When we say that we repair and calibrate monitors and can get the work done fast, we mean it!
We here at National Safety, Inc. have known Bob Henderson for a very, very long time. He is one of the countries top experts on Gas detection in the world. If you deal with gas detection or confined space issues, this webinar is going to be of immense value to you.
Yesterday, I gave you a link to download a new white paper by ISC on “Why Bump Testing Saves Lives”. Today I wanted to let you know about all the other great articles relating to gas detection available on the ISC website. Below is a complete list of all the articles available. It will probably require you to submit some basic contact information but ISC is a reputable company that you can trust not to sell your information and, for the amount of help that they provide in exchange, it is definitely submission that I suggest you make. ISC is one of the world leaders in gas instrumentation and can provide you with a lot of information and help, even besides these links. If you can’t find the answer in one of these articles you can contact Dave Wagner directly here. You now have access to one of the top leaders in the industry; he’s just a mouse click away!
Today’s post is an article by Donald P. Galman. Thank you Donald, for giving me permission to use it (See the bottom of the article for more information about Donald Galman as well as how to contact him)
Special Challenges with Gas Detection
By Donald P. Galman
What Mark Twain wrote about words can apply to a gas monitoring system. ‘The difference between what’s right and what’s almost right is like the difference between lightning and a lightning bug.’
In other words, when it comes to protecting your facility from hazardous gases, it pays to know the difference between gas monitoring strictly for compliance and gas monitoring for true life safety as well as operational efficiency.
Industrial processes increasingly involve the use or manufacture of highly dangerous substances, particularly toxic and combustible gases. Inevitably, occasional escapes of gas occur, which create a potential hazard to the industrial plant, its employees and people living nearby. Worldwide incidents involving asphyxiation, explosions and loss of life are a constant reminder of this problem.
While life safety is a major benefit of gas detection, don’t forget that gas monitors also contribute to worker health, property protection and operational productivity, all of which impact the bottom line.
The industrial hygienist, as a proactive safety leader of the workplace, needs timely, accurate warnings of a gas leak so that building occupants can be evacuated in time, if necessary, to a safe place, and so that gas leaks can be mitigated quickly to prevent the overtaking or destruction of property.
Choosing the right sensing technology, the right gas instrumentation installation scheme and the right mix of fixed and portable monitors will do the job.
“How many detectors do I need?” and “Where should I locate them?” are two of the most common questions about installing gas detectors, and probably two of the most difficult to answer. Unlike other types of safety-related detectors, such as smoke detectors, the location and quantity of detectors required in different applications is not clearly defined.
The placement of detectors should be determined through collaboration. This meeting of the minds includes the advice of experts with specialized knowledge of gas dispersion; experts with knowledge of the process plant system and equipment involved; and safety and engineering personnel. The agreement reached on the location of detectors also should be recorded.
Detectors should be mounted where the gas is most likely to be present. Locations requiring the most protection in an industrial plant or commercial building would be around gas boilers, compressors, pressurized storage tanks, cylinders or pipelines. Areas where leaks are most likely to occur include valves, gauges, flanges, T-joints and filling or draining connections.
THE DANGER OF GOING IT ALONE
It is all too easy to make mistakes when the industrial hygienist chooses to configure a gas monitoring system alone, says Troy Baker, a gas monitoring consultant with Honeywell Analytics. “Too many don’t pay attention to rooms adjacent to the room which is being monitored. One should have an idea of what industrial processes are performed or what equipment is used in these adjacent areas: arc welding? Propane-driven forklifts? The gases generated here can drift into adjacent areas, causing a toxic-combustible cocktail.”
In his 23 years of experience installing gas monitors, Baker has seen his share of mistakes with gas monitoring installations, such as not calibrating or commissioning instruments properly, improperly positioning the equipment, underestimating the amount of sensors needed, using the wrong sensor or not fully understanding a sensor’s limits.
“I have observed that some otherwise very knowledgeable fire marshals, for example, mistakenly believe that the LEL sensor on their portable gas detector can apply to all flammable gases, including ammonia. In fact, the chemical composition of different hydrocarbons can vary tremendously. The explosive threshold between methane, or natural gas, and jet fuel, for example, can differ by 300 percent,” says Baker.
