NEBOSH HSE PSM CORE EXAM TEST 2026 QUESTIONS AND
SOLUTIONS RATED A+
✔✔PFD - ✔✔Probability of failure on demand - probability of component failure to
perform safety function at the time needed.
✔✔MTBF - ✔✔Mean time between failures - A metric that provides a measure of a
system's reliability and is' usually represented in hours. The MTBF identifies the
average time between failures. '
✔✔SIS - ✔✔Safety instrumented system - Sensor(analyser), logic solver(PLC) and final
element(valve)
✔✔SIL - ✔✔Safety integrity level - average probability of a SIS performing its function. 4
levels, 4 being highest safety integrity.
✔✔Legionella survives at what T* - ✔✔20* - 55*C
✔✔Hertz - ✔✔The standard unit of frequency.
✔✔Electrostatic charge by friction can't form between what two states? - ✔✔gas-gas
✔✔ESD - ✔✔Emergency shut-down - minimise consequences, can be ROSOV
✔✔PV - ✔✔Pressure-Vacuum (vent) - allows air in but not out.
✔✔Bund should hold how much volume of tank design? - ✔✔110%
✔✔Flammable - ✔✔Material readily catch fire if ignited by heat source
✔✔conduction - ✔✔heat transfer through solid material
✔✔convection - ✔✔heat transfer through liquid or gas
✔✔radiation - ✔✔transfer radiant heat from hot objects. Electromagnetic wave energy
✔✔BLEVE - ✔✔Boiling liquid expanding vapour cloud explosion
✔✔CVCE - ✔✔confined vapour cloud explosion
✔✔UVCE - ✔✔unconfined vapour cloud explosion
✔✔Intumescent - ✔✔material that expands when heated as a result, fills space and
prevents spread of fire and smokes
, ✔✔Inert - ✔✔Chemically inactive
✔✔On-site plan - ✔✔an internal plan detailing the site's emergency response; may
include calling external regulators
✔✔Off-site plan - ✔✔external agencies plan of response
✔✔Roll call - ✔✔process similar to reading the school register during which every
person registered on site is checked to ensure they have assembled at the muster
point.
✔✔Tabletop exercise - ✔✔A discussion-based exercise where participants talk through
an event while sitting at a table or in a conference room. It is often used to test
emergency response plans.
✔✔Zone 0 - ✔✔a place with explosive atmosphere is present continuously
✔✔Zone 1 - ✔✔a place with explosive atmosphere is likely to occur in normal operation
occasionally
✔✔Zone 2 - ✔✔a place with explosive atmosphere is not likely to occur in normal
operation, but if it does occur, will persist for a short period only.
✔✔Zone 20 - ✔✔A place in which an explosive atmosphere in the form of a cloud of
combustible dust in air is present continuously.
✔✔Zone 21 - ✔✔a place in which an explosive atmosphere in the form of a cloud of
combustible dust in air is likely to occur in normal operation occasionally.
✔✔Zone 22 - ✔✔a place in which an explosive atmosphere in the form of a cloud of
combustible dust in air is not likely to occur in normal operation, but if it does occur, will
persist for a short period only.
✔✔ - ✔✔
✔✔ Immediate cause - ✔✔The unsafe act or unsafe condition that leads directly to the
consequences (caused harm, damage, etc)
✔✔Root cause - ✔✔An underlying circumstance that allowed the unsafe condition or
act to exist (mainly organisational and management failings)
✔✔MOC - ✔✔Management of Change
SOLUTIONS RATED A+
✔✔PFD - ✔✔Probability of failure on demand - probability of component failure to
perform safety function at the time needed.
✔✔MTBF - ✔✔Mean time between failures - A metric that provides a measure of a
system's reliability and is' usually represented in hours. The MTBF identifies the
average time between failures. '
✔✔SIS - ✔✔Safety instrumented system - Sensor(analyser), logic solver(PLC) and final
element(valve)
✔✔SIL - ✔✔Safety integrity level - average probability of a SIS performing its function. 4
levels, 4 being highest safety integrity.
✔✔Legionella survives at what T* - ✔✔20* - 55*C
✔✔Hertz - ✔✔The standard unit of frequency.
✔✔Electrostatic charge by friction can't form between what two states? - ✔✔gas-gas
✔✔ESD - ✔✔Emergency shut-down - minimise consequences, can be ROSOV
✔✔PV - ✔✔Pressure-Vacuum (vent) - allows air in but not out.
✔✔Bund should hold how much volume of tank design? - ✔✔110%
✔✔Flammable - ✔✔Material readily catch fire if ignited by heat source
✔✔conduction - ✔✔heat transfer through solid material
✔✔convection - ✔✔heat transfer through liquid or gas
✔✔radiation - ✔✔transfer radiant heat from hot objects. Electromagnetic wave energy
✔✔BLEVE - ✔✔Boiling liquid expanding vapour cloud explosion
✔✔CVCE - ✔✔confined vapour cloud explosion
✔✔UVCE - ✔✔unconfined vapour cloud explosion
✔✔Intumescent - ✔✔material that expands when heated as a result, fills space and
prevents spread of fire and smokes
, ✔✔Inert - ✔✔Chemically inactive
✔✔On-site plan - ✔✔an internal plan detailing the site's emergency response; may
include calling external regulators
✔✔Off-site plan - ✔✔external agencies plan of response
✔✔Roll call - ✔✔process similar to reading the school register during which every
person registered on site is checked to ensure they have assembled at the muster
point.
✔✔Tabletop exercise - ✔✔A discussion-based exercise where participants talk through
an event while sitting at a table or in a conference room. It is often used to test
emergency response plans.
✔✔Zone 0 - ✔✔a place with explosive atmosphere is present continuously
✔✔Zone 1 - ✔✔a place with explosive atmosphere is likely to occur in normal operation
occasionally
✔✔Zone 2 - ✔✔a place with explosive atmosphere is not likely to occur in normal
operation, but if it does occur, will persist for a short period only.
✔✔Zone 20 - ✔✔A place in which an explosive atmosphere in the form of a cloud of
combustible dust in air is present continuously.
✔✔Zone 21 - ✔✔a place in which an explosive atmosphere in the form of a cloud of
combustible dust in air is likely to occur in normal operation occasionally.
✔✔Zone 22 - ✔✔a place in which an explosive atmosphere in the form of a cloud of
combustible dust in air is not likely to occur in normal operation, but if it does occur, will
persist for a short period only.
✔✔ - ✔✔
✔✔ Immediate cause - ✔✔The unsafe act or unsafe condition that leads directly to the
consequences (caused harm, damage, etc)
✔✔Root cause - ✔✔An underlying circumstance that allowed the unsafe condition or
act to exist (mainly organisational and management failings)
✔✔MOC - ✔✔Management of Change
