoid mixing bleach and acids. Acids can be found in drain cleaners, glass cleaners, and some dishwasher detergents.

In addition to acids, mixing bleach with ammonia will produce chloramine gas, a modified form of chlorine gas. Exposure to chloramine gas results in coughing, shortness of breath, chest pain, and irritation to the mucous membranes.

Unfortunately, mixing chlorine bleach and household cleaners is a common mistake. There are more than 2,000 incidents per year in the US. In 2019, a Buffalo Wild Wings employee accidentally spilled a household cleaner on the floor. Another worker cleaned the floor with a different cleaner, creating a toxic mixture of bleach and acid that released Cl2 and resulted in the death of the store's manager.

chlorine bleach gas detector

Does Chlorine out-gas and off-gas?

Yes it does.

Chlorine evaporates from the water, which is called out-gassing or off-gassing. Chlorine is a gas but can be placed in water as a "volatile solute" meaning the molecules can diffuse in the water. They will escape into the atmosphere over time, outgassing or off-gassing.

The rate of outgassing depends on variables such as temperature, water agitation and atmospheric humidity. Increasing temperature and agitation increases outgassing.

Another factor is surface area. The more surface area to the atmosphere (i.e. shallow water) the faster the outgassing.

What Should I Do If I've Been Exposed to Chlorine Gas?

If you suspect that you have been exposed to chlorine gas, it is important to evacuate to an outdoor environment with no traces of Cl2 exposure. Wash the affected areas to stop eyes and skin from burning. Medical professionals can help manage symptoms such as wheezing.

Preventing exposure is important for safety and can be achieved with an Cl2 gas detector.

    Is Chlorine (Cl2) and Chlorine Dioxide (ClO2) the Same?

    No, chlorine gas and chlorine dioxide gas are not the same. While they are both forms of chlorine, they have different chemical properties and uses.

    Chlorine gas (Cl2) is a yellow-green gas that is highly reactive and can be toxic if inhaled. It is commonly used as a disinfectant and bleaching agent in water treatment, swimming pools, and industrial processes.

    Chlorine dioxide gas (ClO2) is a yellow-green gas that is less reactive and less toxic than chlorine gas. It is also used as a disinfectant in water treatment and industrial processes, but it is often preferred over chlorine gas because it is more effective against certain types of bacteria and viruses, and it does not produce harmful byproducts like chloramines.

    Overall, while both chlorine gas and chlorine dioxide gas have some similar uses, they are different chemicals with different properties and should be handled and used according to their specific characteristics.

    Can I Smell Chlorine Gas?

    Yes, humans can smell chlorine gas. It is described to have a pungent and irritating odor similar to bleach.

    The chlorine odor threshold is estimated to be 0.3 ppm. See here.

    However, it is a bad idea to rely on your sense of smell to determine the "concentration" of an aromatic gas like Cl2. Over time, the nose becomes desensitized to the odor - this phenomena is called olfactory fatigue.

    What Are the Different Types of Chlorine Gas Detectors?

    Chlorine Detector for Personal Protection

    The majority of chlorine gas detectors are portable. These are small, battery-powered units with a chlorine sensor that can be clipped onto your clothes for personal protection. They typically come in two versions. The diffusive type allows the Cl2 gas molecules to naturally diffuse to the sensor head. On the other hand, pump-driven detectors include an internal or external micro-pump that moves air over the sensor head. These devices sometimes incorporate probes for point sampling uses.

    phosphine gas detector

    Chlorine Gas Monitor for Stationary Fixed Walls

    Wall-mounted units provide continuous protection and warning of chlorine gas leaks. These devices are perfect for indoor uses. If the levels pass the preset threshold (i.e., 1 ppm OSHA TWA), the unit will provide an LED and buzzer warning.

    fixed wall mount H2S monitor

    How Does a Chlorine Gas Sensor Work?

    A chlorine gas detector is composed of electronics and a Cl2 sensor. The sensor converts the detected gas concentration to an electronic signal for analysis by the onboard microprocessor. After receiving the electrical signal, the processor displays the Cl2 concentration reading. If the measurement exceeds the pre-set alarm value, the alarms are triggered.


    Sensor Technology



    Chlorine (Cl2)

    Electrochemical Sensors

    The gas reacts with a working electrode, triggering an electrochemical redox reaction. The generated current is proportional to the detected gas level.

    • Small, fast response, & cheap
    • Easy to integrate with electronics
    • Immediate ON
    • Limited life from 24 to 36 months
    • Influenced by temperature and humidity

    chlorine sensor

    What Are Safe Chlorine Gas Levels?

    Various government agencies have recommended gas exposure limits, examples can be seen below:


    Recommendation / Requirement

    National Institute for Occupational Safety and Health (NIOSH)

    NIOSH Recommended Exposure Limit (REL):

    0.5 ppm, 10-hour TWA

    0.5 ppm, 15-minute ceiling

    Occupational Safety and Health (OSHA)

    1 ppm average over 8 hours

    1 ppm average over 15 minutes (Permissible Exposure Limit)

    American Conference of Governmental Industrial Hygienists (ACGIH)

    0.5 ppm average over 8 hours

    What Is a Chlorine Gas Detector Used For?

