In today’s gas detection market, occupational health and safety pros have many choices when purchasing a single or multi-gas monitor. One major factor to consider when choosing is whether the monitor will be used as a personal monitor to protect workers in the field or for industrial hygiene and monitoring purposes.

In what application will the portable gas detection equipment be used? Will the monitor be worn continuously throughout the day to provide personal safety monitoring, or will it be used intermittently to gather samples, for confined space entry, or for other industrial hygiene needs?

Each of these situations requires specific features in the gas monitoring equipment. In this article, we will compare the needs of personal monitoring versus the needs of industrial hygiene.

Personal safety considerations

When selecting a personal safety single or multi-gas monitor, evaluate the following factors:

Comfort. Since the monitor will be worn between 8-12 hours a day either on the user’s belt, overalls or hardhat, select a monitor that can be worn continuously throughout a work shift. Its size and weight matter. A variety of clips and carrying cases should be readily available so the user can attach the instrument to their clothing, in a manner they’re comfortable with.

Alarms. Personal safety monitors should have a full feature set of alarms including low, high, TWA (time weighted average), STEL (short-term exposure limit) and low battery warnings to alert the user of any unsafe condition. When the instrument goes into alarm, loud audible, bright visual and internal vibrating alarms alert the user that there is a hazardous condition.

Displays. LCD displays to show the real-time readings allow workers to see the gas concentrations and monitor battery life. LCDs can also be used for selecting menu items, setting alarms, and for user feedback for bump tests and calibration information.

Sampling pumps. For applications in which a remote sample may be taken, whether occasionally or continuously, remote sampling pumps can be used. These accessory pumps can be internal to the instrument, which will affect size and weight, or external and detachable to the unit, offering flexibility.

Battery. Newer battery technologies such as lithium-ion offer extended runtimes, typically in excess of 24 hours of continuous operation on a single charge. Lithium-ion batteries have a higher charge density than other battery technologies, allowing manufacturers to use smaller batteries while achieving longer runtimes. Finally, lithium-ion batteries do not exhibit the memory effects that older nickel cadmium batteries were susceptible to.

Maintenance. With the everyday wear and tear these instruments face, maintenance is a major consideration. Maintenance tools range from bump test and calibration stations, to complete instrument management systems. Such systems automate the bump/calibration routines, reducing time and money and ensuring the instrument is in proper working condition.

Industrial hygiene considerations

Monitors that are used for industrial hygiene/monitoring applications share some of the same desired features as personal protection instruments, but there are additional features that should factor into your decision-making process.

Visuals. The instrument should be equipped with a large graphic LCD display. Used for a variety of purposes, the display allows the industrial hygienist or safety officer to take readings for confined spaces or gas samples and instantaneously see them. Each working sensor installed in the instrument and corresponding gas reading should be displayed simultaneously on the LCD. Visual menu-driven operating systems offer the user more features that are easy to access and program.

Alarms. User adjustable low, high, STEL and TWA alarms are typically standard. When any of these alarm levels are reached, onboard audible and visual alarms alert the user of a hazardous condition. Programmable STEL and TWA time bases are also offered.

Durability. Generally, full-featured multi-gas monitors are used daily by safety officers to check for emissions, leaks and confined space entry. Facing some of the harshest and dirtiest environments in industry and likely to be dropped, sprayed with water, kicked, run over, submerged, exposed to dust or thrown into the bed of a truck, these instruments must be durable and reliable.

Remote sampling. The user should be able to use a remote sampling pump to draw a sample from either a well or pit, or extend a probe to check pipes for leaks or emissions. Pumps are available internal to the instrument or externally attached to the instrument. A detachable pump can be easily removed should it stop working and the worker will still be protected by using the instrument in a diffusion mode. The parasitic style pump eliminates the need to either replace or recharge the batteries in the pump.

Datalogging. Being able to capture each gas reading, temperature, instrument user ID, site ID and time/date of a sample is valuable information that most safety officers and hygienists require. User-selectable logging intervals from one second to up to five minutes are available. Some special features such as “log on alarm” allow the user to capture data only when the instrument goes into alarm, which reduces the amount of memory used. More advanced datalogging systems let the users know how long the datalogger has been turned on, or how long until the datalogger’s memory is full. Data can be extracted from the instrument and viewed or saved on a PC, allowing for analysis later as well as recordkeeping.

Maintenance/management. Instrument docking systems are available that allow users to charge the instrument, download hygiene data, schedule routine calibrations and bump tests, and run diagnostic tests. More advanced systems allow users in multiple locations to share data over networks. This enables companies with multiple locations, including around the world, to manage and store all of their instrument data in one centralized location. Being able to schedule bump testing and calibration reduces maintenance time and costs for the end-user. These functions can be programmed to occur automatically on a specific day and time. This allows the user to “dock” their instrument at the end of the work day and come in the next day knowing that the unit has been properly calibrated, tested and charged.

The next time you are faced with the decision to buy a gas monitor, take a few moments to consider the application, environment, maintenance, end-user and the features of the product. This will ultimately lead you to the best instrument for the job.

SIDEBAR: Maintenance a must

Whether you are using a gas detection instrument for personal monitoring or industrial hygiene, proper maintenance is strongly recommended. Bump testing the instrument prior to each day’s use with a known concentration of gas ensures that the sensors are responding. Regularly scheduled calibrations ensure that the instrument is accurate and working properly.