Errors partV

Abstract

Here, in Part V, we give only a short comment about pressure units and the various conversion factors used in diving medicine books, as the majority of these books are using imperial units like pounds per square inch (psi) or feet of seawater (fsw), but for serious scientific publications or technical documentation the SI system, the „International System of Units“ is the preferred and used system.

These conversion factors are regularly not consistent over all these books as they normally do not specify (water-)temperature nor the density. So they are at times even contradicting and one thing for sure for a physician, i.e. a physical layman: confusing!

For an easy and quick assessment with mental arithmetic, say for a ballpark to check absolute pressures, partial pressures of oxygen and the like, especially when required underwater, during real diving, SI is the system of choice.

Full text

1
The diving medical detectives:
when diving medicine books
are completely wrong
02.02.2023, Part V:
On pressure units
Miri Rosenblat, TAU
Nurit Vered, Technion Haifa
Albi Salm, SubMarineConsulting
DOI:

2
The diving medical detectives:
when diving medicine books
are completely wrong, Part V:
On pressure units
Abstract & Methods: the same, as per Parts I to IV of this series.
Part I, Ref. [1], DOI: 10.13140/RG.2.2.15199.79528
Part II, Ref. [2], DOI: 10.13140/RG.2.2.35722.39366
Part III, Ref. [3], DOI: 10.13140/RG.2.2.28043.62245
Part IV, Ref. [4], DOI: 10.13140/RG.2.2.12077.97760
If you want to contribute s.th. to our list, we would be very happy if you send
an e-mail to our head of lab: director@smc-de.com
(That is: to be continued in 2023 with Part VI ☺)

3
The diving medical detectives:
when diving medicine books
are completely wrong, Part V:
On pressure units
Here, in Part V, we give only a short comment about pressure units and the
various conversion factors used in diving medicine books, as the majority of
these books are using imperial units like pounds per square inch (psi) or feet
of seawater (fsw), but for serious scientific publications or technical
documentation the SI system, the „International System of Units“ is the
preferred and used system.
These conversion factors are regularly not consistent over all these books as
they normally do not specify (water-)temperature nor the density. So they are
at times even contradicting andone thing for sure for a physician, i.e. a
physical layman: confusing!
For an easy and quick assessment with mental arithmetic, say for a ballpark
to check absolute pressures, partial pressures of oxygen and the like,
especially when required underwater, during real diving, SI is the system of
choice.

4
The mother of all diving manuals world-wide,
the United States Navy Diving Manual, with the very wise
remark, that 10 m is not 10 msw and: 10 feet is not 10 fsw!
On p. 2-33 of Ref. [15 e]
US DIVING MANUAL_REV7_ChangeA-6.6.18 ,
Free download @: http://www.divetable.eu/15.pdf

5
[62] "Diving & Subaquatic
Medicine", Carl Edmonds,
Lowry, Pennefather,
Walker, 4 th. Ed., Arnold,
ISBN 0-340-80630-3
On p. 12: with useful
ballparks, just sufficient
for medical
assessments.
And another
wise remark
concerning
temperature &
salinity!

6
[63] "Bennett and Elliott's Physiology and
Medicine of Diving" Alf Brubakk, Neuman et al.,
5 th Ed. Saunders,
ISBN 0-7020-2571-2
In the chapter
“Decompression Practice”
from Bill Hamilton and
Ed Thalmann we find the
following clarifying hints
on p. 457:

7
[63] "Bennett and Elliott's Physiology and
Medicine of Diving" Alf Brubakk, Neuman et al.,
5 th Ed. Saunders, ISBN 0-7020-2571-2
In the appendix on p. 760
is the following matrix
(excerpt):

8
[158] Shilling, C. W. Carlston, C.B. Mathias, R.A (1984) The
Physician's Guide to Diving Medicine, Plenum Press, N.Y.,
ISBN-13: 978-1-4612-9663-8, p. 36:
And then, on p. 50, concerning the average density of seawater (citation):
“… 1.026 g/cm3@ 15°C.”

9
The next 4 slides are just screen shots from various books:
the conversion factors for the various pressure units
sometimes far out in the left field.
The yellow display is ours:

10
[75], Bove and Davis‘ Diving Medicine,
4th. Edition, p. 575, Appendix I
(truncated)

11
[248], Strauss, R.H.
(ed.)(1976) Diving Medicine,
Grune & Stratton, Inc., N.Y.,
ISBN 0-8089-0699-2
on p. 348:

12
[110] The Underwater Handbook:
A Guide to Physiology and
Performance for the Engineer;
Shilling, Werts,
Schandelmaier;
Plenum Press N.Y.,
1976, ISBN 0-306-30843-6
A very complete matrix,
with high precision, on p. 893,
but not without flaws …
(pls. cf. next slide)

13
[110] p. 893:

14
Conclusion / Advice:
If possible, use the SI system.
If not, use the ballparks from
[62] on p. 12:
these are sufficient for all
practical purposes:
they will match the average
precision of all
depth gauges, dive computers
or oxygen analyzers.
For scientific accuracy needed in
meticulous calculations, say in a
decompression algorithm or for
adeep saturation dive, check for
the set of conversion factors you
picked the (water-)temperature and (water-)density they are defined for!
And then: Double Check!!!
if they fit your intended environment!

15
References (1):
We from the lab (Miri, Nurit & Yael) rely heavily on the
knowledge & experience of our boss:
https://www.researchgate.net/profile/Albi-Salm-2
As well we have our big library at hand:
http://www.divetable.eu/BOOKS/index.htm יבלא: הבר הדות!
ירימ ,לעיו תירונ
[15 e] US DIVING MANUAL_REV7_ChangeA-6.6.18
[62] "Diving & Subaquatic Medicine", Carl Edmonds, Lowry, Pennefather,
Walker, 4 th. Ed., Arnold, ISBN 0-340-80630-3,
[63] "Bennett and Elliott's Physiology and Medicine of Diving" Alf Brubakk,
Neuman et al., 5 th Ed. Saunders, ISBN 0-7020-2571-2
[75], Bove and Davis‘ Diving Medicine, 4th. Edition

16
References (2):
[110] The Underwater Handbook: A Guide to Physiology and Performance for
the Engineer; Shilling, Werts, Schandelmaier; Plenum Press N.Y., 1976, ISBN
0-306-30843-6
[158] Shilling, C. W. Carlston, C.B. Mathias, R.A (1984) The Physician's
Guide to Diving Medicine, Plenum Press, N.Y., ISBN-13: 978-1-4612-9663-8
[248] Strauss, R.H. (ed.)(1976) Diving Medicine,
Grune & Stratton, Inc., N.Y., ISBN 0-8089-0699-2

17
References (3):
„The diving medical detectives-series on ResearchGate:
when diving medicine books are completely wrong!”
Parts # 1 to 4:
[1] Salm, A. (09.09.2021) DOI: : 10.13140/RG.2.2.15199.79528
[2] Salm, A. (17.09.2021) DOI: 10.13140/RG.2.2.35722.39366
[3] Salm, A. (01.12.2021) DOI: 10.13140/RG.2.2.28043.62245
[4] Salm, A. (06/2022) DOI: 10.13140/RG.2.2.12077.97760