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AN INTRODUCTION TO LPG INSTALLATIONS

Any fuel that produces a flame consumes oxygen when burning and gives off carbon dioxide (CO2) and water vapour. Boats interiors have little volume, and cabin spaces are normally well sealed (they must be to be watertight). The oxygen available in a closed cabin can be consumed quite rapidly. Insufficient oxygen makes the fuel burn improperly and, instead of producing carbon dioxide, it begins to form a deadly carbon monoxide (CO). The combination of oxygen loss and carbon monoxide build up can be fatal-it has caused a number of deaths over the years. Always insure adequate ventilation when burning any fuels; this includes running diesel engines, which sometimes obtain their air via the living spaces in spite of the fact that they should be independently vented. Do not use an appliance for heating unless it is so designed. Never leave a heater on overnight unless it is vented outside the cabin area and adequate air supplies are assured.

LPG (Liquid Petroleum Gas) is kept under pressure as a liquid and when released becomes a heavy flammable gas that is much heavier than air. The aim therefore is to minimise the risk of this gas escaping into your boats interior, where it could quickly accumulate, creating an explosive ‘mix’ of gas and air.

This chapter concentrates on how best to store LPG, how to supply your gas appliances and how to protect the gas system and installation from heat and impact damage. It is always strongly recommend that any work on LPG systems is carried out by a competent gas fitter.

GAS

The two main types of gas in wide spread use are propane and butane.

Butane and propane both liquefy at low pressures and temperatures. As gas is pumped into a cylinder at ambient temperatures, these pressures are reached quickly. Then as more gas is pumped in, it liquefies-with temperatures and pressure remaining relatively stable. When a full cylinder is rocked from side to side, the liquid can be heard sloshing around inside. In higher ambient temperatures, pressures in an LPG cylinder will increase somewhat, but never beyond 250PSI; in lower temperatures, it will decrease.

As long as an LPG cylinder is kept upright, there will always be gas at the top, liquid at the bottom, and stable pressure-until the cylinder is almost empty. At this point the pressure begins to fall as the last of the liquid evaporates.

The principle difference between butane and propane is the former liquefies at higher temperatures and lower pressures for the latter. In extremely cold weather, liquid butanes rate of evaporation from a cylinder can slow to the point at which appliances fail to work properly. In these conditions propane should be substituted.

In the UK appliances operating on Butane do so at a pressure of 28 millibars and Propane at 37 millibars. It is not generally possible to change from one fuel to the other without changing the regulator, hence the cylinders and regulators have different threads and fittings to avoid mishaps. As a point of interest butane has a higher calorific value and a slighter hotter flame temperature.

SAFETY PRECAUTIONS

LPG forms a dangerously explosive mixture when combined with oxygen in the air. LPG is considerably heavier than air-gas leaks sink to the bilges. LPG leaks are particularly dangerous on boats: Small leaks can remain undetected in deep bilges. A tiny spark (which can be generated by static electricity on any boat) can blow the boat apart.

INSTALLATION PRACTICES

Compartment requirements: Gas bottles, both in use and in storage, must be kept well secured in compartments that are sealed from all machinery and living spaces, and vented overboard. LPG compartments need to be vented from the base with a minimum internal diameter of 19mm (B.S.S exemption to 12mm on older vessels), which slopes continuously downwards so that no water can form a U-trap, which exit’s the hull above the waterline at all angles of heel. This is continuously picked up during surveys, many drain hoses are found to be looped up and contain water! All gas vents must exit well clear of engine exhausts, ventilators, and air intakes. Gas cylinders must be secured in an upright position (again very few cylinders during surveys are secured properly). If an LPG cylinder tips over, liquid instead of gas might come out-with potentially dangerous results.

MARINE GAS DETECTION

Suitable means for detecting the leakage of gas should preferably be provided in each compartment containing a gas-consuming appliance. Gas sensor heads should be protected against damage caused by water and other corrosive agents, and the risk of mechanical damage.

The consequences of an LP gas leak on board a boat can be disastrous. Every year there are deaths and injuries on board boats, which could have been avoided with the installation of easy to use and cost effective gas detection equipment.

LP Gas is not regarded as poisonous but is explosive and can lead to devastating explosions if it builds up to sufficient levels. It is measured using what's called the Lower Explosive Limit (LEL). This means that when the concentration of gas reaches 100% LEL it becomes explosively dangerous (i.e. if you lit a match it would go bang). Most gas alarms are calibrated to alarm at 10% LEL, well before the gas becomes explosively dangerous.

A strong smell of gas can be noticed when the concentration is only 0.5% to 1% LEL because gas suppliers add a harmless but strong smelling chemical to the gas. Despite the strong smell this level is not dangerous and therefore the alarm will not sound. This reduces the possibility of false alarms.

        BSS Examination Checking Procedures from April 05– Part 7

                                        LPG Instalations

The BSS recommend highly preparing your boat (if kept on inland waterways) to the current BSS requirements, indeed meeting all the points in the list of checks below will give you confidence that your boat meets the requirements and is safer for you and your crew too. Reinforcing this, the new edition of the BSS Essential Guide will urge people to meet all industry excepted standards, to install equipment following suppliers guidelines, to use only equipment designed for the rigours of the marine environment and carry out routine checks and maintenance. We as Marine Surveyors also highly recommend that all boat owners should look to meeting all the requirements listed below.

