Enclosed Space Entry — Most Asked Questions
16 questions asked about enclosed space entry across the General and Fn 3 papers, heaviest first. 1 of them are must-master.
Learn the system first
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1 Enclosed space entry?
Also asked: “Enclosed space entry. Checks?”
Answer
No one enters until the space is isolated, ventilated, atmosphere-tested and covered by a permit, with an attendant at the entrance and rescue gear ready.
- Pre-entry: blank off and isolate all connected lines, secure valves against accidental opening, ventilate thoroughly, then test the atmosphere — oxygen about 20.9%, hydrocarbon below 1% LFL, toxics within limit (CO below 25 ppm).
- Keep continuous ventilation and frequent atmosphere checks running the whole time men are inside, with adequate lighting and rescue/resuscitation gear at the entrance.
- Team leader confirms hazards, agreed communications, reporting interval and emergency/evacuation drill before anyone goes in.
- A trained attendant stays at the entrance the whole time and never enters — not even for a rescue — until the responsible officer is told and a relief attendant is posted.
Surveyor follow-up: the attendant sees a man collapse inside — what is his exact first action?
Full theory: Permits to Work: Enclosed Space Entry Criteria & Precautions -
2 State why oxygen deficiency may occur in certain spaces onboard ship. (4) (b) Describe the precautions to be taken before entry to any recently opened enclosed space
Answer
Oxygen dies by rust, rot and displacement — so ventilate, test, permit and post rescue before anyone goes in.
- Oxygen falls where rust eats it, wet cargo and residues rot, chemicals displace air, and fresh paint or fumigant seals consume it.
- Ventilate or gas-free well before entry and prove the atmosphere at several levels before the first step in.
- Work under permit with attendant, lifelines, lighting and comms, numbers limited to who the rescue team could lift.
- Keep the space ventilated while occupied, retest periodically, and leave at once if fans fail or readings sag.
Surveyor follow-up: meter reads 20.8% at the hatch but the sump was never sampled — enter or retest, and where?
Full theory: Permits to Work: Enclosed Space Entry Criteria & Precautions -
3 Enclosed space drill solas requirement
Answer
Enclosed-space rescue drills run crew through the permit before anyone needs it: team, gear and comms proved in the space.
- Muster the assigned rescue team with breathing sets, lifelines, lighting and comms at the actual entrance.
- Prove atmosphere testing, ventilation, attendant cover and casualty recovery to the muster point.
- Drill to the SOLAS timetable with every crewman rotated through — rescue unpractised is rescue unready.
- Record defects and re-drill: failed comms, flat bottles or missing tripods fail the drill, not the crew.
Surveyor follow-up: drill logged with the rescue team changed since and gear untested — valid drill or paper entry?
Full theory: Permits to Work: Enclosed Space Entry Criteria & Precautions -
4 What is enclosed space, procedure to enter, type of gas detection instrument
Answer
Enclosed means confined, dark and possibly breathless: permit, isolate, ventilate, test O₂, gas and toxics, then enter lifelined.
- A space with limited openings, poor ventilation and possible oxygen lack with flammable and toxic gases present.
- Prepare by blanking lines, securing valves, ventilating through and rigging lighting, comms and rescue gear.
- Test oxygen near 20.9%, hydrocarbons below 1% LFL, CO below 25 ppm and H₂S below 10 ppm with frequent retests.
- Enter under permit with attendant, lifelines and breathing sets — combustible-gas indicator, oxygen analyser and toxic tubes together.
Surveyor follow-up: O₂ 20.9% at the hatch with the sump untested and ventilation stopped — enter, ventilate or retest first, and where?
Full theory: Permits to Work: Enclosed Space Entry Criteria & Precautions -
5 Checks made for enclosed space entry and how is the safe oxygen content
Answer
Test before entry, not after: 20.9 per cent by volume is the air, below 19.5 is deficient and anything richer is dangerous.
- The permit is issued, the space is tested for oxygen, flammable gas and toxic gases, and the readings are recorded before anyone goes in.
- The atmosphere is acceptable at 20.9 per cent oxygen by volume; below 19.5 per cent is oxygen-deficient and unsafe to enter.
