MASTER`S GUIDE TO: ENCLOSED SPACE ENTRY

MASTER`S GUIDE TO:
ENCLOSED SPACE ENTRY
PAGE : 37 of 60
DATE : 01.07.14
PREPARED: MAR
EDITION : 1.0
If testing reveals oxygen deficiency, or the presence of toxic gases or vapours, the space must be ventilated
and retested before entry. If in doubt, do not enter and consider seeking shore-side advice.
Testing instruments
When a Draeger tube or equivalent is used for detecting toxic gases, the sampling gas should have
sufficient time to pass through the sampling hose.
As a rule, if a manual hand rubber pump is used, approximately four squeezes are needed for each metre
of the sampling hose. If battery driven pumps are used, approximately 10 seconds for each metre of
sampling hose should be sufficient.
Refer to manufacturer’s instructions.
Atmosphere testing shall be performed:
• before every entry when the space is vacant
• after ventilation period
• at least hourly
• more frequently if conditions or suspicions warrant
Guidelines for the use of personal gas detectors
In spaces of complicated geometry with a high possibility
of pockets of atmosphere with low O2 content,
and where rescue operations may be difficult,
such as tanks and voids, the use of a portable oxygen
meter with audible alarm is strongly recommended.
A multi-gas meter, capable of simultaneous monitoring
of oxygen, combustible gases, hydrogen sulphide
and carbon monoxide, should preferably be used.
Note that carbon monoxide (CO) sensors may also
be sensitive to low concentrations of hydrogen (H2).
Therefore it is important to evaluate whether there is
CO/hydrogen in the space. Anodes may generate
hydrogen when in use.
The personal instrument should be turned on before tank entry.
If those entering are not wearing personal monitors, the person in attendance at the
entrance should conduct regular tests of the atmosphere in the space.
Calibration of monitoring equipment
Ships should be equipped only with monitors that can be calibrated. Some types of monitors come with
manufacturer-approved calibration devices – others should be sent ashore for calibration. Calibration on
board must be carried out only by a competent officer.
Monitoring equipment should always be marked with the due date of the next calibration.
The equipment should not be used if calibration of the device is overdue.
MARISCON GROUP 01.07.2014