BEWARE THE GAS COCKTAIL
“Under-monitoring is a frequent mistake,” Baker continues. “An insidious problem to deal with is the dangerous blending of toxic and combustible gases.” Ammonia leaks, for example, are seldom purely ammonia; often, they are mixed with other liquids such as those from lubricants to cleaning solvents. These substances effectively can change the lower explosive threshold from, say, 40,000 parts per million to 37,000 parts, he says. These toxic and combustible threats are common at wastewater plants, chemical plants, rubber and other specialty manufacturing facilities.
Baker cites many other examples: A mechanical room that uses flammable gases may give off carbon monoxide; a battery room that uses forklifts may give off carbon monoxide that potentially can mix with off-gassing elements from hydrogen charging stations; propellants used in heating elements; and more.
GUIDANCE FOR GAS MONITORING
Considerable guidance is available from standards such as EN50073, a guide for selection, installation, use and maintenance of apparatus for the detection and measurement of combustible gases or oxygen. Similar international codes of practice, e.g. National Electrical Code (NEC) or Canadian Electrical Code (CEC), may be used where applicable. In addition, certain regulatory bodies publish specifications giving minimum gas detection requirements for specific applications. These references are useful, but tend to be either very generic and therefore too general, or application-specific and therefore irrelevant in most applications.
There are, however, a number of simple considerations to keep in mind when designing a gas monitoring system:
- To detect gases that are lighter than air (e.g., methane and ammonia), detectors should be mounted at a high level and preferably use a collecting cone.
- To detect heavier-than-air gases (e.g., butane and sulfur dioxide), detectors should be mounted at a low level.
- Consider how escaping gas may behave due to natural or forced air currents; mount in ventilation ducts if appropriate.
- When locating detectors, consider the possible damage caused by natural events, such as rain or flooding. For detectors mounted outdoors, use the weather protection assembly.
- Use a detector sunshade if locating a detector in a hot climate and in direct sun.
- Consider the process conditions. Butane and ammonia, for instance, normally are heavier than air, but if released from a process line that is at an elevated temperature and/or under pressure, the gas may rise rather than fall.
- Detectors should be positioned a little way back from high pressure parts to allow gas clouds to form. Otherwise, any leak of gas is likely to pass by in a high speed jet and not be detected.
- Consider ease of access for functional testing and servicing.
- Detectors should be installed at the designated location with the detector pointing downwards to ensure that dust or water will not collect on the front of the sensor.
- When siting open path infrared devices, ensure that there is no permanent obscuration or blocking of the IR beam. Some types of short-term blockage may be accommodated.
- Ensure the open path devices are mounted to sturdy structures that are not susceptible to vibration.
SERVICING A GAS MONITORING SYSTEM
A vital part of ensuring that fixed and portable gas detection equipment correctly operates is periodic servicing, maintenance and calibration. Gas detection applications vary widely, and so do the factors that affect the frequency of servicing required for proper operation. A suitable service period that takes account of each application’s unique set of factors must be established.
Traditionally, gas detection users had their own in-house service departments that were responsible for servicing, maintaining and calibrating their gas detection equipment and other safety-related equipment. Increasingly, many users now choose to outsource part or all of this function in order to reduce fixed costs and at the same time ensure that people with specialist knowledge of the equipment are responsible for it. It also is becoming more common for leading gas detection companies to also offer service of third party gas detection equipment as well as their own. As users continue to demand better efficiencies from outsourced suppliers, the trend in the future likely is to require gas detection companies to offer a “one-stop shop” for the service and maintenance of complete safety systems.
Gas detection company service departments also offer site surveys, installation, commissioning and training. Advice from experts in gas detection helps ensure the selection of the most suitable detection technologies and most appropriate detector locations.
Properly commissioning a system ensures that it fully is functioning as designed and accurately detecting gas hazards. Many companies require that employees who use personal gas detection equipment, or work in areas that have fixed systems installed, are formally trained on the use and routine maintenance of the equipment. Service training departments may offer certified training courses designed to suit all levels of ability from basic gas detection principles through to advanced, custom-designed technical courses.
