Developments in gas detection
Gas monitoring instruments used by occupational and environmental health and safety (OEHS) professionals have come a long way in improvements since the days of analog monitors designed to warn coal miners of the presence of methane gas. They are advanced to the point where the instruments are chock-full of exceptional features and functionality, much of which comes standard with the product. New or improved technologies have helped to raise the bar, as well as market expectations, resulting in better products and more choices.
Gas detection and monitoring systems are used as safety devices to alert workers of the potential danger of poisoning by toxic gas exposure, suffocation due to lack of oxygen, and fire or explosion caused by combustible gases. Although the gas detection market has matured over the years, it has become increasingly technologically savvy. Advancements have made yesterday’s “whistles and bells” now economically feasible even in compliance-driven four-gas monitors. Today’s portable gas detectors include advanced sensor options, microprocessor-driven electronics, next generation signal processing, enhanced data manipulation and storage and state-of-the-art battery choices.
Any discussion about gas detectors must begin with the heart of the instrument – the sensors. Sensor technologies most commonly used for confined space and personal monitoring are very mature and include catalytic diffusion for combustible gases and electrochemical sensors for oxygen and toxic gases. However, other sensor technologies, such as photo-ionization and non-dispersive infrared (NDIR) have become more cost effective to produce and thus are becoming more common for certain applications.
Over the course of the years, sensor miniaturisation and advanced signal processing have enabled manufacturers to use a mix of sensor technologies in the same package to accommodate the best total solution for environments with multiple gas hazards. However, sensor technologies are not suitable for all gas types and cross-interferences may inhibit some sensor combinations. Any questions regarding suitability for use should be addressed with the instrument manufacturer.
Multi-gas instruments with interchangeable sensors provide flexibility of monitoring for a variety of applications. This adaptability reduces operating costs and training expenses. “Smart” sensors come pre-calibrated and include on-board data specific to that particular sensor, including sensor type and measuring range, calibration set points and unique serial number identification. Current “plug and play” field-changeable sensors are a vast improvement from past designs and reduce downtime associated with instrument and sensor service.
Another feature, sensor over-range protection, uses the power of the microprocessor and the sensor signal processing to electronically shut off power to the sensor after reading high levels of gas, which extends the life of the sensor, ensures sensor integrity and lowers replacement costs.
User configurable operating system
Most monitors of today offer common features such as a dot matrix display of real-time monitoring data of all installed sensors, audible, vibrating and visual alarm signals, and data logging of gas exposure data. User-friendly programming of the operating system allows managers to “tune” the instrument to their specific applications for display choices, alarm parameters, calibration settings, data management and other instrument operations. Password-protected codes restrict users from tampering with settings established by industrial hygienists or safety managers.
Advancements in LCD display technology offer options well beyond what older 8-segment LED displays could provide. Improvements in the user interface of consumer products, such as cell phones, have spilled over into gas monitoring instrumentation. Gas detectors display as much, or as little, information as deemed necessary. Worker efficiency and skill level may determine a manager’s decision to activate a text-only vs. readings mode. A “go/no-go” text only mode provides minimal display data while real-time readings of all gases simultaneously allow the operator to view all sensor readings at a single glance. Some instruments have the ability to activate a text-only display for the end user while at the same time having the more advanced features working in the background for industrial hygiene uses. Newer graphic displays with icon-driven menus allow a multi-lingual workforce to use one common instrument, minimising training issues associated with language barriers.
STEL /TWA calculations and peak readings
One of the main keys to the progression of gas monitoring equipment centres on their ease of use, in particular, relating to the calculation and documentation of data that is collected through industrial hygiene functions. Short Term Exposure Limits (STEL) and Time Weighted Average (TWA) readings are calculated real-time, providing managers with precise measurements for occupational health assessments. A peak / hold function allows professionals to track peak exposures during job functions at the end of a work shift or after a monitoring incident has occurred. This feature can provide the tracking of workers’ gas exposures or provide useful evidence during incident investigations without the complexity of logging data. This is valuable tracking information the instrument can provide to OEHS professionals to maintain accurate records and documentation so they are within safety regulations.
