Compressed gasses Flashcards
Psi
pounds per square inch
Non-liquified gas
A gas that does not liquefy at ordinary ambient temperatures regardless of the pressure applied
Common carrier gasses used
Oxygen
Nitrogen
Air
Helium
Liquified gas
A gas that becomes liquid to a large extent in containers at ambient temperature and at pressures from 25-1500psi
Gasses that stay in liquid gas form
Nitrous oxide
Carbon dioxide
Who governs purity
FDA
Who governs marking, labeling, storage, handling
DOT
Who governs employee safety
Dept of Labor/OSH
Who governs the risk of combustion
National Fire Protection Association
Body of compressed gas tanks componenets
Steel, steel carbon fiber, aluminum
Flat or concave bases
Neck with screw threads;
What Allows refilling and discharge of gas tanks? and what types can they be
Valve
Attached to the neck
Bronze or brass
What should be attached to every cylinder?
Handle
Opens/closes cylinder
What Vents cylinder contents to atmosphere if pressure increases to dangerous level?
what types can they be?
Pressure relief device
Disc or plug
Holes on the cylinder valve
positioned in an arc below
the outlet port
Pin Index Safety System
Pins on the ______ or _______are positioned to fit
into the pin index safety system holes on the neck of the gas cylinder
Pins on the yoke or pressure
regulator are positioned to fit
into these holes
What letter code is the smallest cylinder size
Letter code….”a” smallest
Most common cylinder used in anesthesia machines
E most commonly on anesthesia machines
What cylinder size is for transport
D for transport
Oxygen pressure and volume range when full
pressure 1900-2200psi
volume 600L
Non-liquefied gas contents vs pressure
pressure decreases as volume decreases
Contents vs Pressure for liquefied gas
pressure depends on vapor pressure
NOT an indication of remaining volume
DOT regulations for cylinders (5)
-Service pressure
-Test date
-Diamond-shaped label indicating hazard of gas…danger, warning, or caution
-Name and address of the manufacturer
-Expiration date of contents
Valves, regulators, gauges never come into contact _____________ (3)
Valves, regulators, gauges never come into contact with oils, greases, lubricants
don’t use lubricant to open valves
Never subject cylinders to temps ________
Never subject to temps above 54 C (130F)
Never cross-use what for cylinders?
Never cross-use hoses, regulators, gauges
Cylinder Standards (8)
Valves, regulators, gauges never come into contact with oils, greases, lubricants
Never subject to temps above 54 C (130F)
Connections always tight
Never cross use hoses, regulators, gauges
Markings, labels must not be altered
Cannot be dropped, drug, slid
Valve kept closed at all times
Properly secured to prevent fall
Cylinder valves are to be kept_______
Valve kept closed at all times
nitrous colors
blue
air colors
yellow
oxygen colors
green
Storage rooms for cylinders requirements (6)
Adequate ventilation
Signs “no smoking” “no combustibles”
Not exposed to corrosive chemicals, fumes
Stored upright in bins
Full separated from empty
Wrapping, drapes undesirable
How to use a cylinder; (8)
Label, pin index holes, regulator, valve outlet inspected
Tamper seal removed
1 Washer in place
Open valve before bringing cylinder to pt
Face valve outlet away from people
Open slowly
Check service pressure
Correct leaks if any
Open _____ before bringing_____ to pt
Open valve before bringing cylinder to pt
Used to deliver non-flammable gases to anesthetizing locations and other patient care areas
Pipeline Systems
Pipeline system delivers what gasses?
oxygen
nitrous
air
Oxygen bank supply requirement
A “bank” must contain at least 2 days supply
Have primary and secondary bank
May have reserve supply in secondary location
Central supply locations
Outdoors in enclosure
Indoors in secure area
What is the gaseous supply cylinder size
Gaseous supply
G and H cylinders
Refilled on site or transported
Liquid gas supply features
Less expensive and more
convenient to store
Refilled from supply trucks
No interruption to service
Main lines piping
connect gas source to risers
Riser
vertical pipes connecting main line with branch lines on each level of the facility
Branch piping
sections supplying a room or group of rooms on one level of the facility. stem of risers
Permit specific areas of the piping system to be isolated for problems /maintenance
Shut-off Valves
Where are area alarm systems located?
Found in critical life support
areas
Must be audible and visible
Must be labeled for gas and area
What causes area alarm systems to alarm
Alarms if pressure increases/
decreases 20% from normal
line pressure
Area alarm systems that must alarm at least ______ places
Must alarm in at least 2 places…
Maintenance, engineering, the affected unit
Point in piped gas distribution where user connects and disconnects by hose
Terminal units
What system does terminal units use?
