Continuous Toxic Gas Monitoring

A continuous gas-detection system is required by Uniform Fire Code Article 51 and Article 80, where toxic or highly toxic gases are stored, dispensed or used. The system must continually monitor use areas for the potential presence of fugitive gases. These systems must be designed in accordance with  

A continuous gas-detection system shall be provided to detect the presence of gas at or below the permissible exposure limit or ceiling limit. The detection system shall initiate a local alarm and transmit a signal to a constantly-attended emergency control station (ECS). The alarm shall be both visual and audible. The gas-detection system shall be capable of 

Automatic shutdown of the toxic gas supply lines is required. The following code sections address the requirement for automatic shutoff valves  

Sensor Locations. The codes do not specify the exact location of gas sensors inside the feb area they simply state that the gas must be detected. Extremely high air movement rates in the cleanroom play a major role in the selection of sensor location and spacing. 

Control, Signaling, and Levels of Detection. We recommend that two levels of detection be provided, a low warning level set at 1/2 TLV (threshold limit value) and a high alarm level set equal to TLV (code-required). If the high level is reached, an alarm is sent to the ECS, a distinct toxic gas evacuation signal must be broadcast locally throughout the area, and the detected gas supply line must be automatically shut off. 

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Today, numerous alarm and monitoring systems are required by codes. These include fire alarm, smoke detection, sprinkler system supervision, emergency (spill) alarm, and continuous toxic gas monitoring and detection systems. 

Most industrial hygiene air monitors in the semiconductor industry are used for flammable and toxic gas leak detection (see Ch. 11, Toxic Gas Monitoring). However, some facilities are also using continuous monitoring systems to ... 

Within the semiconductor industry a variety of continuous gas monitors are used (see Sec. 2.5 and Ch. 11, Toxic Gas Monitoring, for additional information). Historically, thesemonitors were primarily used to determine if a toxic gas leak had occurred, rather than actual measurements of breathing zone concentration of chemicals. Sample points for the monitors were located in exhausted enclosures as well as in potential release points in the clean room. 

One fact is for certain both gas detectors and toxic gas monitoring systems must continue to improve to keep pace with future revisions and additions to national, state, and local fire and building codes and modifications to environment, health, and safety regulations for effective and affordable monitoring and protection of personnel, environment, and facilities. 

NFPA 55, 7.9.2.1 NFPA 55, 7.9.6.5 NFPA 55, 7.9.6.6 4.2.11 Indoor compressed gas storage areas that are used to store toxic or highly toxic gases indoors shall be equipped with a continuous monitoring system that would provide warning of toxic gas concentrations that could present a hazard to life. 

Detector) with the standard four gases of a confined space monitor (Oj, LEL, and two toxic gas sensors) in one compact monitor with sampling pump. The MultiRAE Plus is quickly and easily changed from a sophisticated techiucian instrument to a simple text-only monitor. The same monitor can be used as a personal monitor, a hand-held sniffer, or as a continuous operational area monitor. The detector can be made wireless with the use of RAELink2. RAE Systems, Inc., www.raesystems.com, (408) 952-8200. Chvie 268... 

The primary purpose of a gas detection system is to continuously monitor an area for the presence of hazardous and toxic gases at or below a specific concentration limit, and if necessary, warn personnel through both visual and audible alarms prior to the onset of a life threatening condition. W... 

The use of FTIR (Fourier transform infrared) spectrometers as a continuous monitoring technique overcomes many of the problems associated in analyses of hot fire gases. FTIR offers an opportunity to set up a calibration and prediction method for each gas showing a characteristic spectral band in the infrared region of the spectrum. A European project, SAFTR, aims to further develop the FTIR gas analysis of smoke gases to be an applicable and reliable method for the determination of toxic components in combustion gases related to fire test... 

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