Hydrogen Cyanide (HCN) Gas Detector (Expert Analysis)
A hydrogen cyanide detector, also known as an HCN gas detector, senses the concentration of HCN in the air. These devices are used for personal protection in hazardous gas environments. Hydrogen cyanide is used for chemical processes, fumigation, mining, electroplating, and the production of synthetic plastics. In addition, HCN is emitted during reactions between cyanide and acid or combustion.
What Is a Hydrogen Cyanide Gas Detector?
A hydrogen cyanide (HCN) gas detector is an instrument used to detect the concentration of hydrogen cyanide in the air. These devices (specifically the Forensics Detectors FD-90A-HCN) have a long-life battery, large screen that displays the HCN concentration, and a belt clip to connect to clothing. In order to protect users, these gas detectors also have LED, vibration, and buzzer alarms.
Hydrogen cyanide gas detectors are also known as HCN monitors, hydrogen cyanide sniffers, hydrogen cyanide analyzers, and HCN gas testers. These names all refer to the same device, an HCN gas detector.
What Does a Hydrogen Cyanide Meter Detect?
A hydrogen cyanide detector senses HCN gas and displays the levels in parts per million (ppm).
The growth of hydrogen cyanide detectors has increased due to its use as a fumigant in response to the need to replace methyl bromide. Hydrogen cyanide is used against scale insects on citrus trees and other pests on greenhouse plants.
What Is Hydrogen Cyanide Gas?
Hydrogen cyanide has the chemical symbol HCN. It is a very useful yet dangerous gas, hence the need to monitor and check air concentrations.
Is Hydrogen Cyanide Toxic?
Yes it is.
Hydrogen cyanide is a systemic chemical asphyxiant, interfering with oxygen usage in the body. When exposed to hydrogen cyanide gas, the brain, heart, and lungs will be affected and can become rapidly fatal. Avoiding hydrogen cyanide gas exposure is essential to protect your family and coworkers.
HCN fumes are also dangerous to animals. Levels of hydrogen cyanide as low as 0.2 ppm were found to be toxic to fish.
In 2017, an electrical fire filled up a three-story house with toxic smoke. In just ten minutes, a pair of cats died from hydrogen cyanide poisoning. Luckily, a couple of other cats and the other occupants made it out unscathed.
What Should I Do If I've Been Exposed Hydrogen Cyanide Gas?
If you suspect that you have been exposed to hydrogen cyanide, it is important to evacuate to an outdoor environment with no traces of HCN exposure. Seek medical attention immediately. Medical professionals can help manage symptoms such as reduced respiratory or heart function.
Preventing exposure is important for safety and can be achieved with an HCN gas detector.
Can I Smell Hydrogen Cyanide Gas?
Yes, most humans can smell hydrogen cyanide gas. It is described to have a bitter almond smell. The gas doesn't always give off an odor and even when it does, it cannot be detected by everyone.
The hydrogen cyanide odor threshold is around 0.6 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 HCN. Over time, the nose becomes desensitized to the odor - this phenomena is called olfactory fatigue.
What Are the Different Types of Hydrogen Cyanide Gas Detectors?
Hydrogen Cyanide Detector for Personal Protection
The majority of hydrogen cyanide gas detectors are portable. These are small, battery-powered units with an HCN sensor that can be clipped onto your clothes for personal protection.
|Hydrogen Cyanide Gas Monitor for Stationary Fixed Wall||
Wall-mounted units provide continuous protection and warning of hydrogen cyanide gas leaks. These devices are perfect for indoor uses. If the levels pass the preset threshold (i.e., 10 ppm OSHA TWA), the unit will provide an LED and buzzer warning.
How Does a Hydrogen Cyanide Gas Sensor Work?
An hydrogen cyanide gas detector is composed of electronics and an HCN 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 HCN concentration reading. If the measurement exceeds the pre-set alarm value, the alarms are triggered.
Hydrogen Cyanide (HCN)
The gas reacts with a working electrode, triggering an electrochemical redox reaction. The generated current is proportional to the detected gas level.