Uses Diameter Index Safety System (DISS) or “quick connects”
Nipple and nut vary in bore and diameter
Allow connection with one/both hands without tools
Quick Connectors
What is More convenient but leak more than terminal units
Quick Connectors
Outlet Types
Wall, Ceiling-mounted, Ceiling column
Modern volatile anesthetics exist in_______ (3)
Exist in liquid state below 20 degrees C
(68 degrees F)
In closed container, molecules escape liquid to vapor phase
Vapor molecules bombard container walls…saturated vapor pressure
Part of the total pressure of any one gas in a mixture
Partial Pressure
Partail pressure depends on____
Depends on temperature
Daltons law
(remember partial pressures = sum…Dalton’s law)
Concentration of a gas in a mixture expressed as a percentage
Volumes Percent
Partial pressure/total pressure = volumes percent
When equilibrium is achieved between the liquid and vapor phases at a constant temperature
Vapor pressure
From molecules hitting walls of container
Vapor pressure is dependent on……
Characteristics of liquid
Temperature of liquid
Vapor pressure is_________ of atmospheric pressure
Independent of atmospheric pressure
Gas phase above liquid contains all the vapor it can hold
Saturation
Pressure exerted by vapor is ______
“saturated vapor pressure (SVP)”
Halothane trade name and vp
fluothane
243
Enflurane trade name and vp
Ethrane
175
Isoflurane trade name and vp
forane
238
Desflurane trade name and vp
suprane
669
Sevoflurane trade name and vp
Ultane
157
Temperature at which vapor pressure equals atmospheric pressure
Boiling points
the number of calories necessary to convert 1G of liquid into vapor (or 1ml of liquid to vapor)
Heat of vaporization
As carrier gas flows through vaporizer, vapor molecules leave»»>
Equilibrium shifts…more molecules in liquid state-> Liquid temperature drops causing vapor pressure to drop. Output of vapor decreases
Specific Heat
Number of calories required to raise the temperature of 1 g of a substance 1degree C
The_____ the specific heat, the ______ temp of the substance
The higher the specific heat, the more heat required to raise the temp of the substance
What is the standard for specific heat
Water is the standard….1cal/g
What to Considered when choosing material for vaporizer
How much heat must be supplied
Materials with higher specific heat minimize temperature variations
The ‘speed’ at which heat flows through a substance
Thermal Conductivity
The ______ the thermal conductivity, the______ the substance conducts heat
The higher the thermal conductivity, the better the substance conducts heat
Metals with______ thermal conductivity______ temperature swings during vaporization
Metals with high thermal conductivity minimize temperature swings during vaporization
Metals with best thermal conductivity
Copper
Aluminum
What is the vaporizer made of
copper or aluminum
A device that changes a liquid anesthetic agent to a vapor
Vaporizers
adds a controlled amount of that vapor to fresh gas flow in the breathing system
Vaporizer Design
Concentration-calibrated, variable bypass
variable; some goes to the vapo and some goes by it (splitting ratio)
Vaporizer is located ________
Located between flow meter and common gas outlet
Vaporizer may not be_______
May not be past common gas outlet
Vaporizers are not calibrated for_____
Are not calibrated for high flows of oxygen flush
“Method of regulating concentration of volatile from vaporizer”
Variable Bypass Vaporizers
Vaporizer dilutes saturated vapor by splitting gas flow
Ratio depends on size of adjustable orifice
”splitting ratio”
Variable Bypass Vaporizers types
”Flow-over” vs “bubble-through”
Splitting ratio changes as temperature changes
Manual or automatic temperature compensation
Fix for incorrect agent
Must be completely drained and all liquid discarded
FGF run until no vapor is detected
Should see monitor detect 2 vapors
At low flow rates ________
(<250ml/min)
Output < setting
High density of volatile prevents upward movement of molecules (less likely to move from liquid to gas form)
At high flow rates_______
(>15L/min)
Vapor Output < setting
Failure to saturate carrier gas
Intermittent back pressure pumping effect with……
Positive pressure ventilation
Oxygen flush valve
Pumping effect is more pronounced with ______ (3)
Low flow rates
Low dial settings
Low levels of liquid in vaporizing chamber
Measures to attenuate pumping effect (4)
Smaller vaporizing chambers
Baffle systems
Longer tube for the inlet of vaporizing chamber
Addition of check valve
High FGF effect on rebreathing
little exhaled gas rebreathed
Inspired concentration = vaporizer setting
Low FGF or high Vm effect on breathing
significant rebreathing
Difference between vaporizer setting and inspired concentration
vapor pressure is _______ of barometric pressure
vapor pressure is independent of barometric pressure
Vaporizers are calculated at_______
sea level
If altitude increases how does that affect the anesthetic delivery
Volumes % of volatile ↑ significantly in vaporizer
Partial pressures of gases changes lesser
…anesthetic depth is partial pressure in BRAIN
How does tipping affect the vaporizers?
Excessive liquid enters bypass chamber
Excessively high output
What isolates vaporizer and bypass chamber
Some Drager vaporizers
“transport dial”…isolates vaporizer and bypass chamber
Effects of overfilling
Liquid can enter bypass chamber
Excessive dose delivered to patient
Modern vaporizers
Design prevents overfilling
Overflow hole
What can cause leaks in the vaporizer? (3)
Loose filler caps
Drain valves
Vaporizer/mounting bracket interface
Signs of leak from vaporizer (3)
-Odor of gas
-Lower than expected inhaled concentration (Fi)
Consequences
-Patient awareness
Average concentrations of vaporizers
Average concentrations +/- 20% of setting
Output of vaporizer______ OFF
Output of vaporizer <0.05% in OFF
All control knobs on vaporizer are ______
counterclockwise
Vaporizer Standards (6)
Average concentrations +/- 20% of setting
Gas may not pass through more than 1 vaporizer
Output of vaporizer <0.05% in OFF
All control knobs counterclockwise
Filling levels displayed
Can’t overfill when in use
Vaporizer Mounting Standards (4)
Detachable
Locking lever on back
Easily removed and replaced (esp. for MH)
Locks easily stick and jam
What makes the seal on the mounting bracket?
Weight of vaporizer and “O” ring create seal
Prevents more than 1 vaporizer from being turned ON at a time
Interlock Device