Some gas detectors now offer ‘smart’ sensors that are pre-calibrated and can be fitted and used without the need for additional calibration and setup in the field. The additional use of intrinsically safe design also can allow the “hot swap” of these sensors without the need for removing power from the detector. Other recent innovations include the use of “auto-cal” routines where the user is taken through a sequence of on-screen calibration steps to ensure correct set up. These innovations help keep service times to a minimum while ensuring accurate calibration.
The modular design of modern gas detectors enables more efficient servicing. The replacement of modules rather than component level service/repair greatly reduces turnaround time and therefore system down time.
APPLIED KNOWLEDGE IS POWER
Choosing the right instrumentation, installation scheme and service plan for monitoring hazardous toxic or flammable gases can go a long way to avert threats to people, property and your company’s bottom line.
The industrial hygienist who is proactive about gas monitoring, works with management to anticipate problems and takes action to prevent problems before they happen contributes to increased productivity, reduced insurance and medical costs, reduced operating costs and safe, healthy workers.
Donald Galman is an editor and writer for Honeywell Analytics, Honeywell’s gas monitoring instrumentation business. Contact him at 847-955-8389 or email@example.com. Visit Honeywell Analytics online at www.honeywellanalytics.com.
Some examples of various types of gas monitors
Providing protection from up to five potential atmospheric hazards including oxygen, combustible and toxic gases, GasAlertMicro 5 is unparalleled in its versatility, capability and overall value. BW’s newest addition to its water-resistant line of portable gas detectors has transformed the market with its matchless array of features.
Continuously monitoring and displaying concentrations of up to five gases, the compact and lightweight GasAlertMicro 5 was designed and engineered with an extensive host of applications in mind.
- Integral concussion-proof boot
- Optional integral motorized pump option for remote sampling
- Powered by three AA alkaline batteries or a hot-swappable rechargeable battery pack
- Triple alarms (audible, visual and vibrating)
- Multi-language support in English, French, German, Spanish and Portuguese
- Large, user selectable backlit LCD
- Four alarm levels: Low, High, TWA and STEL
- Compatible with MicroDock II Automatic Test and Calibration Station
- Datalogging models store and recall event information
- Wide range of user selectable field options including password protection, safe and stealth modes.
- Full function self-test confirms sensor, battery and circuitry integrity and audible/visual alarms on activation
BW Technologies has raised the bar for maintenance-free detection with the new GasAlertClip Extreme. Providing two years of protection from H2S, SO2, CO or O2, the water-resistant GasAlertClip Extreme has a built-in concussion-proof boot and is ideal for amphibious operations and high-moisture environments.
Equipped with two alarm levels and an internal vibrator, the GasAlertClip Extreme now features four visual LEDs, and a high-output audible alarm.. The large, alphanumeric display provides instant notification of gas alarms, test status, life remaining (months then days then hours) and peak (maximum) exposures encountered.
The GasAlertClip Extreme`s advanced microprocessor performs a full function self-test automatically on startup and on demand to verify sensor, circuit and battery integrity, as well as audible/visual alarm operation.
Generating a permanent record of gas alarm events has never been easier. The GasAlertClip Extreme allows for effortless transmission of stored event data to a cordless printer or a PC for review and analysis.
Despite being loaded with features, the GasAlertClip Extreme is compact and light, which makes it comfortable to wear. Clip it to your lapel, pocket, belt or hardhat for unequalled protection.
Available as a 3-year monitor for CO or a 2-year monitor for H2S, CO SO2 or O2
Rig Rat III wireless, multi-point detection system
The Rig Rat III wireless multi-point system continuously monitors for toxic gases, combustibles and oxygen hazards. The self-contained, intrinsically safe site controller is equipped with built-in alarms for instant notification. Independent power, wireless digital signal transmission and plug-in options provide total flexibility. Engineered for maximum cost-effectiveness, the Rig Rat III transmits real-time digital data as far as 1.8 miles (3 km). Installation costs are reduced by up to 75% through eliminating the need for cabling, wiring, conduit and trenching.
The solar-capable Rig Rat III is completely modular in design, with plug-in ports for all field interfaces, including remote sensors, remote alarms and relays. Add, change or reconfigure system components as your requirements evolve.
