Monitoring, flame arrester

If appropriate, eliminate flame arrester or use parallel switchable flame arresters with flow monitoring... 

Pressnre taps are often specified on each side of an in-line flame arrester for checking the pressnre differential across the arrester while in service. The taps and instmment installation mnst not provide a flame bypass aronnd the flame arrester. By monitoring pressnre drop, fonling or plngging may be detected early, if there is a snfficient vapor flow rate. 

One of the more effective preventive measnres is flame arrester monitoring, which will be discnssed in Section 5.3.18. 

Monitoring the pressure drop of a dry type flame arrester is advisable to determine if the arrester is plugging. 

Temperature monitoring of a flame arrester to detect a stabilized flame (endurance burning) should be provided if it is expected that this may occur, or if such an event has already occurred in the past. 

To ensnre reliahility, dry-type flame arresters shonld he inspected on a regular basis, as mentioned previously. Also, as discussed in Section 5.3.18, it is often the pracdce to provide pressure drop and temperatnre instm-mentadon to monitor the flame arrester condidon in service. This will provide indicadon of impending problems dial can affect the performance of the flame arrester. 

Elydranlic (liquid seal) flame arresters require attention on a regular basis similar to that for dry-type flame arresters. It is critical to ensnre that the liquid level is at the required height, and level instmmentation with alarms is recommended. Automatic addition of makeup liquid (to replace evaporation and entrainment losses) is desirable. Temperatnre instrumentation is also recommended to monitor the occurrence of sustained burning (a stabilized flame). See Section 5.3.18 for more details. 

Continnons monitoring of pressure drop and temperature should be carried out. Pressure drop should be monitored if fouling and subsequent plugging is suspected or has previously occurred. Temperature monitoring should be provided if it is possible for a standing flame to occur on the flame arrester face and subsequently destroy the element (see Chapter 7). 

Monitoring The differential pressure across the arrester element can be monitored to determine the possible need for cleaning. The pressure taps must not create a flame path around the arrester. It can be important to provide temperature sensors, such as thermocouples, at the arrester to detect flame arrival and stabilization. Since arrester function may involve damage to the arrester, the event of successful function (flame arrival) may be used to initiate inspection of the element for damage. If the piping is such that flame stabihzation on the element is a realistic concern, action must be taken immediately upon indication of such stabihzation (see also Endurance Burn ). Such action may involve valve closure to shut off gas flow. 

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