Note: The following standards have been taken from the original BSS Technical Manual with adjustments made to include changes made since the introduction of the revised BSS Checking Procedures 2-April 20005. 

There are seven relevant BSS general requirements:

1. All LPG systems must be designed, installed and maintained in a way that minimises the risks of explosion or of fire starting and spreading.
2. All LPG containers and high pressure components must be secured in a postion where escaping gas does not enter the interior of the vessel.
3. All LPG systems must be designed, installed and maintained to ensure gas tight integrity.
4. All LPG system connections and flexible hoses must be accessible for inspection.
5. All LPG control and shut off devices, or means to operate thaem must be ready accessible.
6. LPG shut off valves, or thier means of operation, must be marked when not in clear view or when their function is not clear.
7. All LPG systems must have a suitable means to test that the system is gas-tight.

LPG INSTALLATIONS - STANDARDS

Storage of LPG Cylinders

Every cylinder (full or empty, stored or in use) shall be either:Secured on open deck, cabin tops or outside cockpits so that any leakage flows overboard. Cylinders, low pressure regulators and associated equipment shall be at least 1 m away from hatches, other openings and possible sources of ignition. (NOTE: Cylinders, low pressure regulators and associated equipment may be enclosed in a shelter on open deck, cabin tops or outside of cockpits provided the shelter conforms to this sub-paragraph.) or

Secured in a cylinder locker LPG-tight to the hull interior at least to the level of the cylinders, low pressure regulators and associated equipment. Cylinder lockers shall only be openable from the top and shall be provided with a lid or cover to protect cylinders, low pressure regulators and associated equipment from mechanical damage. Cylinder lockers shall be ventilated from outside the vessel to a point above the level of the cylinders.

A means to drain LPG away from the vessel shall be provided from the lowest point of the cylinder locker to a point outside the hull above the deepest loaded waterline. (NOTE: Cylinders may be secured in a cylinder housing in a self-draining cockpit provided the installation is in accordance with the appropriate Standard).

Cylinders and associated equipment may be secured in a shelter on open decks, cabin tops or outside cockpits providing the shelter conforms to the standards to follow in this section 7.21.

The use of cylinder lockers or housings, constructed to these standards are preferable to the use of shelters. Cylinder locker housings provide the best possible protection for cylinders and associated equipment and reduce the risks in the event of a gas leak at the cylinder location.

For existing boats, cylinders may be stored on brackets or shelves fixed to the outside face of the transom but this is not recommended practice. In these circumstances the cylinders, regulators and associated pipework must be protected from mechanical damage in the event of collision and be ventilated to allow escaping gas to flow directly overboard.

Every cylinder (stored, in use full or empty) shall be secured on open deck, cabin tops or outside cockpits so that any leakage flows overboard.

There should be no obstructions in the downward path to the flow of gas which could form a ‘dam’ behind which gas could accumulate.

LPG is heavier than air and always seeks a downward path when free to do so. It is this property which allows any escaping gas from properly sighted cylinders, cylinder lockers and housings to flow overboard and away from the vessel.

If it is not dispersed overboard it may accumulate in the bilge or bottom of the boat from where it cannot be easily removed.

Care needs to be taken in locating cylinders, cylinder lockers and housings to ensure an unobstructed path for leaking gas that the position chosen does not form an obstruction to persons moving about the vessel.

Example image (BSS fail).

This gas cylinder was located in a side opening locker.( upper deck on a Trawler Yacht). The principle design was acceptable as any leaking gas would drain over the deck and overboard, however on close inspection gaps were noticeable around the cables and conductors coming up from the engine room, therefore any leaking gas could possibly find its way down below decks and into the bilges. 

Cylinders, low pressure regulators and associated equipment shall be at least 1m away from hatches, other openings and possible sources of ignition.

Cylinders must be sited away from all hatches and openings so that any escaping gas cannot find its way into the interior of the vessel.

The minimum distance must be 1m away from any hatch or opening but whatever the distance, there should be no openings of any kind in the path of the leaking gas which would allow it to find its way back into the interior of the boat.

In this context, the terms ‘openings’ includes both permanent openings and those capable of being closed without the use of tools, whether they are open or not at the time of the examination.

Cylinders, low pressure regulators and associated equipment shall be at least 1m away from possible sources of ignition.

Cylinders, must be sited so there is no danger of any escaping gas being ignited.

Possible sources of ignition include the pilot lights of appliances or spark induced electrical equipment such as appliance automatic ignition systems or non-flame proof solenoid shut-off valves.

In addition to being 1m away, there should be no such ignition source in the path of leaking gas irrespective of the distance it is located from the cylinder installation.

Cylinders not stored on open decks, cabin tops or outside cockpits must be secured in a cylinder locker.

There is one variation to this rule which can be applied to the stowage of cylinders in self draining cockpits. The best practice is to comply with these standards and secure the cylinder in a cylinder locker but in this case only, it would be permissible to install a cylinder housing providing the housing complies with standard 7.2.4 that is the cockpit is LPG tight to the vessels interior. (commented on later).

