AWABS - Gas supplies and cylinders Flashcards
(37 cards)
Older cylinders description
Thin walled
Seamless
Molybdenum steel
NOT MRI safe
Newer cylinders description
Aluminium alloy with fibreglass coating
MRI safe
Lighter weight
Information engraved onto cylinder
Information for label around shoulder of cylinder
Information from coloured plastic ring in neck of cylinder
How are cylinders tested
Gas cylinder / valve colour system and how stored
New system is that body of cylinder has to be white but colours on shoulder identify the gas
Note helium is brown and white (looks yellow on picture)
Also note Nitrous is “French blue”
Oxygen cylinder size categories and capacity
Use of knowing oxygen cylinder sizes
To calculate number of cylinders required for transfers etc
Size of oxygen cylinder usually on back of anaesthetic machine
Size E
Size of oxygen cylinder used in cylinder manifolds
Size J
Size of oxygen cylinders found in ambulances
Two size F cylinders are on ambulances
Newer / common oxygen cylinder size in hospital (aluminium alloy and fibreglass cylinder rather than molybdenum steel cylinder)
Size CD -smaller in size than size D but higher capacity as higher pressure
460 L capacity
Stored at 23,000 kPa
“Only” oxygen cylinder not stored at 13,700 kPa
A newer version of the D cylinder with an integrated valve
Capacity of nitrous cylinders compared to oxygen cylinders
Store higher capacity than oxygen
How to calculate cylinder contents
Why Nitrous and CO2 (stored as liquids) need to be measured by weight
Pressure remains constant until all liquids used up as when liquid is at saturated vapour pressure
Critical temperature definition
Temperature ABOVE which a substance cannot be liquified, no matter how much pressure is applied
(will remain in gaseous state)
Critical temp of O2
-118.6 degrees
(often rounded to -119 degrees)
Critical temp if NO
36.5 degrees
Critical temp of CO2
31 degrees
Pseudocritical temperature definition
The temperature BELOW which there is a risk that a gas mixture will separate out into its constituent parts
(Occurs in gas mixtures eg Entonox)
Pseudocritical temperature of Entonox
-5.5 degrees
What happens if a gas mixture falls below pseudocritical temperature and clinical implication
How to reverse gas mixture separation
Re-warming and mixing