- Flammable concentration must be well below the lower explosive limit — normally the check is against a percentage of the LEL, not zero.
- And the test is continuous with a standby attendant at the entry who has the means to summon help and rescue from outside.
Surveyor follow-up: entry permitted at 18 per cent oxygen with the attendant on the bridge — which check failed first?
Full theory: Permits to Work: Enclosed Space Entry Criteria & Precautions -
6 Enclosed space entry procedure (what all things to be checked) xxque
Answer
The procedure is test, ventilate, permit, attend, and test again — with the attendant outside and nothing moved until it is all proved.
- Identify the space and check it is genuinely enclosed: isolated, emptied, cleaned and ventilated with its fans running.
- Test the atmosphere for oxygen, flammables and toxics, and re-test after any break of the ventilation or any period in the space.
- Issue the entry permit, put the attendant outside with a rescue arrangement ready, and record every entry and exit on the permit.
- Nothing in the space is disturbed before the atmosphere is proved — moving a sludge or a blank can release the whole space at once.
Surveyor follow-up: tank entered without the fan running and gas tested only at the top — where does the vapour sit?
Full theory: Permits to Work: Enclosed Space Entry Criteria & Precautions -
7 Enclosed space entry procedure and why time limit on thr permits?
Answer
Entry is isolate, ventilate, test, permit, attend — and the permit is timed because the space can change after it is signed.
- Blank or isolate connecting lines, secure the valves, ventilate through, and test oxygen, flammable and toxic gases at several levels.
- Issue the permit with the rescue team, attendant, lifelines, lighting and breathing equipment named and ready.
- Enter with continuous ventilation and periodic retesting, with the attendant holding the lifeline at the hatch.
- The time limit exists because the atmosphere can change after the test — a permit signed for an eight-hour shift is not a live test.
Surveyor follow-up: entry permit valid to end of watch with the space retested once — still valid at six hours, or re-issue?
Full theory: Permits to Work: Enclosed Space Entry Criteria & Precautions -
8 Enclosed space entry procedure, from start. What things to carry while entering enclosed space
Answer
Plan, isolate, ventilate, test, permit, then carry the gear that makes the entry survivable and the entry recoverable.
- Confirm the space is isolated, lines blanked, valves secured, and ventilation running with the fan serving the space.
- Test oxygen, flammables and toxics at the top, middle and bottom, and record the readings on the permit.
- Carry an oxygen or hose-type breathing set, a gas meter, lighting, a lifeline, a torch, a whistle and a gas-tight container if sampling is needed.
- Outside the hatch: the attendant, the rescue team with their own set, the standby pump, and a means of communication with the bridge.
Surveyor follow-up: entrant sent in with a carbon mask and no lifeline — withdraw him, or send the attendant in after him?
Full theory: Permits to Work: Enclosed Space Entry Criteria & Precautions -
9 How to ananlyze ocygen in an enclosed space
Answer
Read oxygen with an analyser, not by judgement: sample at working level, shoulder height and at the bottom, where the worst gas sits.
- An oxygen analyser draws a sample through a sensor and reads the percentage directly on the instrument.
- Take readings at several heights — the air at the top can be normal while the bottom is unbreathable.
- Record every reading on the permit, with the time, and repeat it through the job as the space is worked.
- Below about 19.5% the space is unfit, and above 20.9% an enriching atmosphere is a fire risk — both ends of the scale matter.
Surveyor follow-up: 20.9% at the hatch with the sump untested — enter, ventilate, or test at depth first?
Full theory: Permits to Work: Enclosed Space Entry Criteria & Precautions -
10 Limits of gases allowed in enclosed space
Answer
Three limits decide it: oxygen between 20.9% and about 21%, hydrocarbons under 1% of the lower flammable limit, and toxics below their limits.
- Oxygen is the first test — in a quarter volume it is normal air, and below the safe figure men lose consciousness without warning.
- Hydrocarbons must be under 1% of the lower flammable limit, leaving the space below its ignition range with margin.
- Carbon monoxide is held below 25 ppm and hydrogen sulphide below 10 ppm, with other gases against their own limits.
- A reading inside all three limits is the condition that permits entry — a single one outside it sends the entrant back out.
