On
several occasions, we have been approached to undertake investigations
of air supply installations for both divers and sand blasters, and
thus have researched all requirements and standards.
Legal
Aspects
Minerals
Act – chapter 30.8
“No
persons shall use or permit …… All reasonable safety measures
shall also be taken to ensure the purity
of the air so supplied to a diver.”
Minerals
Act – chapter 30.20
“No
person shall use or permit or require any diver to ……… use other
than compressed natural air for
any diving operation where the diving depth exceeds 50m.
Minerals
Act – Chapter 30.21.1
“No
manager shall accept air in portable containers or apply or cause it
to be applied for use by divers unless he has been furnished with a
certificate by the supplier of the air, which guarantees the purity
of the air.”
Minerals
Act – Chapter 30.21.2
“Where
a compressor is used for the filling, ……. All reasonable measures
shall be taken by the diving supervisor to ensure that the air intake
of the compressor or pump is not contaminated with noxious fumes or
gas.”
Machinery and Occupational
Safety Act – Regulation 8
(n) “all reasonable steps are taken to ensure
that air supplied to divers is pure and that such air complies with
the requirements of the SABS Code of Practice for Portable Metal
containers for Compressed Gasses No 019-1985.”
Comments
In
terms of all the above clauses, the accent is on “purity” and
“natural”. The final
reference stipulates that no contamination is permitted.
Any trace of any “Noxious fumes or gas” constitutes an
infringement of the Act.
These
provisions override any provision stipulated in chapter 10.6.6, which
specifically applies to the underground environment, and not direct
diver consumption.
The
existence of any trace of CO in the supply indicates that
contamination has occurred.
By
implication any other gas or vapour will also constitute
contamination.
No
compressor utilising any hydrocarbon mineral or synthetic lubricating
oil should be used in any air supply applicable to diving or
sandblasting operations.
All
reciprocating type compressors are capable and do vaporise a fraction
of the oil lubricant into the air stream.
On cooling, the vapour is condensed within the pipe work,
migrating towards any oil or trapping device.
Such
devices are effective to a point and not effective at all once the
reservoirs are full or dirty. A
percentage of the oil vapour, due to its vapour pressure applicable to
the temperature of the air is never deposited or captured.
This
vapour is then ingested and hydrocarbon compounds, being carcinogenic,
expose the diver to health risks.
A
centrifugal type compressor, however, relies on lubricants only to
lubricate bearings, as the impeller does not cause friction against a
lubricated surface, only compressors of this type should ever be
considered and used as a supply generator for diving and sandblasting
air use.
When
approached, suppliers indicated that for recreation purposes, a limit
of 50 ppm (parts per million) of carbon monoxide (CO) would be
acceptable. They stress that this does not satisfy the act.
This
applies to bottled supplies and we consider these limits from a
toxicological viewpoint as being far too high.
As
a safety precaution we would advocate the installation of a portable
CO detector at the air intake and have this set to alarm at say 5 ppm
at which stage precautions could be taken for the dive to be aborted,
or the air supply to the bottle to be discarded.
Commercial
suppliers have no or few such measures in place to safeguard the
quality of supplies.
We
do not anticipate CO2 as being too much of a problem, as
the levels fluctuate continuously in normal air.
Any
exhaust (from an engine for example) would manifest as CO or NOx
and particulates termed RCD’s (Respirable Combustible Dusts).
While
both acts stipulate air purity in general terms and use the term
“all reasonable steps are taken” and “all reasonable safety
measure shall be taken” – no effort is made to quantify exactly
what is permitted and what is not permitted.
This
does not offer the diver any real measure of protection and no
measures or safeguard for the operator, as any court would require a
total definition of the “reasonable steps taken: and the
“reasonable safety measures taken”.
Recommendations
Any
air supply that could be potentially used for a diver’s supply must
be checked for any pollutant as outlined above.
Similarly
a certificate provided by a supplier should clearly indicate the
quality of air other than a general “purity” statement.
The
quality can only be gauged by certification after any pollutant checks
prove negative, or the supplier supplies an acceptable compliance
certification for the air contents.
The
operator as part of his “reasonable steps taken” should check any
batch of supplied air.
