Hot work permit without a gas test!

For more information about Gas Monitors, please download the Gas Monitors Training Course

Recently the US Chemical Safety Board released a video animation of the sequence of events at a DuPont facility near Buffalo,NY that had an accident due to hot work being carried out on a storage tank that still had explosive vapors. Surprisingly the workers who carried out the hot work were issued a mandatory "hot work" permit WITHOUT carrying out any gas test ! (A gas test is a test that is carried out to ascertain the presence of an explosive gas before allowing hot work such as welding or cutting inside a plant).This negligence unfortunately caused the accident. It could have been easily prevented had a Gas Monitor been used.

The CSB has posted an animated video that details the incident. watch it below.

Interesting video on Gas Detector training

For more information about Gas Monitors, please download the Gas Monitors Training Course here

Types of toxic gas monitors and gas detectors

For more information about Gas Monitors, please download the Gas Monitors Training Course


There are various technologies that are used to make toxic gas detectors. Also these instruments are available in various forms, like fixed, portable or pocket types. There are different sensors used to detect different types of toxic gases. Some types of sensors can detect a variety of different gases, others can detect only one type of gas.

Fixed toxic gas detectors

These are very commonly found in large manufacturing plants and similar facilities. Each fixed gas detector is mounted at a place where it is very likely to sense the toxic gas, in case of a leak. The detector may or may not have a local display that shows the concentration of the gas. Each detector is connected via cables to a central system, that is monitored by plant personnel. In case of a leak this panel will generate alarms to warn the operators about the dangers and may also carry out any interlock actions (like triggering closure of valves or initiating a shutdown).

Portable toxic gas detectors

Portable gas monitors are used by workers to sweep a work area, to know if there is any toxic gas lurking around the area. These detectors are also called as handheld gas detectors. These detectors are normally battery powered and have a display with a buzzer and lights, to warn the operator, in case a dangerous level of toxic gas is detected. They may have their own inbuilt sampling pumps, to draw air into the sensor. Some variants also store data, to calculate time weighted average values, peak values and other important data for regulatory compliance.

Pocket toxic gas detectors

A typical personal toxic gas monitor is shown in the picture above. These are similar to the portable types, except that they are very small and meant to be carried by individual workers, by use of a belt clip, or inside a pocket. These instruments are normally throw away types and have a lifetime of about two years (lesser if they are constantly exposed to the toxic gas being detected). They also have a display, buzzer and light, but due to the small size there are no sampling pumps or data logging chips inside.

Typically, a worker carries it with him, when he enters an area that could contain such a gas (for example, he will carry a pocket H2S detector when he enters a process vessel for cleaning, if it had processed H2S previously). The vessel might still have some amount of Hydrogen Sulfide inside (or the gas may enter later through some piping that still remains connected). The worker's pocket gas detector now acts like his guardian angel, or personal bodyguard and warns him immediately, should the gas be detected. This allows him to escape or be rescued by his co-workers.

Where to get more information?

You can download a very useful e-learning course on toxic gas detectors here. This training course on gas monitors covers all types of gas detectors and gas monitors, including toxic gas monitors. It will take about three to four hours to complete and if you take an online test (optional, free of cost), you can also get a certificate of achievement, that would be a useful testimonial.

Importance of proper Gas Monitors proved in Bayer Cropscience incident

For more information about Gas Monitors, please download the Gas Monitors Training Course

By now, all of those of you in industry must have heard about the Bayer Cropscience incident that took place in August 2008 in Institute, W. Va. There was an explosion in the Methomyl unit and two workers were killed. Several lapses were pointed out by the US Chemical Safety Board that led to the unfortunate incident. One issue however that was not highlighted by the board but emphasized by local investigative reporters, was the non working of several toxic gas detectors in the facility. The management claimed that the detectors were disconnected from the monitoring system due to maintenance, but this itself seems wrong. Generally only one detector is removed at a time for maintenance or calibration. The next one should be removed only when the first is in place.
Secondly there were no such toxic gas detectors placed along the western side of the plant. The wind direction unfortunately on that day was from the plant's western side to its neighbors (communities staying near the plant).
The explosion that took place was very close to a tank containing the extremely toxic chemical Methyl Isocyante (MIC), the same that caused the now infamous Bhopal disaster.
All in all it just shows how seriously companies should take the selection, installation and proper operation and maintenance of gas detectors and gas monitors in their plants. If not then disasters may be looming!