Cylinders not stored on open decks, cabin tops or outside cockpits must be secured in a cylinder locker LPG tight to the hull interior at least to the level of the cylinders, low pressure regulators and associated equipment.

If the regulator or associated equipment is lower than the cylinders, the cylinder locker must be LPG tight at least to the height of the cylinder valve.

This means that if any part of the installation within the locker develops a leak for any reason the leak will be contained in the locker and will drain overboard through the drain at the bottom.

Apart from the requirement for cylinder lockers to be located above the waterline there are no limits set for the overall depth of the locker. Providing it is LPG tight to the height prescribed, any part of the locker above that height, which includes the lid or cover, need not be LPG tight.

LPG is extremely searching as described in the introduction and the smallest defect will breach the LPG tight integrity of the locker.

Providing the cylinder locker is constructed in accordance with these standards, no test for LPG tightness is being made at present. However a careful visual examination will be made of the structure both inside and to ensure the are no signs of damage or deterioration which would allow leaking gas to the hull interior.

Visually check the cylinder locker is LPG tight to the hull interior to the level of the cylinders, regulators and associated equipment by examination of the bottom, sides, and seams for signs of:

This steel gas locker was showing signs of significant corrosion around the base and lower seams. It was recommended that the locker was removed and restored to its original condition.

Cylinder lockers shall only be openable from the top.

LPG is heavier than air and extremely searching and reliance cannot be placed on the effectiveness of any side door seal. Even if an effective seal could be developed, reliance could not be placed upon the practice of the user to close side openings.

Cylinder lockers shall be provided with a lid or cover to protect below pressure regulators and associated equipment from mechanical damage.

Lids or covers must be made robust enough to withstand any use to which they might be put, particularly if they are used as a seat or step.

There is no requirement to make the lid or cover LPG tight as the locker is required to be ventilated above the level of the cylinders.

Lids or covers must be made relatively weatherproof to reduce the risk of water and debris finding their way into the locker. These could damage the regulator and associated equipment and block the locker drain.

Cylinder lockers shall be ventilated from outside the vessel to a point above the level of the cylinders.

The provision of high level ventilation concerns the creation of latent heat to aid vapourisation. As LPG becomes a vapour the contents of the cylinder are cooled thus reducing the vapourisation rate. High level ventilation introduces warmer air around the cylinder which helps maintain the vaporisation rate.

The provision of high level ventilation also helps create an air flow through the locker or housing which should help remove LPG through the drain in the event of a leak.(see image below, the top vent can be seen top right).

The total cross-section area at high level ventilation openings should be at least equal to that of the locker drain.

Where high level ventilation is introduced above the cylinder but below the low pressure regulator and other associated equipment, any hose used should be suitable for use with LPG. Suitable hoses include EPDM hoses (ethylene propylene diene monomer) and hoses suitable for petroleum products.

The maximum length of ventilation hoses should not exceed 5 times the internal diameter of the duct.

Where the cylinder locker or housing is an internal part of the hull it may be ventilated by means of a direct opening through the hull.

EXEMPTION: Apart from hire cruisers licensed with the Broads Authority, vessels manufactured prior to 3 January 2000 are not required to comply with the part of this Standard which requires cylinder lockers to be ventilated from outside the vessel to a point above the level of the cylinder.

Installation of Cylinders All cylinders shall be installed in an upright position with the valve uppermost and secured so that no damage can occur to the cylinders, regulators, hoses or pipework. Cylinders, cylinder lockers or cylinder housings shall not form an obstruction for persons moving about the deck or walkway or interfere with the normal operation of the vessel. Cylinders, cylinder lockers or cylinder housings shall not be located near to heat sources. All cylinders shall be accessible and removable in an emergency.

Installation in upright position

All cylinders shall be installed in an upright position with the valve uppermost and secured so that no damage can occur to the cylinders, regulators, hoses or pipework.

Cylinders should remain upright and installed with the valve uppermost so there is no danger of liquid LPG entering the regulator or pipework.

If liquid does pass into the regulator, high pressure maybe created in the low pressure stage of the regulator which could result in diaphragm failure with the subsequent risk of high pressure LPG entering the low pressure system.

Cylinders to be secured

All cylinders full or empty, whether free standing or stowed in cylinder lockers, housings or shelters, must be secured to prevent damage to the cylinders, regulators, hoses or pipework.

Cylinders must be restrained individually or collectively to a fixing of sufficient strength to ensure that they cannot move in the event of:

Over 19Kg - no movement, secured near bottom.

3Kg-19Kg - sideways movement to be less than 50mm.

Below 3 Kg - Must not be able to fall over.

Example image BSS fail

This 7Kg gas cylinder in the picture above was being partially supported by an old fender!

Suitable fixing devices include:

Cylinders, cylinder lockers or housings shall not form an obstruction for persons moving about deck or walkway or interfere with the normal operation of the vessel.

The normal operation of the vessel would include such things as interference with mooring lines or their securing points.

It is important that this requirement is taken into account when providing for an unobstructed pathway for leaking gas to drain overboard.

