Health and Safety
Executive / Commission
Contract Research Reports
On certain industrial sites (such as water treatment plants),
chemicals which are gaseous at atmospheric pressure and temperature
are stored as a liquid either by refrigeration (at ambient
pressure) or pressurisation (at ambient temperature). If such a
vessel develops a small rupture, pressurised liquid escapes as a
jet into the local environment, or if a large rupture forms, the
material may 'spill' onto the ground. If the chemical is
stored at ambient temperature and at its saturation pressure, and a
jet release occurs, it will quickly vaporise upon entering the
lower pressure regime of the local environment. This may be
justified since a fraction of the pollutant flashes to the vapour
phase immediately whilst the remaining liquid constituent vaporises
within 2-3 metres [1]. For a release into an enclosed space, the
vaporised pollutant mixes with the air in the room, resulting in
the reduction of the overall temperature of the room contents,
accompanied by a further drop in pressure. This has the effect of
producing a small vacuum, which draws in fresh air from outside the
building through any available openings.
Some of these research reports are very large. For information about expected download times please see our FAQs pages.