What Are Safe Hydrogen Cyanide 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):
4.7 ppm, 10-hour TWA
4.7 ppm, 10-minute ceiling
Occupational Safety and Health (OSHA)
4.7 ppm average over 8 hours
4.7 ppm average over 15 minutes (Permissible Exposure Limit)
American Conference of Governmental Industrial Hygienists (ACGIH)
4.7 ppm average over 8 hours
What Is a Hydrogen Cyanide Gas Detector Used For?
Hydrogen cyanide gas is used in a variety of manufacturing and industrial processes, as listed below. Because HCN is toxic, it is important to monitor for employee and homeowner safety.
- HCN for fumigation: Hydrogen cyanide is used as an insecticide and fungicide. Stored grains facilities, ships, and other buildings can be fumigated with hydrogen cyanide gas to protect from pests. It is effective against a wide range of pests and has been used as a fumigant for over a century. Proper equipment and employee training is essential to protect human health.
- HCN for electroplating: Manufacturing activities such as electroplating, metal mining, metallurgy, and metal cleaning can be achieved with hydrogen cyanide.
- HCN for manufacturing: Hydrogen cyanide is used widely in the production of synthetic fabrics, plastics, paper, and dyes.
Can Hydrogen Cyanide Gas Contaminate Food or Water?Yes, hydrogen cyanide can contaminate water and food through factory emissions. The EPA and other agencies have thresholds put into place to protect the public from HCN toxicity. This is why it is so important that facilities monitor their HCN output using a hydrogen cyanide detectors.
What Is the Best Hydrogen Cyanide Gas Detector?
There are many hydrogen cyanide gas detectors on the market. The reputable brands include the following:
- Forensics Detectors Hydrogen Cyanide Detector
- RC Systems Hydrogen Cyanide Detector
- Draeger HCN Detector
- Honeywell HCN Gas Detector
How Do I Select a Hydrogen Cyanide Detector?
To select the best hydrogen cyanide gas detector, follow this simple guide:
- What do I need it for?
- Personal protection?
- Measuring HCN levels in silos?
- Continuous room monitoring?
- 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 any features such as a belt clip?
- Do I value USA support or fast calibration services?
How Long Does a Hydrogen Cyanide Sensor Last For?
Hydrogen cyanide detectors incorporate electrochemical sensors that last between 24 and 36 months.
How Do I Test My Hydrogen Cyanide Detector?
The best way to test your hydrogen cyanide gas detector is to expose it to a known gas source. Bump testing is a good practice to perform daily. Frequent testing is especially important in personal protection applications where safety is paramount.
What Is a Hydrogen Cyanide Detector Bump Test?
- Bump testing is a procedure where the user exposes the HCN detector to a “blast” gas. The gas triggers a bump to the detector 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.
- Hydrogen cyanide bump test gas can be found here.
What Is Hydrogen Cyanide Detector Gas Calibration?
Hydrogen cyanide 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 HCN 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 HCN 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 HCN 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 Hydrogen Cyanide Gas Sensor?
- Store your HCN gas detector at a normal room temperature.
- Store it away from electromagnetic interference sources such as phones.
- Store it in a clean environment.
- Store away from any exhaust gas, concentrated vapors, and harsh chemicals.
- Clean the detector with a damp cloth.
- Store it in a stable place where there are no vibrations occur.
How Do I Properly Use an HCN Gas Detector?
When operating a HCN gas detector, there are some important tips to consider.
- Read your product manual, or watch any support videos.
- Turn ON the HCN gas monitor in the fresh air.
- Ensure the HCN 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 Hydrogen Cyanide Gas Explosive?
Yes it is.
Hydrogen cyanide is flammable at concentrations above 5.6% in air.
Therefore, HCN gas has a lower explosive limit (LEL) of 5.6% - this means it is too lean to burn.
The upper explosive limit (UEL) of HCN is 40% - this means it is too rich to burn.
- Hydrogen cyanide is important in our modern day life. It is extremely important for fumigation, electroplating, and plastic manufacturing.
- HCN gas detectors can be used for personal protection in hazardous gas environments.
- HCN gas leak detectors are useful to determine any gas leaks occur in fumigated areas and manufacturing facilities
- HCN gas detectors are affordable, costing less than $399 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.
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.