The Rig Rat III’s microprocessor-based operation and forefront sensor technology assures peerless reliability and performance. The Rig Rat III is the ultimate in stand-alone detection.
Field Tough: Rig Rat III provides unwavering performance in extreme conditions, from deserts to the Arctic.
Easy Installation: Equipped with a rugged weatherproof stainless steel enclosure and built-in mounting flanges, simply mount the detector to the wall and supply power.
Facility Monitoring: Multi-point systems can be expanded to 100 or more individual monitoring points, with each detector coded to a separate channel.
Perimeter Monitoring: The most cost-effective solution to perimeter monitoring.
Portable Monitoring: The only portable, multi-point monitoring system in the world–field-proven on mobile work sites, such as drilling/service rigs, HAZMAT and disaster response teams.
Detector Sub-Site Controller: The detector can activate remote relays and a solenoid driver to control emergency shutdown devices (ESD), building ventilation systems and other field interfaces.
- Independent power and radio signal transmission
- Microprocessor operation ensures performance and reliability
- Flexible power choices–battery, solar, 110/230 VAC
- Encoded digital signal transmission up to 1.8 miles (3 km)
- Real-time LCD readouts for all detectors and sensors
- Simple, straightforward, user-friendly operation
- Modular engineered design
- Status panel advises all features and functions
- Plug-in ports for remote sensors and options
- Dual alarm levels for each sensor (adjustable)
NOTE: Listed below are all the parts and pieces of the Rig Rat III. This is primarily designed for users who already have a unit in service and are looking for replacement parts or looking to expand their already existing system. Because there are so many different options and features, we highly recommend that a facility that is looking at installing a new system from scratch call our instrumentation specialist at 1-800-213-7092 so that we can assist you.
Additional links to:
Tomorrow we will have a special guest from Honeywell Analytics who will be speaking about “Special Challenges with Gas Detection”
Other pertinent information regarding gas monitors
- Be aware that certain compounds can “poison” sensors and cause them to read inaccurately or alarm when they shouldn’t. Silicone or silicone based products are one of the main culprits in this regard. We have had many instances where companies have complained that the sensors were failing only to find out that the instruments had been cleaned with silicone based cleaners or had been exposed to silicone in some other manner. Other “poisons” include Hydrogen Sulfide, Phosphates and Lead. Additionally Freon, trichloroethylene and methylene chloride can cause the sensors to fail.
- Be aware also that the nature of the work being done can often change the nature of the atmosphere. Compressors, welding, etc… can produce fumes and vapors that can rapidly render the air hazardous. Continued monitoring is essential.
- It is important to understanding the nature of the potential hazards and to adequately prepare for them. This means setting alarm setpoints low enough to allow workers to get themselves out of danger before the atmosphere become hazardous. It also means planning escapes to allow plenty of time.
It is beyond the scope of this document to go into the various types of gases, vapors and other hazards. Anyone who is going to be using a gas monitor should be properly trained in the nature of the hazards that they might be encountering as well as in the use of the gas monitor in order to insure that they are safe at all times.
This document is only a “basics of…” and there is much, much more that goes into fully understanding and using gas monitors and dealing with atmospheric hazards.
Additional training classes and continued education is highly recommended.
When should I be using a gas monitor?
A gas monitor should be used in any situation where there might be an impure atmosphere. Confined spaces, where gases may accumulate are an obvious example of such a situation (See “The Basics of Confined Space” for further information).
It is important to make sure that the instrument you are going to be using has been calibrated and is functioning properly. Follow manufacturer recommendations and guidelines with regards to the frequency of a full calibration.
Additionally, you will need to “Zero” the instrument in fresh air prior to each use. Do not make the mistake of zero adjusting in an atmosphere that you are not certain is fresh air. Many accidents have occurred when a user has zero adjusted the instrument in an environment that really had some level of toxicity.
There are some great options to make this a very simple and automated process. Docking stations with automatic calibration ensure that the instruments are always fully charged and calibrated at all times. This is especially interesting for companies that have multiple gas monitors to track, maintain and calibrate.
What is a “bump” test?
