Page 49 - International safety guide for oil tankers and terminals
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HAZARDS OF PETROLEUM




                                  H 2 S Concentration
      ---ใช้เพื่อการศึกษาเท่านั้น---
                                                                        Physiological Effects
                                (ppm by volume in air)
                                   0.1 – 0.5 ppm        First detectable by smell.
                                                        bladder. Breathing will stop and death will result if notย์นาวี
                                      10 ppm            May cause some nausea, minimal eye irritation.
                                      25 ppm            Eye and respiratory tract irritation. Strong odour.
                                   50 – 100 ppm         Sense of smell starts to break down.
                                                        Prolonged exposure to concentrations at 100 ppm induces
                                                        a gradual increase in the severity of these symptoms and
                                                        death may occur after 4–48 hours’ exposure.
                                     150 ppm            Loss of sense of smell in 2-5 minutes.
               งานห้องสมุด ศูนย์ฝกพาณิช
                                     350 ppm            Could be fatal after 30 minutes’ inhalation.
                                     700 ppm            Rapidly induces unconsciousness (few minutes) and
                                                        death. Causes seizures, loss of control of bowel and

                                                        rescued promptly.
                                     700+ ppm           Immediately fatal.
                             Note: Persons over-exposed to H 2 S vapour should be removed to clean air as soon as
                                   possible.
                                   The adverse effects of H 2 S can be reversed and the probability of saving the
                                   person’s life improved if prompt action is taken.
                                                                          ึ

                                    Table 2.1 – Typical effects of exposure to hydrogen sulphide (H S)
                                                                                               2


                                        Vapour Monitoring
                                        Exposure levels in all work locations should be monitored by using
                                        suitable instrumentation for detecting and measuring the concentration of
                                        the gas.

                                        High concentrations and the corrosive nature of the gas can have a
                                        damaging effect on many electronic instruments. Low concentrations of
                                        H S over time can also have a damaging effect on electronic instruments.
                                         2
                                        Detector tubes should therefore be used if it becomes necessary to
                                        monitor a known high concentration.

                                        Bunker fuel tanks should be monitored prior to, during and after
                                        bunkering. If H S has been detected, the bunker tank should be
                                                     2
                                        periodically tested. Although the concentration in the vapour space can
                                        be successfully lowered by forced air ventilation, it often increases again
                                        when the bunker fuel is heated, transferred or agitated by other means.

                                        Bridge, control room, accommodation and engine spaces should be
                                        monitored if H S may be present. Ventilation systems should be operated
                                                     2
                                        as far as possible to prevent H S vapours entering the accommodation
                                                                   2
                                        and engine spaces. Low concentrations of H S over time can cause
                                                                                2
                                        discomfort to personnel.
                                        The use of personal H S gas monitoring instruments for personnel
                                                            2
                                        engaged in cargo operations is strongly recommended. These
                                        instruments may provide either a warning alarm at a pre-set level or an
                                        H S reading and an alarm. It is further recommended that the alarms be
                                         2
                                        set at a value of 5 ppm. Personnel should always carry personal monitors
                                        when working in enclosed spaces, gauging, sampling, entering a
                                        pumproom, connecting and disconnecting loading lines, cleaning filters,




                                                   © ICS/OCIMF/IAPH 2006                                        15
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