NEBOSH HSE PSM COMPREHENSIVE EXAM UPDATED
QUESTIONS AND SOLUTIONS RATED A+
✔✔Safety integrity of SIS - ✔✔The average probability of a SIS performing its function
(under stated conditions for a certain period of time)
✔✔Saturated steam - ✔✔Steam that is still wet
✔✔3-5% - ✔✔What percentage of water remains in saturated steam?
✔✔Superheated steam - ✔✔Steam with temperature higher than its boiling point
✔✔Answer: Superheated steam - ✔✔Which type of steam is invisible?
✔✔Vacuum steam - ✔✔Steam created by reducing the operation pressure using a
vacuum pump, so the steam effectively below 100degs
✔✔Thermal expansion - ✔✔Hazard created by the expansion of pipelines or vessel as
a result of steam exposure
✔✔Answer: Thermal expansion - ✔✔What type of hazard is prevented by building in
flexibility or using bellows etc to allow material to expand?
✔✔Vacuum formation from steam - ✔✔Hazard created by steam producing
condensate, resulting in decreased volume
✔✔Vacuum breakers - ✔✔What measure is important to ensure there is sufficient
pressure within a system using steam to allow the condensate to be discharged?
✔✔Water Hammer - ✔✔Hazard resulting from water in a pipeline striking a fixed object
under high pressure
✔✔During start-up or under variable conditions - ✔✔At what stage of operation is water
hammer most likely?
✔✔Answer: water hammer - ✔✔What hazard is caused by water entrained in steam
being rapidly moved through a pipe (as condensate)?
✔✔Answer 2: Water Hammer - ✔✔What hazard is caused by steam rapidly condensing
due to being surrounding by cooler condensate, resulting in a massive change in
pressure due to loss of volume?
✔✔Thermal expansion, vacuum formation, water hammer - ✔✔What are three possible
hazards caused by steam?
, ✔✔Vacuum formation due to water - ✔✔Hazard caused by filling or emptying rate of
tanks/other vessels not being consistent with pressure
✔✔Vacuum breaker valve - ✔✔Measure which can be fitted to a tank so that the loss of
pressure in the head space above a liquid is compensated when the tank is being
emptied
✔✔Hydrostatic testing - ✔✔A means of checking for any leaks etc in pipelines or
vessels before start up or after alterations/maintenance
✔✔20-55 degrees - ✔✔What is the temperature range for legionella growth?
✔✔37 degrees - ✔✔What is the ideal temperature for legionella growth?
✔✔Legionella - ✔✔Hazard caused by cooling tower creating droplets of water in a
poorly maintained system
✔✔Vacuum formation, overload during improper hydrostatic testing, legionella -
✔✔What are 3 hazards caused by water?
✔✔Inerting - ✔✔Gas is forced into pipework/vessels and air is forced out as a fire
supressant
✔✔Helium, neon, argon, nitrogen, CO2 - ✔✔What are 5 types of gases used in
inerting?
✔✔Blanketing - ✔✔Term for a layer of inert gas placed over flammable liquid in a
storage tank to ensure no flammable vapour/oxygen mixes
✔✔Inerting, blanketing, fire fighting agent, pipeline freezing, back up instrument air -
✔✔5 uses for 'inert' gas
✔✔50V - ✔✔What voltage can cause heart fibrillation?
✔✔hertz - ✔✔frequency measure for cyclically varying things. like mains electricity
✔✔Amount of current; frequency; path through body; length of time - ✔✔What 4 factors
does the hazard of electricity depend on?
✔✔Frequency - ✔✔What property of electricity may cause muscle spasm?
✔✔Path through burns - ✔✔What property of electricity determines locations of burns?
QUESTIONS AND SOLUTIONS RATED A+
✔✔Safety integrity of SIS - ✔✔The average probability of a SIS performing its function
(under stated conditions for a certain period of time)
✔✔Saturated steam - ✔✔Steam that is still wet
✔✔3-5% - ✔✔What percentage of water remains in saturated steam?
✔✔Superheated steam - ✔✔Steam with temperature higher than its boiling point
✔✔Answer: Superheated steam - ✔✔Which type of steam is invisible?
✔✔Vacuum steam - ✔✔Steam created by reducing the operation pressure using a
vacuum pump, so the steam effectively below 100degs
✔✔Thermal expansion - ✔✔Hazard created by the expansion of pipelines or vessel as
a result of steam exposure
✔✔Answer: Thermal expansion - ✔✔What type of hazard is prevented by building in
flexibility or using bellows etc to allow material to expand?
✔✔Vacuum formation from steam - ✔✔Hazard created by steam producing
condensate, resulting in decreased volume
✔✔Vacuum breakers - ✔✔What measure is important to ensure there is sufficient
pressure within a system using steam to allow the condensate to be discharged?
✔✔Water Hammer - ✔✔Hazard resulting from water in a pipeline striking a fixed object
under high pressure
✔✔During start-up or under variable conditions - ✔✔At what stage of operation is water
hammer most likely?
✔✔Answer: water hammer - ✔✔What hazard is caused by water entrained in steam
being rapidly moved through a pipe (as condensate)?
✔✔Answer 2: Water Hammer - ✔✔What hazard is caused by steam rapidly condensing
due to being surrounding by cooler condensate, resulting in a massive change in
pressure due to loss of volume?
✔✔Thermal expansion, vacuum formation, water hammer - ✔✔What are three possible
hazards caused by steam?
, ✔✔Vacuum formation due to water - ✔✔Hazard caused by filling or emptying rate of
tanks/other vessels not being consistent with pressure
✔✔Vacuum breaker valve - ✔✔Measure which can be fitted to a tank so that the loss of
pressure in the head space above a liquid is compensated when the tank is being
emptied
✔✔Hydrostatic testing - ✔✔A means of checking for any leaks etc in pipelines or
vessels before start up or after alterations/maintenance
✔✔20-55 degrees - ✔✔What is the temperature range for legionella growth?
✔✔37 degrees - ✔✔What is the ideal temperature for legionella growth?
✔✔Legionella - ✔✔Hazard caused by cooling tower creating droplets of water in a
poorly maintained system
✔✔Vacuum formation, overload during improper hydrostatic testing, legionella -
✔✔What are 3 hazards caused by water?
✔✔Inerting - ✔✔Gas is forced into pipework/vessels and air is forced out as a fire
supressant
✔✔Helium, neon, argon, nitrogen, CO2 - ✔✔What are 5 types of gases used in
inerting?
✔✔Blanketing - ✔✔Term for a layer of inert gas placed over flammable liquid in a
storage tank to ensure no flammable vapour/oxygen mixes
✔✔Inerting, blanketing, fire fighting agent, pipeline freezing, back up instrument air -
✔✔5 uses for 'inert' gas
✔✔50V - ✔✔What voltage can cause heart fibrillation?
✔✔hertz - ✔✔frequency measure for cyclically varying things. like mains electricity
✔✔Amount of current; frequency; path through body; length of time - ✔✔What 4 factors
does the hazard of electricity depend on?
✔✔Frequency - ✔✔What property of electricity may cause muscle spasm?
✔✔Path through burns - ✔✔What property of electricity determines locations of burns?
