Hydrogen Sulfide Alarm Settings

In february 2010 the american conference of governmental industrial hygienists acgih adopted a new threshold limit value tlv recommendation for h 2 s lowering the 8 hour twa to 1 0 ppm.

Hydrogen sulfide alarm settings.

Chlorine plants hydrogen sulphide offshore. Hydrogen sulfide and hydrogen sulfide monitoring instrumentation. The third chart compares the performance of the gfg 2cf hydrogen nulled sensor and a standard gfg 4cm co sensor exposed to 200 ppm co calibration gas. No doubt 5 ppm should be one of the alarm set points on a dual alarm unit and should be the setting on a single alarm equipped instrument.

Lel ch4 0 to 60 and 0 to 3 0 by vol ch4. Guidance currently exists on the hse website for setting alarm levels for predominantly flammable gas detectors. All alarm set points are field adjustable over the full range of the sensor exceptions. The post below is from a real client case and shows how hydrogen gas can trigger these alarms and potentially become an explosive hazard.

You can adjust the alarm trigger point to suit your environment. Carbon monoxide alarms are vital pieces of safety equipment used to protect workers and residents from poisonous carbon monoxide gas. Monitoring hydrogen sulfide h 2 s to meet new exposure standards st 9660 2007 abstract in order to better protect workers from exposure to hydrogen sulfide h 2 s acgih modified the threshold limit value tlv for this chemical in 2010. High alarms are based on 2 times osha pel values.

Provided standards exist all alarm settings are based on the following. Similar guidance does not exist however for toxic gas detectors although alarm levels are specified for a limited number of gases in specific industries e g. A calibration check must be performed on the detector before each use to verify that it is working properly. The unit features one person calibration and can virtually self calibrate by simply activating a magnetic switch and applying gas.

This white paper presents information on the health effects of h 2 s. The check requires a regulator tubing and cylinder sold separately. While the hydrogen nulled sensor takes a little more time to recover after exposure the time to alarm is virtually the same for both sensors. Depending on individual circumstances an alarm 1 setting of 2 and alarm 2 setting of 5 seem appropriate.

In the past the most widely recognized occupational exposure limits for hydrogen sulfide h 2 s have referenced an 8 hour twa of 10 ppm and a 15 minute short term exposure limit stel of 15 ppm. When these detectors sense high levels of hydrogen sulfide they alert you with an audible alarm warning light and vibrating alarm. But did you know that hydrogen gas from charging batteries can set off the alarms as well.