Surveyor follow-up: oxygen and LFL inside limits with H₂S at 30 ppm — is the space fit, and which instrument said otherwise?
Full theory: Permits to Work: Enclosed Space Entry Criteria & Precautions -
11 Safe % of oxygen to enter into enclosed space and device name to check %
Answer
Normal air is 20.9% oxygen and the space must be at or above 19.5% — read it on an oxygen analyser, not a lamp.
- A quarter volume of air is 20.9% oxygen, and the accepted safe entry figure is not less than about 19.5%.
- The instrument is an oxygen analyser, sampling the atmosphere at the level the crew will actually breathe.
- Readings above about 21% signal an oxygen-enriched atmosphere, which is a fire risk as real as a low one.
- Lamps and candles are not oxygen meters — they show flame behaviour, not the number the permit needs.
Surveyor follow-up: a flame burning brightly in the space being offered as proof of good air — is that a test, and which one decides?
Full theory: Permits to Work: Enclosed Space Entry Criteria & Precautions -
12 Solas regulation for enclosed space drill
Answer
The drill is a SOLAS requirement, not a company idea: the space is rehearsed with the real crew, the real gear and the real attendants.
- Drills are required on the ship’s safety management system and are witnessed at survey, with the muster list and the rescue team taking part.
- The drill proves the permit, the test, the attendant, the lifeline, the breathing sets and the emergency communication actually work.
- It is run on the real space, not a briefing — a rescue team that has only read the plan has not been drilled.
- A drill that exposes a defect must be recorded and closed before the next one, or the record is just a signature.
Surveyor follow-up: drill completed but the attendant was never assigned — which part of the arrangement was rehearsed?
Full theory: Permits to Work: Enclosed Space Entry Criteria & Precautions -
13 Things to carry in enclosed space
Answer
Carry the means to breathe, to be found, to be lifted out and to signal: breathing set, meter, light, lifeline and whistle.
- A hose-type or oxygen breathing apparatus — never an activated carbon mask, which gives no protection here.
- A gas meter for oxygen, flammables and toxics, and a second instrument held by the attendant outside.
- Flameproof lighting, a torch and a lifeline of adequate length with its recovery device at the hatch.
- A whistle or other means of signalling, and the vessel’s particulars in a gas-tight container if the entrant may be lost.
Surveyor follow-up: entrant equipped with a torch and a whistle but no breathing set — send him back, or accept a short look?
Full theory: LSA Chapter 3: Line Throwing, EEBD & SCABA -
14 Wat will you carry into enclosed space
Answer
Into the space: breathing set, meter, flameproof light, lifeline, torch and whistle. Outside the hatch: the attendant and the rescue team.
- Inside go the breathing apparatus, the gas meter, flameproof lighting, the lifeline, a torch and a signalling whistle.
- Outside stay the attendant holding the lifeline, the rescue team with their own set, and communication with the bridge.
- The standby bilge pump and a means of rapidly flooding or ventilating the space belong to the rescue plan, not the entrant.
- Nothing goes in that depends on the entrant’s judgement alone — the recovery side is planned before he goes.
Surveyor follow-up: attendant on the bridge instead of the hatch while the entrant is inside — who is holding the lifeline now?
Full theory: Permits to Work: Enclosed Space Entry Criteria & Precautions -
15 What all enclosed space?
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16 What will the person who is filling the enclosed space entry take with him
Answer
The entrant takes a gas detector, a lamp of the approved type, and the means to be got out — and goes in with an attendant outside.
- A portable gas detector for oxygen, flammable and toxic gases is carried by the entrant, not left on the deck.
- Lighting must be of a type permitted in the space, and the attendant outside keeps the lamps, the detector backup and the communications.
- A lifeline or a harness with a lifeline is worn so the entrant can be pulled out, which is why the attendant outside is not optional.
- And the entrant carries no loose equipment he cannot abandon quickly — a dropped spanner in a tank is a casualty recovery.
Surveyor follow-up: entrant found with a hand lamp and no detector — which of the two was the one that mattered?
Full theory: Permits to Work: Enclosed Space Entry Criteria & Precautions
Source: 123 written papers and surveyor oral banks, 24,613 entries, merged into 17,210 topics. Ticks are stored on this device only.