Cylinders, cylinder lockers or cylinder housings shall not be located near to heat sources.

Cylinders are designed to operate within normal ambient temperature, including direct sunlight, and must not be exposed to any heat source which is likely to raise the temperature above this.

As gas pressure is directly related to temperature, the pressure in the cylinder in normal conditions is well within the design standards of the cylinder and its valve.

If the temperature rises above the design standard, the over pressure in the cylinder will open the built in pressure relief valve and gas will vent to reduce the pressure inside.

Disposable cartridges are not fitted with pressure relief valves and exposure to excessive heat must be avoided.

Cylinder lockers or housings must protect cylinders secured or stored in them from any such increase in temperature so they must be located away from any heat source which could raise the interior temperature.

All cylinders shall be accessible and removable in an emergency.

The purpose of this requirement is to ensure access for both the occupants of the vessel and the emergency services in the event of an accident.

For security purposes when the boat is not in use, it would be acceptable for a lock to be used as part of the securing mechanism for free standing cylinders. When the boat is in use, the means of releasing any cylinders securing devices should be in a ready accessible location known to all occupants of the vessel.

Equally, it would be acceptable to secure a cylinder locker, housing or shelter, providing the main shut off valve remains accessible when the boat is occupied, and the position is clearly marked (discussed in detail later).

Construction of lockers and housings Cylinder lockers or cylinder housings shall be constructed of metal of thickness at least 0.9 mm, with welded or brazed joints, or of fibre reinforced plastics (FRP) of minimum thickness 5 mm, or of materials having a fire resistance of 30 min in accordance with BS 476-20.

Materials used in the construction of cylinder lockers

The cylinder locker or housing needs to provide protection for the cylinder installation in the event of fire or impact damage.

It must be thick enough and of a fire resistant quality to provide a barrier to fire for at least 30 minutes to provide an opportunity for the fire to be tackled.

Whatever metal is used to make the cylinder locker or housing, it must be at least 0.9mm thick to provide the necessary protection. If it is less than this, the owner will need to provide documentary evidence that it meets the requirements of BS 476-20 and it will be treated as a non-metal locker housing.

Fibre reinforced plastic must be:

An adequate thickness would be at least 5mm.

If it is less than this, the owner will need to provide documentary evidence that it meets the requirements or it will be treated as a non- FRP locker.

Alternative materials to metal thickness 0.9mm or FRP thickness 5mm are acceptable provided they are thick enough and are of a fire resistant quality to provide a barrier to fire for at least 30 minutes.

Fire resistant resins are available and the specification sheet of the resin used may provide satisfactory documentary evidence in cases where the thickness of FRP is less than 5mm.

The material must be string enough to minimise the risk of impact damage.

Example image

This owner really though about the design of his gas locker. Not only did he mould up a good quality fibreglass bin, he also surrounded it with fire retardant expanding foam (pink) and then fitted a steel lid, the whole thing was then enclosed in marine grade plywood and turned into the navigators seat in the cockpit. (excellent job done).

The joints and seams must be made in such a way that they:

Joints made with rivets, bolts or screws, or low melting point fillers are not acceptable.

If the cylinder locker or housing has been constructed as an integral part of the hull, some of the joints and seams may not be fully welded or brazed e.g. they could be riveted construction. This is acceptable providing any gas leaking through such a joint or seam could not find its way into the hull interior.

Cylinder locker / housing drains Cylinder locker or cylinder housing drain pipes, hoses and connections shall be of a material suitable for use with LPG. Drains shall have an internal diameter of at least 19 mm (3/4”).

Drain pipes/hoses

Cylinder locker or housing drain pipes, hoses and connections shall be of a material suitable for use with LPG.

This standard has been changed from April 2005 and now a drain hose found in a good condition with all connections complete is acceptable, however one new additional standard has been added and that is: The hose must continiously fall to outside the hull to prevent any leaked LPG from being retained.

There should be no joints in the drain pipe or hose other than those connecting it to the cylinder locker or housing and the through hull fitting.

As drains are not permanently charged with gas, metal drain pipes need not comply with the standard which states that pipework is to be made of seamless copper, stainless steel, or copper nickel alloy.

Natural rubber and many plastics can be attacked by LPG and such materials are not recommended as suitable for use as drain hose, however these are not classed as failures from April 2005.

Visually check drain pipes, hoses and connections for:

Corrosion

Damage

Deterioration

Missing components

Freedom from burrs and rough edges

Over-tightened hose clamps

Hose clamps fixed by spring tension only

Over sized clamps causing pinch points

Under sized clamps causing the clamp rack not to be fully engaged.

Determine by measurement all clips and clamps are at least 8mm in width.

A very noticeable corroded drain hose clamp. Time to change this one!

Drains shall have an internal diameter of at least 19mm (¾ inch).

This requirement is applicable to the whole length of the drain pipe or hose.

The dimension is a minimum figure. For systems with cylinder sizes or combinations of cylinders that exceed 38Kg total capacity it is recommended that the drain diameter be enlarged. (see table below).