A “bump” test simply involves exposing the sensors to a known concentration of gases in order to make sure that the sensors detect those concentrations correctly.
What is the difference between a “bump” test and a calibration?
A bump test only makes sure that the sensors are working properly within a certain margin of error while a full calibration includes adjustments to account for and rectify the degeneration that many sensors experience as they get older.
Portable vs. Fixed Systems
When would a fixed system make sense?
There are many instances where it does not make sense to have every employee walking around with a gas monitor clipped to his or her belt all day long. When normal atmospheric conditions prevail but there is the potential for exposure to a certain chemical(s) or substance(s) it makes sense to set up a fixed system to detect when a problem arises. Food processing plants that freeze their product are a good example here. Food processing uses Ammonia in cold storage. Ammonia is highly toxic even in very minute quantities. A fixed system that would detect a leakage is a very effective way to monitor the plant to make sure that no one is ever at risk. Sensors placed at strategic locations and set to detect very small amounts of ammonia will alert operations to any leak that might be present. There is no other atmospheric hazard present so there is no need to monitor for other potential problems.
Parking garages are another great application for fixed systems. Because cars are going in and out all day, there is a potential for CO to built up in areas that might not be properly ventilated or where the ventilation might not be working properly. Strategically located CO monitors would alert operations to a buildup of CO that might become a problem.
The two most common gases and what you need to know about them
Carbon Monoxide is the leading cause of accidental poisoning in America. CO is produced when combustion is present and is a result of incomplete combustion from cars and other combustion engines. Even small amounts of CO can be harmful and fatal. CO bonds to the blood cells in the human body and block the transport of oxygen essentially starving the body of O2. Because CO is colorless and odorless and has almost the same density as air it often isn’t detected until it is too late.
H2S is produced by bacterial breakdown of organic material such as sewage, compost, sediment, etc… It is highly toxic even at low concentrations. Though colorless, it has the smell of rotten eggs at low concentrations (1-100 PPM) but that distinct odor decreases as the concentration increases (over 100 PPM). It is heavier than air and tends to displace oxygen. Even at concentrations as low as 500 PPM it can be fatal within 30 minutes to an hour.
Types of Gas Detectors
Catalytic Sensors (also known as “Hot Bead” sensor)
This sensor ionizes the combustible gas and measures the change in resistance that results from the change in temperature.
CMS (Chip Measurement System)
This method is similar to the detector tubes below, except that it utilizes an electronic optical reader.
This consists of Individual glass tubes through which the air is pulled. In the tubes is a reagent that changes color as it reacts to the specific chemical.
This sensor utilizes electrodes. The gas passes through a gas permeable membrane to produce a chemical reaction with the electrode which results in an electric current. This current is then read and measured in order to identify the compound as well as the concentration.
Flame Ionization Detector (FID)
The instrument burns the sampled gas using a hydrogen flame. An electrode collects the organic compounds and measures the generated current.
Infrared Detectors (IR)
This sensor measures light, more specifically the absorption of infrared light to identify carbon dioxide O2)
Photo Ionization Detector (PID)
This sensor measures VOCs (Volatile Organic Compounds) using ultraviolet light to ionize the gas.
Sample Collection and Analysis
This method draws air through a sampling media. The media is then analyzed in a lab to determine contaminants and levels.
What factors should I take into consideration when purchasing or renting a gas monitor?
- Do you need datalogging? Do you only need to have the alarm go off if there is a problem or do you want a complete record of all levels present at all times? Datalogging comes in several different formats with some only recording the data for the past 30 minutes and others recording for much longer. Find out which one you will need and make sure that your instrument can do what you need it to.
- How often am I going to use the instrument? Are you only going to use it a couple of times a month or daily?
- Do I want rechargeable batteries or disposable batteries to power the instrument? If one has its advantages and drawbacks and you need to be sure and make sure that the one that you choose will match the application you will have for the instrument.
- Do I know what I am looking for or will there be unknown elements present? Entering a certain room where there might be a CO gas present is a completely difference job than entering a sewer system where any number of potential hazards might be present. In the former case a single gas monitor to detect CO might be all that is needed, in the latter case a four, five or six gas monitor will probably required to ensure the safety of the worker.