DESCRIPTION
Most chamber-equipped U.S. Navy units will have one of
five commonly provided chambers. They are:
1. Double-lock, 200-psig, 425-cubic-foot steel chamber (Figure
22-1).
2. Double-lock, 100-psig, 201-cubic-foot aluminum chamber. Two-lock chambers
of approximately 205-cubic-foot capacity or smaller may be used
as flyaway
or mobile chambers (Figure 22-2).
3. Double-lock, 100-psig, 202-cubic-foot steel chamber (ARS 50 class)
(Figure 22-3 and Figure
22-4).
4. Transportable Recompression Chamber System (TRCS) (Figure
22-5).
5. Fly Away Recompression Chamber (Figure
22-8, Figure 22-9, and Figure
22-10).
Basic Requirements. Double-lock chambers are
used because they permit tending personnel and supplies to enter and leave
the chamber during treatment. Where stated:
-
On-site chamber is defined as a certified and ready chamber accessible
withing 30 minutes of the dive site by available transportation.
-
On-station chamber is defined as a certified and ready chamber at the dive
site.
-
Emergency chamber is defined as the closest recompression chamber
available. A non-certified chamber may be used if the diving supervisor is
of the opinion that it is safe to use.
Chamber Volume. Navy chambers rated at the same pressure do not all have the
same physical dimensions, with the exception of the aluminum chambers, ARS 50
class chambers, TRCS, and FARCC. Consequently, internal volumes of steel
chambers are not standard and must be calculated for each chamber. Chamber
volume is normally provided with the chamber.
The basic components of a recompression chamber are much the same from one
model to another. They must be able to impose and maintain a pressure equivalent
to a depth of 165 fsw (6 atmospheres absolute). The piping and valving on some
chambers is arranged to permit control of the air supply and the exhaust from
either the inside or the outside of the chamber. Controls on the outside must be
able to override the inside controls in the event of a problem inside the chamber.
The usual method for providing this dual-control capability is through the use of
two separate systems. The first, consisting of a supply line and an exhaust line, can
only be controlled by valves that are outside of the chamber. The second air
supply/exhaust system has a double set of valves, one inside and one outside the
chamber. This arrangement permits the tender to regulate descent or ascent from
within the chamber, but always subject to final control by outside personnel.
Modernized Chamber. Modernized chambers (Figure
22-4) have carbon dioxide
and oxygen monitors, a CO2 scrubber system, a Built-In Breathing System
(BIBS), and an oxygen dump system which together reduce the ventilation
requirements. These chambers also include a chamber environment control system
that regulates humidity and temperature.
Transportable Recompression Chamber System (TRCS). In addition to the
chambers described above, a Transportable Recompression Chamber System
(TRCS) is currently in fleet use (Figure 22-5). The TRCS consists of two pressure
chambers. One is a conical-shaped chamber (Figure 22-6) called the Transportable
Recompression Chamber, and the other is a cylindrical shaped vessel (Figure
22-7) called the Transfer Lock (TL). The two chambers are capable of being
connected by means of a freely rotating NATO female flange coupling.
When a recompression chamber is required on site per Figure 6-14, or surface
decompression dives are planned, the full TRCS system (including both TRC and
TL) shall be on site.
When a recompression chamber is not required on site per Figure 6-14, the inner
lock (TRC) may be used for emergency recompression treatment.
Fly Away Recompression Chamber (FARCC). This chamber system consists of
a 60-inch double lock modernized chamber in a 20’ x 8’ x 8’ milvan (Figure 22-8
and Figure 22-9). The Fly Away Recompression Chamber (FARCC) also includes
a life support skid (Figure 22-10). In addition, a stand-alone generator is provided
for remote site power requirements.
Standard Features. Recompression chambers must be equipped with a means for
delivering breathing oxygen to the personnel in the chamber. The inner lock
should be provided with connections for demand-type oxygen inhalators. Oxygen
can be furnished through a high-pressure manifold connected with supply cylinders
outside the chamber.
Labeling. All lines should be identified and labeled to indicate function, content
and direction of flow. The color coding in Table 22-1 should be used.
Inlet and Exhaust Ports. Optimum chamber ventilation requires separation of the
inlet and exhaust ports within the chamber. Exhaust ports must be provided with a
guard device to prevent accidental injury when they are open.
Pressure Gauges. Chambers must be fitted with appropriate pressure gauges.
These gauges, marked to read in feet of seawater (fsw), must be calibrated or
compared as described in the applicable Planned Maintenance System (PMS) to
ensure accuracy in accordance with the instructions in Chapter 4.
Relief Valves. Recompression chambers should be equipped with pressure relief
valves in each manned lock. Chambers that do not have latches (dogs) on the
doors are not required to have a relief valve on the outer lock. The relief valves
shall be set in accordance with PMS. In addition, all chambers shall be equipped
with a gag valve, located between the chamber pressure hull and each relief valve.
This gag valve shall be a quick acting, ball-type valve, sized to be compatible with
the relief valve and its supply piping. The gag valve shall be safety wired in the
open position.
Communications System. Chamber communications are provided through a
diver’s intercommunication system, with the dual microphone/speaker unit in the
chamber and the surface unit outside. The communication system should be
arranged so that personnel inside the chamber need not interrupt their activities to
operate the system. The backup communications system may be provided by a set
of standard sound-powered telephones. The press-to-talk button on the set inside
the chamber can be taped down, thus keeping the circuit open.
Lighting Fixtures. Consideration should be given to installation of a low-level
lighting fixture (on a separate circuit), which can be used to relieve the patient of the heat and glare of the main lights. Emergency lights for both locks and an external control station are mandatory. No electrical equipment, other than that authorized within the scope of certification or as listed in the NAVSEA Authorized for Navy Use (ANU) List, is allowed inside the chamber. Because of the possibility of fire or explosion when working in an oxygen or compressed air atmosphere, all electrical wiring and equipment used in a chamber shall meet required specifications.