EXEMPTION: Vessels manufactured prior to 3 January 2000 and having an LPG drain with a minimum internal diameter of 12mm for a cylinder up to 15Kg capacity and which is enlarged proportionally for additional storage, are not required to comply.

For some standard cylinder sizes and combinations this would be recommended in the following table. Note that for a total capacity of more than 47 Kg the table represents guidance only.

TOTAL CAPACITY	VENT PIPE/OPENING I.D
15Kg or less	12mm
19Kg	14mm
30Kg	17mm
38Kg	19mm
47Kg	20mm
94Kg	30mm

Openings into lockers and housings The opening into a cylinder locker or cylinder housing shall enable the operation of valves, replacement of cylinders, and access to connections or regulating devices. The opening into a cylinder locker shall not be situated in an accomodation space, engine space, fuel space or battery space.

Opening into cylinder lockers or housings

The opening into a cylinder locker or housing shall enable the operation of valves, replacement of cylinders and access to conncetions or regulating devices.

The opening should allow the functions to be performed with a full complement of cylinders in the cylinder locker. This fault could be regarded as a design/construction requirement, however the following checks should be carried out.

CHECKING

Visually and manually check all valves can be reached through cylinder locker or housing openings.

Visually and manually check all connections and regulating devices can be reached.

Location of opening into cylinder lockers or housings

The opening into a cylinder locker shall not be situated in an accomodation space, engine space or battery space.

Separation from accomodation spaces.

Cylider lockers should be separate from accomodation spaces to:

• reduce the risk to the occupants of the vessel, especially in the event of a catastrophic high pressure gas leak.
• provide the fire and rescue services with awareness of the likely position of, and better access to the cyliders in the event of a fire on the vessel.

Engine fuel and battery spaces.

Engine, fuel and battery spaces would be at risk from excessive heat caused by:

• engine running.
• the fire hazard created by the presence of fuel vapours.
• spark producing equipment.
• engine exhaust system.

NOTE: The April 2005 changes to the BSS now permit the cylinder locker to be in an accomodation space provided it is in a low risk area and not exposed to heat, sources of ignition, or potential impact damge.

CHECKING

Visually check cylinder locker is in a low risk position outside engine, fuel or battery spaces.

Housings in self draining cockpits Cylinder housings may open from the side into self draining cockpits provided that: The drain outlets from the self draining cockpit are above the deepest loaded waterline and the design of the craft ensures the self draining cockpit is LPG tight to the interior of the vessel at least to the height of the LPG cyliders, low pressure regulators and associated equipment. Any hatches or openings within a none self draining cockpit are watertight and the cylinder locker housing seals must be free from signs of gaps and damage and must satisfy and pass the smoke pellet test.

Use of cylinder housings in self draining cockpits.

A cylinder housing is a storage space for LPG cylinders, low pressure regulators and associated equipment, openable from the side or top and side.

It is recommended that cylinders in self draining cockpits be secured in a cylinder locker, however, cylinders located in self draining cockpits may be secured in a cylinder housing provided the cockpit itself meets the relavent construction requirements.

Cylinders in any other cockpit may only be secured in a cylinder locker unless the cylinder housing will pass a smoke pellet test. Note: This test has been newly introduced into the BSS scheme from April 2005 and at this time adequate training to perform the smoke test has not been provided to all instructors.

Example image, BBS fail.

The effectiveness of this side opening cylinder locker door, quite clearly seen, can not be verified.(especially with the louvre door ventilator noticeable in the fore- picture!!) Door seals must be free of signs of gaps in the contact with the locker body, and must be free of damage and deterioration. Under the new rules for side opening lockers (introduced in April 2005) this installation will need to satisfy the smoke pellet test to pass.

LPG tightness

If the effectiveness of side opening cylinder locker door seals cannot be rectifed, or if cylinders are stored in cylinder housings, then the arrangement of a self draining cockpit must be followed:

• the height of cockpit drain outlets must be above normal laden waterline;and,
• the cockpit must be LPG tight to the interior of the vessel to the height of the LPG cylinder valves and other high pressure stage components where these are locted higher;and
• hatches or openings, and associated seals, gaskets, below the height of the LPG cylinder valves and other high pressure components where these are located higher must be free of signs of damge and deterioration.

Risk of damage in lockers and housings Cylinder lockers or cylinder housings shall not contain any items that could damage the low pressure regulator or associated pipework, or obstruct the drain or ignite leaked LPG.

Storage in cylinder lockers & housings

Cylinder lockers and housings must not be used for general storage. Solid objects such as mooring pins, hammers and other tools can easily damge parts of the cylinder installation, particularly if removed or replaced without care.

It is not necessary for there to be any signs of damge to any part of the installation-the risk alone is sufficient to create a fault here.

CHECKING

Visually check the cylinder locker or housing for any item that could damage the regulator or pipework or equipment.

Risk of blocked drain

Cylinder lockers or housings shall not contain items that can obstruct the drain.

Cylinder lockers or housings should not be used for storing any materials or equipment which could possibly obstruct the drain. Soft materials such as buoyancy aids, ropes and or cleaning gear are particularly likely to cause a drain blockage.

CHECKING

Visually check the cylinder locker or housing for any item that could obstruct the drain.

