Best Ethylene Oxide (ETO) Gas Detector (Expert Pick)

Ethylene Oxide Detector, Ethylene Oxide Meter, ETO Detector, ETO Meter -

Best Ethylene Oxide (ETO) Gas Detector (Expert Pick)

An ethylene oxide gas detector, also known as an ETO gas detector, senses the concentration of ethylene oxide (C2H4O) in the air. These devices are used for personal protection in hazardous gas environments. In hospitals, ETO detectors are used to protect health care workers when sterilizing medical instruments. 



  • Small and low cost ETO gas detectors helps with worker safety.
  • ETO gas detectors are available for less than $399.
  • Wall-mounted ETO systems are also used to prevent catastrophic ETO gas leakages.
  • Bump testing and calibration can be forgotten by users.
  • Sensors typically last from 24 to 36 months.
  • Health care workers are exposed to ethylene oxide in hospitals.

What Is an Ethylene Oxide Gas Detector?

An ethylene oxide (ETO) gas detector is an instrument used to detect the concentration of ethylene oxide in the air. These devices (specifically the Forensics Detectors FD-90-ETO) have a long-life battery, large screen that displays the ETO concentration, and a belt clip to connect to clothing. In order to protect users, these gas detectors also have LED, vibration, and buzzer alarms.

Ethylene oxide gas detectors are also known as ETO monitors, ethylene oxide sniffers, ethylene oxide analyzers, and ethylene oxide gas testers. These names all refer to the same device, an ethylene oxide gas detector.

What Does an Ethylene Oxide Meter Detect?

A ethylene oxide detector senses ethylene oxide (ETO) gas and displays the levels in parts per million (ppm).

What Is Ethylene Oxide Gas?

Ethylene oxide has the chemical symbol C2H4O. It is a very useful yet dangerous gas, hence the need to monitor and check air concentrations.

Is Ethylene Oxide Toxic?

Yes it is.

When exposed to ETO, you may experience respiratory irritation, lung injury, nausea, vomiting, and headaches. Symptoms from hospital workers are presented here.

Long term and chronic exposure studies have shown possible neurotoxicity. This is a problem for hospital workers that sterilize instruments with ETO.

    Can I Smell Ethylene Oxide Gas?

    Yes, humans can smell ethylene oxide gas.

    It has been described as a sweet smell. Others have described it as "pleasantly to sickeningly sweet, fruity, alcoholic, or acetone- or ether like."

    The ethylene oxide odor threshold is between 260 ppm and 700 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 ETO. Over time, the nose becomes desensitized to the odor - this phenomena is called olfactory fatigue.

    What Are the Different Types of Ethylene Oxide Gas Detectors?



    Ethylene Oxide Gas Leak Detector 


    These are handheld combustible gas leak detectors used to check for ethylene oxide leaks in sterilizers. ETO is a combustible and can be monitored using a combustible gas leak detector. These units are excellent for spot and point checking.
    ethylene oxide gas leak detector


    Ethylene Oxide Detector for Personal Protection

    The majority of ethylene oxide gas detectors are portable. These are small, battery-powered units with an ethylene oxide sensor that can be clipped onto your clothes for personal protection. 

    ammonia gas meter
    Ethylene Oxide Gas Monitor for Stationary Fixed Wall 

    Wall-mounted units provide continuous protection and warning of ethylene oxide gas leaks. These devices are perfect for indoor uses, such as a hospital room used to sterilize instruments with ETO. 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 an Ethylene Oxide Gas Sensor Work?

    An ethylene oxide gas detector is composed of electronics and an ETO sensor. The gas 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 ETO concentration reading. If the measurement exceeds the pre-set ETO alarm value, the alarms are triggered.


    Sensor Technology



    Ethylene Oxide (ETO)

    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

    What Are Safe Ethylene Oxide 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):

    0.1 ppm, 10-hour TWA

    5 ppm, 10-minute ceiling

    Occupational Safety and Health (OSHA)

    1 ppm average over 8 hours

    5 ppm average over 15 minutes (Permissible Exposure Limit)

    American Conference of Governmental Industrial Hygienists (ACGIH)

    1 ppm average over 8 hours

    What Is an Ethylene Oxide Gas Detector Used For?

    Ethylene oxide gas is used in a variety of manufacturing and industrial processes, as listed below. It is primarily used in hospitals to sterilize medical instruments. Because ETO is toxic, it is important to monitor for employee safety.

    • ETO for medical sterilization (hospitals): Ethylene oxide is used to chemically sterilize heat-sensitive materials in hospital settings. Health care workers can be exposed to high levels of ETO when sterilizing, leading to toxic gas exposure. One study showed ethylene oxide breathing zone levels of up to 250 ppm.
    • ETO for fumigation agriculture:  ETO is used to fumigate grain bins and wheat sacks. Others agricultural items include food, commodities such as tobacco, and grains.
    • ETO for industrial uses: Ethylene oxide is heavily used in industry to make polyester and other products such as ethylene glycol (antifreeze).

    ethylene oxide sterlization

        What Is the Best Ethylene Oxide Gas Detector?