    Chlorine gas is used in a variety of household and industrial processes, as listed below. Because Cl2 is toxic, it is important to monitor for employee and homeowner safety.

    • Chlorine for manufacturing of paper and cloth: 

      Chlorine is one of the most commonly produced chemicals and is used as a bleaching agent. Cl2 is necessary in the creation of white, dirt-free paper and cloth. In addition, a bleached surface is necessary for dyeing. Chlorine gas detectors are necessary in manufacturing facilities to monitor any accidental releases.

    • Chlorine as a household disinfectant:

      Chlorine is found in many household cleaners, such as bleach. This affordable disinfectant can be used to clean kitchens, bathrooms, and any other areas to prevent the spread of germs. Be sure to never mix chlorine bleach with acids or ammonia.

    • Chlorine for water treatment: 

      Chlorine is used to kill dangerous bacteria in swimming pools, drinking water, and sewage. This additive breaks chemical bonds in cells to render them inert. Stopping water-based diseases makes recreational and drinking water safe for everyone.

      How Long Does a Chlorine Sensor Last For?

        Chlorine detectors incorporate electrochemical sensors that last between 24 and 36 months. 

        How Do I Test My Chlorine Detector?

        The best way to test your chlorine gas detector is to expose it to a known Cl2 gas source. This gas is available in a gas cylinder.

        Cl2 bump testing is a good practice to perform daily. Frequent testing is especially important in personal protection chlorine gas applications where safety is paramount.

        What Is Chlorine Detector Gas Calibration?

        Chlorine gas detector calibration is the task of tweaking the calibration curve to increase accuracy. Calibration is needed for every gas detector. Over time, the Cl2 electrochemical sensor on the device will degrade or produce drifting readings. We suggest calibrating your Cl2 detector every 6 to 12 months, the typical time period for gas detectors. See gas calibration here.

          Is Chlorine Gas Explosive?

          No it is not.

          Chlorine gas itself is not explosive, but it can be a hazardous and reactive material if handled improperly. Chlorine gas can react with other chemicals, particularly in the presence of heat or light, to produce explosive compounds. For example, if chlorine gas comes into contact with organic materials, such as fuels or oils, it can react to form explosive compounds.

          Has Chlorine Gas been used for Chemical Warfare?

          Yes it has. Chlorine gas has been used as a weapon many times for warfare purposes.

          • Chlorine bombs in Iraq by ISIS. Used together with conventional explosive devices to attack road side trucks, suicide bombers and a truck filled with chlorine was detonated.
          • Chlorine was used as a poison Gas in WW1 by the Germans. The gas was used with artillery shells. One hundred and firfty tons of chlorine gas was used against two French divisions at Ypres, Belgium. 
          • Chlorine gas was used by the Syrian President Bashar Assad's regime.
          chlorine gas detector

          Fatal Injuries involving Chlorine Gas Exposure

          There have been several notable incidents involving chlorine gas that resulted in fatalities and injuries:

          1. Missouri, 2002: A flex hose ruptured during the unloading of a train car at a chemical plant, releasing approximately 16,900 pounds of chlorine gas. This incident injured 67 persons​.

          2. Macdona, Texas, 2004: A freight train accident released 9,400 US gallons of chlorine gas and other toxic chemicals. The accident caused injuries to at least 40 people and resulted in three fatalities, including two residents and the train conductor​.

          3. South Carolina, 2005: A freight train derailed, releasing an estimated 11,500 US gallons of chlorine. This incident resulted in nine deaths and at least 529 persons seeking medical care​.

          4. Jos, Nigeria, 2015: An explosion of a chlorine gas storage tank at a water treatment plant killed eight people.

          5. Aqaba, Jordan, 2022: A tank holding chlorine gas fell and ruptured, leading to 14 deaths and over 260 injuries​.

          Final Words

          • Chlorine plays a crucial role in various industries, including paper and cloth manufacturing, water treatment, and disinfection. However, its widespread use also necessitates the implementation of robust safety measures. Chlorine gas detectors are essential for personal protection in hazardous Cl2 gas environments, and are commonly sold to pool customers, industries utilizing chlorine for disinfection, and water treatment facilities. These gas detection devices continuously monitor the air for the presence of chlorine gas, providing real-time measurements and alerts when concentrations exceed safe levels. In addition to personal protection, Cl2 gas leak detectors are invaluable tools for identifying and addressing chlorine gas leaks in chemical plants and water treatment facilities, helping to prevent potential health risks and environmental hazards. With Cl2 gas detectors being affordable, costing less than $399 per unit, there is no reason for industries dealing with chlorine not to prioritize the safety of their workers and the surrounding community by deploying these life-saving devices.

          About The Author

          Dr. Kos Galatsis ("Dr.Koz") is the President of FORENSICS DETECTORS, where the company operates from the scenic Palos Verdes Peninsula in Los Angeles, California. He is a subject matter expert on gas sensor technology, gas detectors, gas meters, and gas analyzers. He has been designing, building, manufacturing, and testing toxic gas detection systems for over 20 years.

          gas detector expert

          Every day is a blessing for Dr. Koz. He loves to help customers solve their unique problems. Dr. Koz also loves spending time with his wife and his three children going to the beach, grilling burgers, and enjoying the outdoors.

          Read more about Forensics Detectors here.

          Phone: +1 424-341-3886