Pressures ranging from 2,600 to 3,000 psi will rupture
pressure. All regulators are marked with the name of
the safety disk and allow the gas in the cylinder to vent
the gas for which they are intended.)
to the atmosphere. This type of safety device is used in
To prevent leakage of gas above the valve stem
carbon dioxide service.
when the valve is opened, each valve is equipped with
asbestos, leather, rubber packing, or metal
4. BACKED SAFETY CAP WITH RUPTURE
diaphragms. Most valves have safety devices. (The
DISK--Backed safety caps with rupture disks are
safety devices for acetylene and ammonia are in the
essentially the same as those described in paragraph 3.
cylinders rather than in the valves.) These safety
However, the breakable disk is supported by fusible
devices consist of fusible metal plugs, rupture disks,
metal contained in the safety cap thus blocking off
or both. Spring-loaded safety devices are used for
escape ports. This cap works when the cylinder, valve,
some gases. If heat causes too much pressure, the fuse
and therefore the fusible metal are heated above the
plugs melt and the disks burst, releasing the contents
melting temperature. When the pressure within the
of the cylinder. Acetylene valves have screens in the
cylinder reaches 2,600 to 3,000 psi, the breakable disk
cylinder connections; other valves do not.
ruptures and reduces the pressure. This type of device
Valves manufactured according to the latest
is used commonly on air, argon, helium, hydrogen,
military specifications have the name of the gas, or
service for which they are designed. indented on at
least one of the flats on the sides of the valves. Valves
Lea king Valves
must be used only for the gases or fluids indicated.
Otherwise, personnel may be injured or the equipment
Cylinders with leaking or defective valves should
may be damaged.
be tagged as such and turned in to the nearest naval
supply depot for overhaul.
Safety Devices for Valves
Military specifications and ICC regulations
require that valves designed for certain services be
Cylinders, regulators, hoses, and torches are
fitted with safety devices. These devices guard against
important parts of the shop equipment for heating,
a buildup of hazardous pressures caused by heat. This
welding, and cutting. Learn and follow these safety
can easily happen with CO2 cylinders used for fire
rules for this type of equipment:
fighting in fire rooms and engine rooms. Pressure can
also build up from overcharging or similar causes.
Never fill a cylinder with a gas other than the
These safety devices may be divided into four general
gas for which it is specifically designated.
categories based on functional design as follows:
Never remove or change the decals.
1. FUSIBLE PLUGS--A fusible plug may be
Never return an empty cylinder without mak-
described as a threaded hex-head plug with a center
ing sure that valves are closed and that protec-
filled with fusible metal. When the cylinder is
tive caps are in place.
overheated, the fusible metal melts and permits the gas
to escape. This type of device is used on chlorine, freon,
Never drop the cylinders or let them strike
acetylene, and such gases.
against each other.
2. SPRING-LOADED SAFETY DEVICE--
Never use cylinders as rollers or supports.
These devices usually function as "pop" valves that
open to release excess pressure when pressure in the
Never hammer or strike the valve wheel to
cylinder overcomes spring tension. Devices of this sort
open or close the valve. Use only the wrenches
are used on liquefied petroleum gas valves. They
or tools approved for that purpose.
operate generally at about 150 percent of the cylinder's
If valve outlets are iced, use only warm water
to free them. Never use hot or boiling water.
3 . UNBACKED SAFETY CAP WITH
Never use a cylinder that IS improperly
RUPTURE DISK--This safety device is essentially a
marked; that is, where the paint color doesn't
safety cap that covers a safety port in the valve. The cap
agree with the information on the decal.
retains a breakable disk firmly over the safety port.