Example image

As can be seen in the image above, various items, including old bits of carpet have been stowed in the gas locker and could obstruct the drain outlet (visible below the regulator). The cylinder should be secured properly and there is also the locker corrosion to monitor.

Ignition of leaking gas

Cylinder lockers or housings shall not contain any items that could ignite leaked LPG.

The cylinder locker or housing is to be checked for obvious spark-inducing electrical equipment or any other obvious source of ignition.

Unless there is obvious evidence to the contrary, solenoid controlled gas shut off valves may be installed in a cylider locker or housing for the present, whether or not the valves are associated with electronic gas detection equipment.

CHECKING

Visually check the cylinder locker or housing for any item that could ignite leaking gas.

Is the drain opening at or close to the bottom of the cylinder locker or is any volume beneath the drain opening minimised by the use of suitable material

Since April 2005 a new standard has been introduced which recommends that cylinder locker drain openings must be located at the bottom of the locker or at the lowest point of the side.

Any area in the cylinder locker 25mm below the drain that could retain leaked LPG must be filled with LPG-resistant material. Applicability-openings located immediatley above the depth of any welds are acceptable.

A readily accessible main shut-off valve shall be fitted and installed as close to the LPG cylinder(s) as practicable The valve of any LPG cylinder or of a connected low pressure regulator may be used as the main shut off except where two or more LPG cylinders are connected by an automatic changeover device. Where an automatic changeover device is fitted the main shut off valve shall be situated as close to the outlet device as practicable. If the main shut off valve is not in a clearly visible position or is in a space that can be closed off by doors or lids, then its position should be clealy marked. If there is more than one shut off valve, this and the locations of the other main shut off valves shall be clearly marked on or adjacent to each valve.

Provision of main shut-off valve

Each seperate gas system must be fitted with a main shut-off valve installed as close to the cylinders as practicable.

There is no requirement to fit a main shut-off valve where the valve of any LPG cylinder or of a connected low pressure regulator is used as the main shut -off.

Accessibility

The main shut- off valve must be ready accessible but it may be contained in a lockable cylinder locker or housing providing always that when the boat is occupied the locker remains unlocked.

When the boat is not occupied, the cylinder locker or housing may be locked providing the position of the valves is clearly marked and at the time of the Boat Safety Scheme examination the cylinder locker or housing is unlocked.

Proximity to cylinders

A readily accessible main shut off valve shall be installed as close to the LPG cylinders as practicable.

It is important that the main shut off valve is as close to the cylinders as possible in order to reduce the length of pipework containing gas when the shut off is closed.

Ideally the main shut off valve should be in the cylinder locker if there is one, or immediatley outside.

CHECKING

Visually check the main shut-off valve is located as close to the cylinders as practicable, but note that accessibility has priority over proximity.

Use of cylinder or regulator valve as shut-off valve

The valve of any LPG cylinder or of a connceted low pressure regulator may be used as the main shut off except where two or more LPG cylinders are connected by an automatic changeover device.

Automatic changeover devices

The cylinder valve cannot be used as the main shut off valve if two or more cylinders are connected to an automatic changeover device. In this case, a seperate shut-off valve is required in the low pressure side(downstream of the device). Many automatic changeover devices already incorparate such a valve.

Proximity of shut off valve to automatic change over device

It is important that the main shut-off valve is as close to the automatic change over device as possible in order to reduce the length of pipework containing gas when the shut -off valve is closed.

Marking of main shut-off valve

If the main shut off valve is not in a clearly visible position or is in a space that can be closed off by doors or lids, then its position should be clearly marked.

Visibility

It is also desirable that the main shut-off valves should be easily visible so that no time is lost in turning off the gas supply in the case of an emergency.

When the boat is not in use, they may be contained in a locked cylinder locker or housing providing the position of the valves is clearly marked.

It is recommended that the marking should

• have lettering, minimum 10mm high.
• be clearly distinguishable e.g. red letters on a white background.
• not become illegible through cleaning, fading, or normal usage.

It is not necessary for the position to be marked if the valve(s) is clearly visible, visually check position is clearly marked.

High pressure stage components All high pressure stage components shall be installed on the open deck or cabin tops or outside cockpits, or in a cylinder locker or cylinder housing if there is one. If two or more cylinders are connected, each high pressure stage connection shall be protected by a non return valve. High pressure stage components not directly attached to the cylinder valve shall be connected by a pre-assembled length of flexible hose conforming to type 2 of BS 3212, fitted with integral threaded metalic ends. The hose shall be of the minimum practicable length to allow for the replacement of cylinders and shall not exceed 1m. High pressure stage components not directly attached to the cylinder valve shall be secured in a position that provides protection from mechanical damage and protects vent holes from the ingress of debris or water. External manual-adjustment type regulators shall not be fitted.

Location of components

All high pressure stage components shall be installed on the open deck or cabin tops or outside cockpits, or in a cylinder locker or cyinder locker housing.

When cylinders are installed in a cylinder locker or housing as specified, the regulator and other high pressure stage components are to be totally contained within the cylinder locker or housing. This is to ensure any escaping gas is retained within the cylinder locker or housing and dispersed overboard through the drain facility provided.

