What’s so Important about my Monitors Measuring Range?

What is a Monitor Measuring Range?

Gas monitoring is usually measured in PPM range (parts per million), percentage volume or percentage of LEL (lower explosive limit) this enables Safety Managers, to ensure that their operators are not being exposed to any potentially harmful levels of gases or chemicals. Gas monitoring can be done remotely to ensure that the area is clean before a worker enters the area as well as monitoring gas through a permanently fixed device or body worn portable device to detect any potentially leaks or hazardous areas during the course of the working shift.  

Why are Gas Monitors essential and what are the Ranges of deficiencies or enrichments?

There are three main reasons why monitors are needed; it is essential to detect oxygen deficiencies or enrichment as too little oxygen can prevent the human body from functioning leading to the worker losing consciousness. Unless the oxygen level can be restored to a normal level the worker is at risk of potential death. An atmosphere is considered to be deficient when the concentration of O2 is less than 19.5%. Consequently, an environment that has too much oxygen in it is equally dangerous as this constitutes a greatly increased risk of fire and explosion, this is considered when the concentration level of O2 is over 23.5%. 

Monitors are required when Toxic Gases are present of which can cause considerable harm to the human body. Hydrogen Sulphide (H2S) is a classic example of this. H2S is given off by bacteria when it breaks down organic matter, due to this gas being heavier than air, it can displace air leading to potential harm to persons present and is also a broad-spectrum toxic poison.  

Additionally, gas monitors have the ability to detect flammable gases. Dangers that can be prevented through using a gas monitor are not only though inhaling but they are a potential hazard due to combustion. gas monitors with an LEL range sensor detects and alert against flammable gases.  

Why are they important and how do they work?

Measurement or Measuring Range is the total range that the device can measure in normal conditions. The term normal meaning no overpressure limits (OPL) and within maximum working pressure (MWP).  These values are usually found on the product website or specification datasheet. The measuring range can also be calculated by identifying the difference between the Upper Range Limit (URL) and the Lower Range Limit (LRL) of the device. When trying to determine the range of the detector it is not identifying the area of square footage or within a fixed radius of the detector but instead is identifying the yielding or diffusion of the area being monitored. The process happens as the sensors respond to the gases that penetrate through the monitor’s membranes. Therefore, the devices have the ability to detect gas that is in immediate contact with the monitor. This  highlights the significance of understanding the measuring range of gas detectors and highlight their importance for the safety of the workers present in these environments.   

Are there any products that are available?

Crowcon offer a range of portable monitors; The Gas-Pro portable multi gas detector offers detection of up to 5 gases in a compact and rugged solution. It has an easy-to-read top mount display making it easy to use and optimal for confined space gas detection. An optional internal pump, activated with the flow plate, takes the pain out of pre-entry testing and allows Gas-Pro to be worn either in pumped or diffusion modes. 

The T4 portable 4-in-1 gas detector provides effective protection against 4 common gas hazards: carbon monoxide, hydrogen sulphide, flammable gases and oxygen depletion. The T4 multi gas detector now comes with improved detection of pentane, hexane and other long chain hydrocarbons. Offering you compliance, robustness and low cost of ownership in a simple to use solution. T4 contains a wide range of powerful features to make everyday use easier and safer. 

The Gasman portable single gas detector is compact and lightweight yet is fully ruggedised for the toughest of industrial environments. Featuring simple single button operation, it has a large easy-to-read display of gas concentration, and audible, visual and vibrating alarms.  

Crowcon also offer a flexible range of fixed gas detection products that can detect flammable, toxic and oxygen gases, report their presence and activate alarms or associated equipment. We use a variety of measurement, protection and communications technologies and our fixed detectors have been proven in many arduous environments, including oil and gas exploration, water treatment, chemical plants and steel mills. These fixed gas detectors are used in many applications where reliability, dependability and lack of false alarms are instrumental to efficient and effective gas detection. These include within the automotive and aerospace manufacturing sectors, on scientific and research facilities and in high-utilisation medical, civil or commercial plants. 

What are Area Monitors and how do I use one?

