From the old CME manual we Auxiliary Vessel Examiners used, prior to the advent
of Vessel Safety Checks, here is the applicable text on galley systems.

a. CME Requirements. There is no federal regulation concerning galley
equipment on recreational boats.
b. Liquefied Petroleum Gas (LPG) Systems. LPG includes any product
predominantly composed of propane, propylene, butanes, or butylenes. Although
LPG is two phased (liquid/vapor), under normal atmospheric pressure it is in
the gaseous state. Under a pressure of about 240 psi, it liquefies. Upon its
release from pressure it then vaporizes again. It is heavier than air and will
fall and settle if released. It is also known as "bottled gas" and contains a
distinctive odorant that will indicate a leak is occurring.
c. Compressed Natural Gas (CNG) Systems. Compressed natural gas (CNG)
is natural gas that is normally supplied as a fuel by a gas utility. It is
stored in a portable cylinder which may reach a pressure of 2250 psi. CNG is
lighter than air and will generally rise and diffuse into the open air unless
trapped by pockets or partial enclosures in the cabin structure of the vessel
where there is no forced ventilation. In such cases a 4% to 5% gas-to-air ratio
by volume will constitute an explosive mixture. To alleviate the potential for
an explosive mixture, some means of overhead ventilation must be provided. The
gas itself must contain a distinctive odorant that will indicate a leak is
occurring.
d. LPG/CNG Equipment Requirements.
(1) The LPG gas cylinder (including any empty or reserve
cylinders) and regulating equipment must not be installed in closed
compartments, or compartments that can be easily closed. They must be located
so that escaping vapor cannot reach enclosed spaces. It must be substantially
secured and readily accessible. The cylinder must be equipped with a manual
shut-off valve with a hand wheel attached so it can be closed without the use
of a separate wrench (a dual cylinder system shall be provided with a two way
positive shut-off valve at the cylinder manifold). To be readily accessible
the cylinder must be located so that the hand wheel can be conveniently and
quickly operated. If the cylinders are enclosed in a storage locker, the
determination of "readily accessible" will be made with the compartment open.
(2) LPG cylinders may be stowed in a protective enclosure topside.
If such an enclosure is used it must be so constructed to provide convenient
and quick access to the shut-off valve. Permanent ventilation openings shall be
located in the bottom of the enclosure.
(3) Boat construction or design preventing the above, the
cylinder, regulating equipment, and safety equipment shall be mounted in a
locker or housing that is vapor-tight to the hull interior and located above
the waterline in an open cockpit. The locker or housing must be constructed of
or lined with corrosion-resistant material and shall open only from the top by
means of a cover seated on a gasket and tightly latched but capable of being
conveniently and quickly opened for operation of container valves and for
testing the system for leakage. It shall also be vented by a pipe of at least
1/2 inch internal diameter, led outboard. The vent opening shall be at the
bottom of and terminate at a point lower than the locker or housing bottom, but
be above the waterline.
(4) The LPG system must be equipped with a regulator to reduce the
gas from the cylinder pressure down to the operating or line pressure. It must
be substantially secured outside the enclosed spaces of the vessel and it must
be readily accessible. The regulator shall be located in such a position that,
in the event of component failure, it will discharge into the open atmosphere.
The point of discharge shall be at least two feet from any opening to the
cabin, the hull interior, or from an engine exhaust. LPG Storage Tank and
Regulating Device
(5) CNG gas cylinders (including any empty or reserve cylinders)
and regulating equipment shall be located in a well ventilated area. The area
shall provide protection from water or mechanical damage. The cylinders and
regulating equipment shall be readily accessible and secured (in vertical or
horizontal position). The CNG cylinders shall not be installed in compartments
containing an internal combustion engine. CNG cylinder storage compartments
shall not have openings which communicate with the engine space above the level
of the pressure regulator. The cylinder location shall be readily accessible
such that the cylinder valve hand wheel can be conveniently and quickly
operated. A pressure gauge is required on the high side of the system and the
dial must be fully visible. Compartments and lockers in which CNG cylinders
are stored shall have a ventilation opening located above the cylinders. There
must be two regulators to reduce gas pressure to operating line pressure. The
pressure regulators must each have a safety relief vent tube installed which
will direct escaping gas overboard above the water line. The vent hole shall be
protected against entry of water or other foreign material.