        There are many ethylene oxide gas detectors on the market. The reputable brands include the following:

        How Do I Select an Ethylene Oxide Detector?

        To select the best ethylene oxide gas detector, follow this simple guide:

          • What do I need it for?
            • Personal Protection?
            • Gas Leak Detection?
            • Continuous Room Monitoring?
          • What is my budget and operating cost budget?
          • Do I need advanced functions such as data-logging or Bluetooth?
          • Do I need specific accreditations with the monitor such as ATEX or a NIST traceability calibration certificate?
          • Do I require a belt clip for attaching the device to my clothes?
          • Do I need after-sales support, USA headquarters, or fast calibration services?

        How Long Does an Ethylene Oxide Sensor Last For?

          Ethylene oxide detectors incorporate small electrochemical sensors that usually last between 24 and 36 months. 

          Gas leak detectors using semiconducting metal oxide sensors last over 5 years. These are used in ETO gas leak detectors.

          How Do I Test My Ethylene Oxide Detector?

          The best way to test your ethylene oxide gas detector is to expose it to a known gas source. Generally referred to as bump testing, this is a good practice to perform daily. Frequent testing is especially important in personal protection applications where safety is paramount - more about bump testing in the next section.

          What Is an Ethylene Oxide Detector Bump Test?

          • Bump testing is a procedure where the user exposes the detector to a small amount of “blast” target gas to ensure the detector operates and alarms as programmed.
          • The function of this test is to verify proper operation and build user confidence, particularly in hazardous applications.
          • It is recommended to bump test when first purchased, with subsequent testing every week. If using in LIFE-THREATENING and / or DANGEROUS applications, bump test daily. 
          • Ethylene oxide bump test gas can be found here.

          What Is Ethylene Oxide Detector Gas Calibration?

          Ethylene oxide gas detector calibration is the technical task of adjusting the detector to a more accurate gas reading. Over time, the sensors on the device will degrade or produce drifting readings. We suggest calibrating your ETO detector every 6 to 12 months, the typical time period for gas detectors. 

          Gas calibration is a technical task that requires certain key pieces of equipment. These include a calibration gas bottle, gas regulator, tubing, and calibration cap fitting. You need to communicate with the manufacturer to determine the recommended calibration gas concentrations and mixtures. For the Forensics Detectors ETO gas monitors, we recommend the calibration gas here.

          Be attentive and calibrate daily if:

          • The user employs the device as an analytical tool where accuracy is paramount.
          • The device is used in an extreme environment (temp and humidity extremes create sensor drift).
          • The user is performing an imminently dangerous application.
          • Bump testing fails. In this case, you must calibrate to make sure the sensors and monitor operate properly.
          • The ETO gas detector alarms in the fresh air. This could mean that the sensor has drifted past an alarm set-point.

          Calibration and bump testing are mandatory because injury or death can occur if the device fails. Take it very seriously. 

          Also, it is prudent to have a calibration schedule that the owner or employees strictly follow. See gas calibration here.

          How Do I Take Care of My Ethylene Oxide Gas Sensor?

          • Store your ETO gas detector at a normal room temperature.
          • Store it away from electromagnetic or magnetic sources, such as phones.
          • Store it in a clean environment with no dust or particles.
          • Store away from any exhaust gas, concentrated vapors, and harsh chemicals.
          • Clean the casing of your detector with a damp cloth.
          • Store it in a stable place where there are no vibrations or continuous shaking.

          How Do I Properly Use an ETO Gas Detector?

          When operating an ETO gas detector, there are some important tips to consider. After reading your product manual, be sure to keep these tips in mind:

          • Turn ON the ETO gas monitor in the fresh air. 
          • Ensure the ETO gas monitor is within its calibration period.
          • Ensure the monitor has been bump tested and validated as operational. 
          • Check the alarm set-points. Set your alarms as desired (some units may not have adjustable alarms).
          • If performing analytical measurements, keep the unit stationary. Ensure humidity and temperature are also tracked and are as constant as possible.

          Is Ethylene Oxide Gas Explosive?

          Yes it is.

          Ethylene oxide is flammable at concentrations above 2.7% in air.

          Therefore, ETO gas has a lower explosive limit (LEL) of 2.7% - this means it is too lean to burn.

          The upper explosive limit (UEL) of ETO is 100%.

          Final Words

          • Ethylene oxide is important in our modern day life. It is extremely important for sterilization in hospital operations.
          • ETO gas detectors can be used for personal protection in hazardous gas environments when sterilizing.
          • ETO gas leak detectors are useful to determine any ETO gas leaks from sterilizers.
          • ETO gas detectors are affordable, costing less than $400 per unit. 

          About The Author

          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 having a cold beer. 

          Read more about Forensics Detectors here.

          Phone: +1 424-341-3886



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