Outdoor leaks from storage tanks or pipelines are a particular kind of hazard. With many outdoor areas not housing permanent, fixed detectors. If you’re relying solely on a personal monitor, by the time it alarms, there is a possibility that you may be engulfed in a hazardous gas cloud. Therefore, a temporary early warning system between you and the potential source of a gas hazard has the ability to alert you to trouble coming your way.

What are Area monitors and where would they be used? 

Temporary Area monitors are usually rugged units that can be placed, stand-alone to monitor a small area or multiple units can be linked together via wired or wireless networking to create a perimeter defence of a larger area. Area Monitor devices help safety personnel protect their workers from gas hazards in situations, in addition to—or sometimes in substitution of—personal, portable gas monitors used as Personal Protective Equipment (PPE). Area monitors can be positioned to produce a guard between potential hazards and workers, to notify what they are heading into or what potential hazards are coming their way.  This occurs most often when work takes place outside of normal operations where the risks are higher and/or different such as special projects, construction, maintenance, shutdowns, temporary sites or rigs, etc. In this way, they can be used to form a barrier around a tank or along a portion of pipeline close to the location of work being carried out. Portable units can be easily deployed to provide fence line monitoring during maintenance, shutdowns or turnaround. The objective is to ensure that the devices are not so far apart that gas could pass between them undetected.  If a fixed system is being taken offline for maintenance a network of fast to deploy temporary area monitors is an ideal option to use in place of the fixed system until maintenance is complete and the system is brought back online. 

How do you use one? 

Units can be connected by cables. However wireless connection between individual area monitors is also available and avoids introducing a potential trip hazard. This could add significantly to an already risky task, for example, if working at height. Some wireless systems create a “self-healing” mesh network. In this case, should the wireless connection between two devices weaken, the network will automatically re-route communications via alternate enabled devices, creating a mesh type network allowing a more robust and efficient wireless network. 

The benefit from a wireless connection is that it is practical to use repeaters or extra units to relay alerts directly to the control room. Besides the gas alert signals, some detectors will transmit other faults i.e., the loss of signal, or “battery low” alarm. This programmed alert mode is often conveyed by a specific sequence of signals, such as the beacon and lights will flash for 3 seconds followed by 5 second pause which will be repeated until an operator acknowledges the alarm. 

Wireless temporary area monitoring allows for quick deployment whilst ensuring a high level of protection for workers in circumstances where the risks are tricky to monitor. Personnel working at height can be alerted to any gas hazards on the ground, or vice versa and the same alarm can be relayed to the control room by having an additional detector in the control room. The audible alarm is significantly louder than a standard portable and light sequence is brighter and flashes faster on the Detective+ unit when gas is detected. , whilst the sequence on other units in the network is slower. This differentiates the unit nearest the gas from the rest, so everyone is alerted to the location of the hazard. In contrary, to the benefits of this products, the configuration tends to be straightforward without additional hardware. The batteries in Detective+ are larger and last longer than conventional portables. All in all, these units offer a simple yet effective solution for protecting workers outside of normal operations. 

Crowcon’s Detective+ is ideal for temporary area monitoring while workers carry out a repair. Detective+ is portable and can be easily deployed to provide fence line monitoring during shutdowns or turnaround. If working on a cooling tower fin fan, Detective+ units are connected to other units (up to 70m away) via Detective Wireless modules, which eliminate the need for cabling between units. Detective Wireless uses the proven RICOCHET mesh network. In the unusual circumstance that the wireless connection between two devices weaken, the network will automatically re-route communications via alternate RICOCHET enabled devices and so ‘self-heal’. In essence, this creates a mesh type network allowing a more robust and efficient wireless network.

Read more about Area Monitoring  

Area monitoring – don’t be taken by suprise!


Outdoor leaks from storage tanks or pipelines are a particular kind of hazard. Many outdoor areas won’t have permanent, fixed detection. If you rely on your personal monitor, by the time it alarms, you could be engulfed in a hazardous gas cloud. A temporary early warning system between you and the potential source of a gas hazard can alert you to trouble coming your way.

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