Mailing List Archive Mailing List Archive
Subject:Cylinder Capacities Sent on: 6/4/95 11:35 am
Some time ago I asked about working pressures of smaller US size cylinders -
this was to extend a table I had produced to convert the cubic foot / working
pressure system in US to the water capacity system used throughout most of
Europe. Unfortunatly it turned into a cubic foot versus bar/WC war and I never
got the info I requested :-)
But many asked that I publish the table that I had previusly worked on - so
please find it below. If any one spots a mistake please Email me and I can
correct it.
Cylinder Capacities
Many of us dive abroad and have to suffer the vagaries of the USA system of
cylinder capacities. The USA system is based around the capacity of the
cylinder (in cubic feet) at a defined operating pressure (in PSI). The real
problem comes from the changing operating capacities of the cylinders (i.e. a
80 Cubic foot aluminium cylinder is rated at 3000 PSI, whereas a 104 Cubic foot
steel cylinder is rated at 2600 PSI) and the possibility that a cylinder may
not be pumped to its exact working pressure (due to under/over filling).
For those of us who keep a note of the Starting and ending cylinder contents,
so that we can calculate and record our Surface Breathing rate this is a
problem. In addition we may have hired equipment which has a contents gauge in
PSI or have taken our own, calibrated in BAR and are mixing the two systems.
To make my life easier I sat down and calculated the following table, which
takes the USA standard cylinders and equates them to the water capacity and
operating pressure system we use in the Europe.
Capacity in Working Pressure WC
Cubic Feet PSI BAR Litre
50Al 3100 210.8 6.7
71.2 St 2470 168.0 12.0
80 Al 3000 204.1 11.1
80 Gen 3500 238.1 9.5
1OOAl 3300 224.5 12.6
95 St 2640 179.6 15.0
100 Gen 3500 238.1 11.9
104 St 2640 179.6 16.5
120 Gen 3500 238.1 14.3
Key Al = Aluminium: St = Steel: Gen = Sherwood Genesis
Some other useful conversion figures which are
PSI to BARS divide by 14.7
Litres to Cubic feet multiply by 0.035
Mail Address : graeme_davison@ne*.co*
British Sub Aqua Club : 1958 Under Pressure
BSAC : Advanced Diver
IANTD : Advanced Nitrox
NSS-CD : Cavern / Intro Cave
Dive Safe - Dive Nitrox !
Navigate by Author:
[Previous]
[Next]
[Author Search Index]
Navigate by Subject:
[Previous]
[Next]
[Subject Search Index]
[Send Reply] [Send Message with New Topic]
[Search Selection] [Mailing List Home] [Home]