Non-return valves

If two or more cylinders are connected, each high pressure stage connection shall be protected by a non-return valve(NRV). The purpose of a non-return valve is to prevent a leak when either cylinder is disconnected.

NRVs are already incorporated in most manual and automatic changeover devices. Changeover devices manufactured in accordance with BS3016 will incorparate NRVs.

Double wall blocks may also be supplied with NRVs. This may indicated by the letters 'NRV' stamped on the hexagonal nut at the inlet connection of the wall block.

High pressure pigtails can also be supplied with NRVs and this may be indicated by marking as above.

If there is no change over device or other component which incorparates an NRV, examiners will need to identify the presence of a separate valve in each high pressure connection.

If there is no external indications of their presence in a component documentary evidence may be accepeted.

Connection of high pressure components

High pressure stage components not directly attached to the cylinder valve shall be connected by a pre-assembled length of flexible hose conforming to type 2 BS3212, fitted with integral threaded metallic ends.

Safety

If the connection were not flexible it would be extremely difficult to change the cylinders without creating stresses and strains in the rigid connection which could lead to failure and leaks.

CHECKING

Identifiy high pressure stage components not directly attached to cylinders and visually check flexible connection:

• is a pre-assembled length of hose
• complies with type 2 BS3212
• is fitted with integral threaded metallic ends

Visually check hose for sign of:

• leaks
• fllaws
• brittleness
• cracking
• abrasion
• kinking
• joins

Protection of seperatley mounted high pressure stage components

High pressure stage components not directly attached to the cylinder valve shall be secured in a position that provides protection from mechanical damage and protectes vent holes from the ingress of debris and water.

Fixing of components

Components in cylinder lockers or housings should be fixed with screws or bolts to the sides or, if secured on open deck, to part of the permanent structure of the boat.

Components on open decks, cabin tops or outside cockpits

As there may be no covered shelter to protect them, careful attention needs to be paid to the siting and protection of components on open deck.

There is a risk of damage from:

• during replacement of cylinders
• contact with heavy duty objects
• persons using them as handholds or footholds

Careful siting of the regulator will reduce the risk of damage but where some exposure cannot be avoided it may be necessary to fit a shield or cover.

This should provide the same degree of strenght as the cylinder lcoker but careful attention must be paid to the need to provide ready access to valves and joints.

Ingress of water or debris

Regulators with vent holes must alsways be mounted so that the vent hole points downwards or sideways in order to prevent the ingress of debris or water.

Regulators mounted so that the vent hole points upwards will be deemed to be not suitabily protected even if they are contained within a cylinder locker, housing or shelter.

Example image

The image above shows a properly mounted regulator with the vent hole pointing downwards.

Manually adjusted regulators

External manual-adjustment type regulators shall not be fitted.

There is one exception for some LPG fuelled stem-powered engine installations which may be fitted with a manually adjusted regulator as the delivery pressure needs to be adjusted during 'commissioning. This is acceptable.

Applicability

Regulators able to be adjusted upon removal of a 'tools to remove' dust cap as in the image above are acceptable.

Inlet gas connection The inlet gas connection on installation pipework shall be securely fixed and ready accessible. For cylinders stowed below decks or in cockpits, the inlet gas connection shall be situated inside the cylinder locker or housing. Installation pipework from the cylinder locker or housing shall either be from a bulkhead fitting or above the level of the cylinder, low pressure regulator and associated equipment.

Inlet gas connection

The inlet gas connection is the point at which the connection from the low pressure regulator is connected to the installation pipework. The inlet gas connection must be securely fixed and ready accessible.

The point where the connection is made must be protected against mechanical damage including unecessary flexing, bending and abrasion.

Where the inlet gas connection is located on open decks, cabin tops or outside cockpits there is no requirement at present for this connection to be made from a bulkhead fitting but this would be good practice and the simplest way to comply with this stanadard.

Example image

The image above shows a properly fitted inlet gas bulkhead connection. However, the feed pipe exiting the locker on the left will require further securing, plus the locker should not be used to hold unrelated items such as cleaning equipment, etc which could block the drain.

Instalation pipework Installation pipework shall be made of either: seamless copper tube conforming to BS EN 1057 with copper or copper alloy compression fittings. stainless steel tube of a grade suitable for use with LPG and a marine enviroment appropriate compression or screw fitting. copper nickel alloy, of a grade suitable for use with LPG and a marine enviroment appropriate compression or screw fitting. Note 1: Flexible hose may be used as the appliance connector to a gimbled cooking appliance, or to an appliance that requires movement for hygienic purposes. Note 2: If only a cooking appliance is installed, flexible hose may be used to connect it to the low pressure regulator, provided the length does not exceed 1m.

Unsuitable materials

The following materials are not permitted for installation pipework for the reasons given:

• aluminium (corrosion, low melting point, vibration).
• lead (creep).
• brass tubing (season cracking).
• steel tubing (corrosion).
• plastic (low melting point, low temperature embrittlement).

Use of flexible hose appliance connectors

Appliances must generally be installed with rigid metal pipes and fittings but flexible hose should be used as the appliance connector for gimballed cooking appliances, and a flexible connector is allowed for appliances required to be moved for hygienic purposes to allow for cleaning the space enclosing them.

