Stocking your gas detection toolbox
November 1, 2007
Every weekend, thousands of do-it-yourselfers journey out to their local hardware store to purchase equipment for their weekend task, be it a bathroom remodel, lawn maintenance, or simply to replace a light bulb. Upon returning home, the weekend task gets underway. However, while working on the chore at hand, many times the proper tool is not in the toolbox or in sight; this is something that almost everyone can relate to.
What’s the solution? Usually, you grab the closest thing that resembles the tool you need and force it to work for your application. Many times these actions result in lost time, damage to the project, a smashed or broken thumb, or sometimes success! But if the proper tool had been used from the onset, the project would have been completed faster, safer and with higher quality.
A gas detection program is very similar to weekend chores. A properly designed gas detection program consisting of the right tools for the job will lead to a safer, higher quality and more productive workplace.
What are the proper tools for a gas detection program? Quite simply, these are the tools needed to safely protect workers and equipment within and around your facility. These tools consist of portable gas detection, fixed mounted gas detection, temporary monitoring, control systems, and possibly fence line monitoring.
Portable gas detectionWithin any gas detection program, there can be a mix of single-gas and multi-gas portable instruments. The key to any portable gas detection program is to first identify what the gas hazards are, and then decide how to protect workers against them. Many times, single-gas monitors are used for full-time personal protection of workers. These instruments contain a sensor capable of detecting the hazardous gas at hand, and are worn by workers within the facility at all times.
If more than one hazardous gas is present, or if workers are doing confined space entries, multi-gas monitors are used. These instruments can contain from two to six sensors and are capable of displaying all of the gas concentrations simultaneously. Multi-gas instruments typically allow the data to be stored and transferred to a PC for further analysis.
When choosing multi-gas instruments, a few options are available, including sample pumps, diffusion instruments, and sensor offerings such as a photoionization detector (PID). Assess field functionality when deciding on instrument options. Quite simply, how will you use this instrument? If you must draw a sample from a vessel or confined space, then you should use a pump. If unknown volatile organic compounds (VOCs) could be present, then a PID option is a good choice.
Fixed mounted gas detectionIn almost any industrial process, there are hazardous gases used in the process or released as by-products of the process. Fixed mounted gas detectors are a good choice to monitor specific areas of a plant where there is always a threat of a hazardous or combustible leak. Use these permanently mounted gas monitors to protect workers within the area of the monitors, as well as to protect the equipment and the processes.
As with portable instruments, the most important aspect of fixed-point detection is to identify the potential gas hazards and locate the sensors in an area where they will be able to detect the leak. There are a number of options on the market today to help with the location of sensors. Manufacturers offer sensors that you can locate remotely from the main units, allowing you to place the sensor closer to the potential leak point. Some manufacturers even offer multiple sensors in a unit, reducing costs as well as increasing the coverage of the sensors.
Control systemsWhen high levels of combustible or toxic gases are detected, something needs to happen, be it an alarm sounded, a process stopped or a process started. This is the job of the control system. Each fixed mounted gas sensor is connected to a control system that analyzes the gas concentrations of each sensor, and then determines if an action needs to be taken.
There are a number of control systems available today. Control systems can be as small as one to four sensors, or they can have hundreds of sensors as inputs. Base your selection of control systems on the desired outcome if a leak is detected. In some cases, the desired outcome is to maintain a Safety Integrity Level (SIL) within the facility. In these special cases, you should use a safety control system as part of the control system design.
Temporary monitoringFacilities often overlook the temporary monitoring aspect of gas detection programs or use the wrong “tools” for this job. Many times, unexpected maintenance or situations occur where a facility needs to temporarily place gas monitoring in an area while work is being done. Sometimes portable gas monitors are used. More often than not, no gas detection is used.
A number of “temporary” area monitors are designed specifically for these instances. These self-contained devices can detect from one to five different gases. Internal batteries allow the instruments to run for extended periods of time â€” days instead of hours. Loud audible and visual alarms built directly into the device alert everyone in the area that a hazardous condition is present.
If extended use is required, you can use intrinsically safe power adaptorsa. Some products available today are powered from solar devices. You can deploy these temporary monitors for extended periods of time in remote locations such as pipelines. Users can extract information via remote Web access or GSM/GPRS interface. You cannot use temporary monitors on a day-to-day basis, but when needed, they are the correct tools for the job.
Perimeter and fence line monitoringMore often than not, we are concerned about what is happening within the facility and tend to overlook what is leaving the facility and going into surrounding communities or industries. This is where perimeter or remote monitoring systems are an extremely useful tool. You can place these devices permanently around a facility, or temporarily locate them in work areas.
The main purpose of these instruments is to detect when a gas leak is moving out of the facility and into the surrounding communities. When leaks are detected, the facility can sound alarms and notify response teams to evacuate an area, or take action where the release is going.
Maintaining your toolboxWhat good is having a tool to use if it doesn’t work? As with any tool, all gas detection equipment within your program requires proper maintenance. Maintenance includes testing and calibrating sensors, pumps and alarms, as well as visually inspecting the equipment and filter elements to ensure that they are not clogged or dirty.
To help with maintenance, automatic calibration and test stations are available. These devices automatically test, calibrate and diagnose any issues that may occur with the equipment. Some manufacturers offer gas detection maintenance and management programs to take these burdens off of the end user. Who better to maintain and manage a gas detection program than the manufacturer of the equipment?
Any good workshop has a mixture of tools and equipment to tackle weekend projects. A gas detection program should contain a mix of different types of monitors and sensors, designed for the specific task at hand. Next time you reach for your hammer, or your portable gas monitor, think to yourself, “Is this the right tool for the job?”