CNG Cylinder and Regulator
**NOTE** A pressure gauge is recommended but NOT required.
(6) LPG and CNG systems on vessels carrying passengers for hire
must have a remote shut off valve if the supply line enters an enclosed space.
A valve must be installed that can be operated from a position adjacent to the
appliance. The valve must be located between the fuel tank and the point where
the fuel supply line enters the enclosed portion of the vessel. A power
operated valve installed to meet this requirement must be of a type that will
fail closed.
(7) LPG and CNG systems on vessels carrying passengers for hire
must have a pressure gauge on the high pressure side of the supply line.
(8) Each CNG regulator assembly must also be fitted with a
pressure gauge. The gauge serves to show the amount of fuel remaining in the
cylinder and it provides an easy way to test the system for leaks. The gauge
must be located so that it is easily readable.
(9) The owner/operator can be advised of the proper procedures for
performing a leak test as follows:
(a) Close all appliance valves.
(b) Open cylinder valve to pressurize system.
(c) Close cylinder valve and read pressure gauge.
(d) Read pressure gauge again in 15 minutes. If there is no
pressure loss it is assumed there are no leaks.
(10) The entire system must be free from leaks.
(11) Advise the owner/operator to test the entire system at least
monthly using the above procedure. Suspected leaking areas can be traced with
a soapy water solution.
* * * *
* * *
DO NOT FLAME TEST FOR LEAKS!!
(12) All lines must be routed so that they are protected against
physical damage. Wherever lines pass through decks or bulkheads, they must be
protected by close fitting ferrules made of non-abrasive material. The fuel
supply line system and its components shall be designed to be specifically for
LPG/CNG and to withstand stress and exposure to the marine environment.
(a) LPG fuel supply lines must be one continuous length of
either copper tubing or UL labeled hose. They are not the same as tubing for
CNG.
(b) CNG fuel supply lines must be one continuous length and
marked or otherwise identified to indicate suitability for CNG.
(c) CNG has a corrosive effect on copper. Copper and copper
alloy materials are prohibited within any CNG system
NOTE*
* Internally tinned copper tubing is approved for use with CNG and is used
regularly. This tubing looks like copper from the outside. It must be marked
as suitable for CNG.
(13) All appliances must be positioned and shielded so that no
flammable material is in close proximity or could be ignited by the appliance.
(14) The compartment in which a gas appliance is located must be
adequately ventilated. The Vessel Examiner will determine that the compartment
can be ventilated by open hatches, ports, or air flow created by the craft's
ventilation system.
(15) If the LPG/CNG installation has more than one appliance,
assure that separate fuel supply piping is routed from the cylinder to the
appliance. Any "TEE" fittings installed for fueling more than one appliance
must be installed at the cylinder, down stream of the regulator, not behind the
appliances or in the bilges. Fittings of dissimilar metal to the fuel tubing
must not be exposed to water or electrolysis will result.
(16) LPG/CNG stoves may be fitted in gimbals to assure that the
appliance remains upright when the vessel rolls. A length of UL labeled
flexible hose, suitable for the fuel in use, shall be installed at the end of
the fuel supply line on these gimbal mounted appliances. LPG/CNG labeled hose
is required by the National Fire Protection Association and American Boat and
Yacht Council standards for LPG/CNG installations.)
(17) These guidelines apply to LPG and CNG systems on
recreational boats only; as there are NO federal regulations concerning
galley equipment on recreational boats.
(18) Refer to paragraphs O.2.d.(6) and (7) for special shut off
valve requirements for vessels carrying passengers for hire.
(19) Caddy Pack stoves using detachable 8-ounce butane canisters of
fuel will be acceptable IF the stove is permanently attached to the counter or
gimbled shelf in the galley. The use of suction cups on the legs is not
acceptable as the suction may release and allow the stove to move. The fuel
canister must be detached from the stove when it is not in use. Extra
canisters of fuel must be stored in such a manner that they do not roll around
in heavy seas. Fuel canisters larger than 8-ounces are not acceptable for this
type stove.