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© ⅯⅯⅩⅢ Kirby Morgan Dive Systems, Inc. All rights reserved. Document # 130318002
Appendix 3 Supply Pressure Requirements & Tables
Kirby Morgan
®
37SS
Appendix 3
Supply Pressure Requirements & Tables
Table 1 should be used whenever low pressure
compressors are used or when using surface control
panels that are limited to outlet pressures within the
range of 220 psig or less.
It is important to insure the required outlet pressure
from the table can be maintained in a stable manner
at the surface to insure adequate supply at depth.
When used with high pressure consoles that can
regulate pressures greater than 220 psig use Appendix
3 Table 3 SuperFlow
®
/ SuperFlow
®
350 Regulator
High Pressure Regulated Source.
Diver Work Rates
The divers work rate, also known as respiratory min-
ute volume (RMV), is basically how hard the diver
breathes. As the diver’s physical exercise increases,
so does the ventilation rate. Proper training teaches
the diver to never push the work rate beyond normal
labored breathing. (This is in the 30-50 RMV range).
To put things in perspective, heavy work for a physi-
cally fit person:
Swimming at one knot is about
38 RMV
Running at 8 miles per hour is about
50 RMV
Once the diver hits 55 RMV, he is entering the ex-
treme range. Many fit divers can do 75 RMV for one
to two minutes providing the inhalation resistive ef-
fort of the breathing system is not much above 1-1.3
J/L. The divers work rate should never be so heavy
that the diver cannot maintain a simple conversation
with topside.
When the work rate gets into the moderately heavy
to heavy range 40-50 RMV the diver needs to slow
down!
Working to the point of being excessively winded
should be avoided at all costs!
Working at rates greater than 58 RMV underwater
is extreme, and can pose hazards that are not pres-
ent when doing extreme rates on the surface. When
underwater, inhalation and exhalation resistive effort
increases due to the density of the breathing gas and
resistive effort of the equipment. The increase in
resistive effort can cause an increase in blood level
CO
2
because the diver cannot ventilate as freely as
when breathing at the surface. When breathing air
at the deeper depths, nitrogen narcosis can mask
CO
2
symptoms which can then snowball into even
heavier breathing, often resulting in confusion, panic,
and in rare cases muscle spasm, unconsciousness,
sometimes resulting in death. In some rare cases high
ventilation rates has been suspected as the cause of
respiratory barotraumas, including arterial gas embo-
lism. The possibility of suffering a respiratory over
inflation event during high work rates while under-
water could be even greater for divers that smoke,
or have previous known or unknown lung disease or
respiratory damage. The safest course for the diver is
to keep the equipment properly maintained for peak
performance and to know and understand the capa-
bilities and limitations of the equipment including all
breathing supply systems they use.
The output capability of the supply system including
umbilicals should be known to all that use it and pe-
riodic tests should be done to insure flow capability.
Use Of Low Pressure Supply Table
The low pressure supply tables were developed to
simplify calculation of supply pressure. In order to
get the required volume to the diver, you need to have
the proper supply pressure. The table starts at 90 psig
and increases in 10 psig increments. The user simply
selects the lowest pressure that best represents the
low cycling pressure of the compressor being used.
The table basically shows the maximum depth that
can be attained while breathing at RMV’s (breath-
ing rates in liters per minute) listed. It is strongly
recommended that divers plan for a minimum supply
pressure that will allow the diver to work at no less
that 50 - 62.5 RMV.