Four gas monitor or PID meter? Which one do you use?

For more information about Gas Monitors, please download the Gas Monitors Training Course

Many people in the process industry used to use a standard "four gas" monitor for years, until the advent of PID type gas monitors. So this is just an open ended question to you all... what's your favorite meter? To the newbies, a four gas monitor is basically what it says, a portable gas monitor that can measure upto four different types of gases. These can be any mix of four sensors, or a mix of one LEL sensor (for explosive gases and vapors), an Oxygen sensor (for confined space entry) and two toxic gas sensors (say H2S and Chlorine for example). These type of four gas monitors have been used for several years and are workhorses of the plant operations and maintenance teams. However the advent of PID type meters has meant a threat to the domination of the four gas monitor. Essentially a PID meter stands for a gas monitor that uses a PID (Photoionization detector) to measure a wide range of gases. These cover most compounds found in industry such as most volatile organics and toxic gases like H2S. Many PID meters also come with a built in software and systems to automatically do datalogging and calculations of parameters like TWA, etc for regulatory compliance. Calibration is easier too, with just one gas IsoButylene being used.
So tell us what's your favorite meter- PID or four-gas?

Toxic gas monitors should be installed in all public closed spaces-not just in industrial plants!

For more information about Gas Monitors, please download the Gas Monitors Training Course

One imagines that toxic gas monitors are necessary to be installed only in industrial plants, not in churches. Right? Well, you’re dead wrong!
AP reports that firemen and other authorities in Madison, Wisconsin said that six people — including a toddler — got sick from carbon monoxide poisoning during a Sunday church service in Madison. Paramedics were called to attend to a 2-year-old child who was reported to be groggy . The parents of the child decided to transport the child to the hospital on their own.
Fortunately, by the time a second distress call was reported to the local Fire Department, Engine Company 4 responded, bringing along monitors to check air quality at the church. The portable Carbon Monoxide toxic gas monitors showed a CO level of 3000 ppm- more than 100 times the safe limit!
The incident shows the importance of having portable toxic gas monitors handy in all places and not just industrial plants.

How do pocket H2S monitors work?

For more information about Gas Monitors, please download the Gas Monitors Training Course

This post will give you a brief idea about how a pocket h2s monitor works. A pocket h2s monitor is a small instrument that is meant to be used by a worker who is working in an area that may get poisoned with Hydrogen Sulfide gas (referred to as h2s). The H2S monitor is a small portable toxic gas monitor that has a clamp at the back, so that it can be easily clamped to the worker's belt or clothes. Alternatively it can be carried in a pocket. Intrinsically Safe versions are also available which means that they can be use din hazardous areas.

The pocket h2s monitor consists of a sensor (mostly electrochemical), associated electronics (including an LCD display, buzzer, light/LED) and a housing with the clamp. It has to be calibrated with a known concentration of h2s gas in air using a standard calibration gas bottle. Every time a worker enters a confined space area that may later on allow some traces of h2s inside, the worker has to carry this monitor, so that whenever h2s ingress happens, the h2s monitor will go off, sounding a loud buzzer and flashing a red LED as a warning to escape at the earliest.
Some versions can even transmit this alarm wirelessly to a remote control room or to a host unit that may be mounted in the area. This enables the workman's colleagues to rescue him, should he be unable to escape on his own.
A typical unit looks like this (shown above).