A flexible hose used for this purpose must comply to type 2 of BS 3212. Two points should be noted before the check is applied:

• portable appliances must be connected by flexible hoses.
• a flexible hose not exceeding 1m may be used to connect to a cooking appliance to the low pressure regulator providing it is the only appliance in the system.

Flexible hoses Flexible hose shall conform to type 2 of BS 3212. Flexible hose shall be of minimum practicable length, not exceeding 1m, and shall be ready accessible. Flexible hose shall be installed without stress or tight radius turns and hose passing through bulkheads, partitions, deckheads, or decks shall be protected from abrasion. For low pressure appliances, flexible hose shall be a pre-assembled length fitted with integral threaded metallic ends, or secured to nozzles by a metal crimped clip or worm drive hose clamp. Hose clamps fixed by spring tension shall not be used. Hose clips and clamps shall be of the correct size for the hose and atleast 8mm in width. Flexible hose shall not be used where it could be subject to teperatures above 50 degrees C.

Life expectancy of hoses

There is no mention in BS 3212 of the life expectancy of hoses and it is not a requirement of these Standards that they be replaced after a fixed time. The age of the hose is not a failure point.

The date of manufacture is marked on the hose but this gives no guide to its condition as there is no way to determine when the hose was purchased and installed and it is impossible to know under what conditions it was stored before installation and what usage it has been put to since that date.

The BSS examination therefore requires a careful examination of the physical condition of the hose and its associated fastenings.

BS 5482-3 states that only type 2 hose should be used on boats as it has a higher specification for resistance to pressure, crushing, and permeation than type 1 hose.

Armoured hoses

Armoured hoses may be used providing they are identified by means of a permanently fixed tag or stamping on the swaged ferrule which clearly identifies the hose as type 2 of BS 3212.

If the armoured cover is damaged or corroded a fault will be recorded as damge of this kind to the metallic covering may result in damge to the flexible hose it is protecting.

Cylinder locker or housing drain hose

As drain hoses are not permanently charged with gas, it is not necessary for them to conform to BS 3212.

CHECKING

Visually check hose for signs of:

• leaks.
• flaws.
• brittleness.
• cracking.
• abrasion.
• kinking.
• joins.

Example image

The image to the right shows a commonly found cracked and perished flexible hose attached to the gas cylinder which should not be overlooked and replaced as soon as possible.

Length of hoses

Flexible hose shall be of the minimum practicable length, not exceeding 1m.

Minimum length

Flexible tubing should not be longer than necessary otherwise there is a risk of:

• kinking.
• snagging or trapping by other structures.

It must not, however, be too short to avoid any possibility of it being stretched and causing leaks at joints and connections.

The length and routing should also ensure that the bend radius is not be less than 5 times the outer diameter.

Accessibility

Flexible hose shall be ready accessible.

This enables the user to maintain regular checks on their cndition which is essential because they have a limited life and are susceptible to mechanical damage.

Installation

Flexible hose shall be installed without stress or tight radius turns.

It is important that flexible hose is properly installed without being subject to any poor installation practice which may cause damage or shorten the useful life.

Examples of such practice include twisting during tightening connections or forcing the hose to take up tight bends which may exceed the test requirements BS 3212.

These actions may cause damage to the hose wall and lead to premature aging or failure. BS 3212 requires a minimum bend radius of 5x the diameter of the hose.

Flexible hose passing through bulkheads, partitions, deckheads, or decks shall be protected from abrasion.

Risk from abrasion

Where flexible hoses pass through bulkheads, partitions, deckheads, or decks they must be protected from abrasion by the use of sleeves, grommets or other means.

Low pressure appliances

For low pressure applications, flexible hose shall be a pre-assembled length fitted with integral threaded metalic ends, or secured to nozzles by a metal crimped clip or a worm drive hose clamp.

Whatever method of connection is used, all componenets must be secure and incapable of movement and must show no signs of damage or deterioration.

Over-tightened clamps may distort the threads on the clamp rack and may lead to relaxation in the clamp tension and may damage the hose outer or inner linings.

Visually check hose clips and clamps for:

• security.
• corrosion.
• damage or deterioration.
• missing components.
• movement.
• freedom from burrs,rough edges.
• over-tightening.

Hose clamps

Hose clamps fixed by spring tension shall not be used.

Only hose clamps fixed by the use of tools must be used and clamps applied by hand and fixed by spring tension alone are not permitted.

Use of correct size clips & clamps

Hose clips and clamps shall be of the correct size for the hose and at least 8mm in width.

Clips and clamps must be of the correct size for the hose. In well designed hose clamps each diameter clamp will have a different radius at the underside of the rack. It is important that the radius range of the clamp is matched to the size of hose because the underside rack forms a signifcant part of the clamping circle. Oversized clamps become elliptical when tension is applied, rather than circular, and cause the wall of the hose to be pinched and possibly damged at the tensioning point. If the clamp is under-tightened the sealing ability will be reduced because of the ill-fitting rack.

PAGE STILL UNDER CONSTRUCTION.