Data logging of gas exposure data
In addition to STEL and TWA, data logging typically captures each gas sensor reading, temperature, instrument ID, and time and date of the sample. This information is important not only for the immediate health and well being of workers who may be exposed to atmospheric hazards, but having the hygiene information documented will allow operators to make educated and calculated decisions on how to eliminate gas hazards from the work area, and keep it safe for workers. Previously an optional additive, data logging features typically are included now in the base price of a monitor. Microprocessor driven designs allow built-in or removable data storage to provide days, weeks or even months of extended-shift, continuous data recording before exceeding memory capacity. Through easy operating system setup, managers can program data logging intervals, pause and resume choices, overwrite capability, and automated event logging. Accompanying downloading and graphing software provides an analytical tool for the industrial hygienist or OEHS manager.
Data input for user and site ID recording
A data input element further enhances the logged data to imprint the data logger with user and location/site information automatically. One benefit this provides is the means for validating gas survey data through identification and time/date stamp of each monitored site, user, and gas measurement/ exposure record. Field data input can be achieved manually or be automated by scanning bar codes or memory devices carried by the user or attached to the site being monitored.
Interchangeable battery choices
Most monitors offer a variety of power sources to provide round-the-clock monitoring capabilities, as well as alternate battery power available at a moment’s notice. The latest rechargeable battery technologies, such as Lithium-Ion, do not have “memory” problems found in older Nickel-Cadmium batteries. New non-rechargeable Lithium batteries are typically smaller in size, lower in power consumption, and also provide extended instrument run-time allowing for lasting power throughout long shifts for continuous worker protection.
Alarms – audible, visual and vibrating
Audible, visual and vibrating alarms provide the user of the equipment with an indication that dangerous conditions exist. The combination of all three types of alarms built-in to the instrument is possible with the new power options available today. It is important that the audible alarms are intense, the visual alarms bright and able to be seen from a wide angle and that a vibrating alarm is strong so that they grab your attention immediately when an alert is necessary. Usually a selectable option within the operating system, high alarm levels “latch” on to ensure a warning is not ignored and the user acknowledges the danger. Latching alarms cannot be turned off unless the atmosphere is clean and conditions are safe.
Simplistic calibration options
Contrary to what you may have been led to believe, there is no electronic method for compensation or a full self-calibration of sensors that will correct the effects of drops, shocks, or extreme exposures to gas or temperatures. When you think about a typical industrial environment and the multiple workers that carry the monitors into confined spaces, you realise that there is a good chance that they will be bumped or dropped, stored in a hot truck, or hit with a strong blast of gas. These factors affect the sensor’s ability to react to gas at the maximum accuracy possible.
The importance of regular instrument calibration is critical to prevent inaccurate readings. Using a known concentration of test gas, the instrument reading is compared to the actual concentration of the gas and then adjustments are made to the readings if they do not match. Today, most direct-reading instruments offer quick, push-button calibration with electronic corrections in place of older potentiometer adjustments.
With the latest operating systems, many instruments provide the option to track and display the last calibration date and/or the next date the instrument is due for calibration. This feature allows the user to be certain that the instrument has been calibrated and maintained within an acceptable time frame.
Automated instrument maintenance and calibration stations
Automatic instrument management systems have quickly become a very popular trend in the gas detection market. These systems are designed to automatically maintain the instruments by bump testing, calibrating, downloading hygiene data, testing integrity, and charging the instruments automatically with no need for end user intervention.
What makes these systems so popular? The fact that the end users do not need to do anything but set the instrument into a cradle and walk away is appealing to everyone. With companies downsizing, instrument maintenance sometimes suffers. There are fewer instrument specialists available to maintain fleets. These automated systems are ideal solutions for such a situation. One person does not have to manually maintain all the instruments and documentation. The system can be set up to automatically manage and maintain the fleet with little or no user intervention. With automatic record keeping built into the systems, all the required documentation is safely stored on computers and can be printed at any time. Databases manage the data storage and allow for easy searches on calibration histories and hygiene data.
The evolution of automated instrument maintenance systems have afforded us the opportunity to now utilise two way wireless and or Ethernet connectivity to link up to 100 standalone instrument docking modules from remote locations anywhere in your facility, across the country or around the world. This connectivity allows information from each station or site to be relayed back to one central database, allowing for a total, centralised, instrument management program.
Today’s life-preserving gas monitors are technically advanced and purpose-built with features that are designed to deliver superior performance and longevity. Not only are the instruments built with more safety-conscious features, they have many options that ultimately save time and money. OEHS professionals should look forward to continued improvements in the development of gas detection instrumentation, as expectations push for smaller, lighter, faster, and better products from manufacturers.
Sidebar – A paradigm shift in gas detection
Automated maintenance systems for portable gas detectors are designed to automatically maintain the instruments by function or “bump” testing, calibrating, downloading hygiene data, record-keeping and charging the instruments with no need for end user intervention.
Patented technology takes the system a step further, by incorporating a two-way data port between gas monitors and Docking Stations TM1 , which can download information from and upload information to the instruments. Not only is this a real asset for viewing and maintaining instrument records on a global basis, it also allows users to centrally configure the instrument settings. Each instrument can be standardised with the same parameters to guarantee consistency in alarm values, calibration frequency, and calibration gas across the entire company. The two-way communication also allows the Docking Station software to acknowledge a calibration due date by initiating calibration upon docking, or override the instrument setting for “bump” test schedule.
With a smart instrument at the core of the system, visibility into a network of these devices becomes a powerful management tool. The beauty of consolidated data is centralised control from one vantage point. Add the power of the largest data network, the Internet, and there is an opportunity for remote management above and beyond corporate networking capability – the option for ‘smart services’ becomes a reality. Bi-directional communication between the Docking Stations and a remote service centre provides the ability to send software updates, requests for diagnostics, or alerts to the users, instruments or Docking Stations through the control centre. It’s one thing to engage in a repair or maintenance contract with scheduled service intervals, but it becomes extremely efficient and cost reductive when the service provider is privy to data that will allow pre-emptive scheduling of maintenance and parts replacement on an as-needed basis.
The obvious advantage of using a third party to oversee the health and maintenance of the gas monitoring fleet is that you don’t have to. Additional advantages of using the manufacturer of the smart instruments as the service provider include immediate attention to software modifications, supply chain management, and direct access to approved replacement parts.
A new set of gas monitoring ‘smart’ instrument network services called iNet TM , offered by Industrial Scientific Corporation (Oakdale, PA), provides an alternative way of managing gas monitoring. Using the Internet, instrument data is collected and analysed to ensure that the equipment is in optimum working condition. Through patented technology and remote twenty-four hour monitoring, the status of the gas monitors, calibration gas condition, sensor performance and instrument calibration is reported over the Internet and is available as a service on a subscription basis. Notification of component or instrument failure, low or expired calibration gas, and calibration documentation is provided in a custom status report delivered weekly via e-mail.
If customers wish to take it one step further, the service can include data warehousing of instrument readings, automatic initiation of repair parts delivery, or the dispatch of instrument repairs/replacements. A full-service solution is available to customers who want to outsource their gas monitoring maintenance program and receive on-site service visits for seamless repair work. Any or all pieces and parts of the all-encompassing gas monitoring program can be bundled as a monthly service fee to alleviate the internal burden and turn it over to the experts who can provide that core competency.
Under a four-year contract, customers can benefit from a consolidated monthly usage fee covering any or all of the following services:
- Lease of single or multi-gas instruments in any combination
- Installation and setup of Docking Stations and server, including testing of system
- Training on instrumentation and system subsequent to installation
- 24/7 monitoring of instrument fleet via the Internet
- Weekly system status report showing instrument and component status and details
- Automatic notification of instrument or Docking Station malfunction
- Automatic initiation of any service actions required
- On-site repair service where mobile service coverage is available
- Automated instrument exchange if preferred over on-site repair service
- Automated parts delivery if self-service is preferred
- Replacement/Repair parts, freight, labour & travel expenses included depending on selected service
- Automated calibration gas replenishment when cylinders are empty
- Asset tracking of instruments by serial number
- Secure off-site storage of all data
This new way of managing a gas detection program modifies the current business model by providing a ‘smart’ service-based solution. Under this new paradigm, the supply, calibration, maintenance, repair and record-keeping of an entire gas detection fleet can be managed remotely by the experts, leaving the management of your core business to you.
Published: 10th Oct 2007 in Health and Safety International