Name the three types of valves
Ball and Spring Valves
What are the three major clinical gases?
None of these are considered sterile
The operator supplies the energy to make it work, all or nothing mechanism
Ball and spring type valve
Also known as a regulator, reduces high pressure to low pressures, it helps to maintain a constant steady flow at lower pressures
Opens with pressure and closes with pressure, promotes unidirectional flow
What is the working pressure of the anesthesia machine?
A pipe or a chamber that has multiple openings to provide a point for making multiple connections?
What is the temperature below which a gas is converted to a liquid form by pressure?
What is the critical temperature of O2?
What is the critical temperature of N2O?
What is considered the intermediate pressure system?
Pipeline sources 50 psi
What is considered the high pressure system?
Cylinder sources, must have a regulator to down regulate the pressure from 1900 to operational pressure of anesthesia machine
What is the psi of a full e-cylinder?
What are the two common sizes of gas tanks?
E cylinder H cylinder (usually chained to the wall)
What is the purpose of a regulator?
Helps maintain flow without constantly changing the pressure
At what pressure will the anesthesia machine begin to malfunction?
If the pressure drops below 45 psi
What can contaminate the pipeline supply?
What is a common construction error related to the anesthesia machine?
Cross connection from construction error
What device should always be used on the anesthesia machine that can prevent delivering a hypoxic mixture?
Always use an O2 analyzer to avoid delivery of hypoxic mixtures to the patient
What safety system is used when connecting the gas hose to the wall outlet?
Key index safety system (KISS), they are uniquely colored and at the end of the hose there are different teeth that only fit to appropriate connector
What safety system connects the hose to the machine?
Diameter index safety system, each fitting has a different diameter and internal key unique for each gas
What type of valve prevents retrograde flow?
What is the purpose of the check valves?
When we use pipeline supply, the pressure will push the check valve off its seat and gas flows into the machine, however if pressure in the machine becomes greater than pipeline pressure, the check valve will close
How does the check valve affect the cylinder supply?
If the cylinder has a higher pressure than the pipeline supply the check valve will prevent the cylinder gas from backing up into the pipeline supply
What two safety systems only apply to the pipeline supplies?
Key index safety system KISS
Diameter index safety system DISS
What safety system is specific to the cylinders?
Pin index safety system PISS
What three colors are unique to Oxygen, medical air and nitrous oxide?
Oxygen - Green
Medical Air - Yellow
Nitrous oxide - Blue
What device measures the high pressure cylinder pressures relative to atmospheric pressure?
Bourdon Tube Pressure Gauge
What is the pressure in the tank when the bourdon gauge reads zero?
Atmospheric pressure (ambient depending on altitude)
What is considered the primary source of gases on the anesthesia machine?
Pipeline supply, cylinders are there to serve as emergency back up, not primary source
What determines how a gas is stored?
Its critical temperature
Safety system where there are holes in cylinder valve that fits two pins in the yolk
Pin index safety system PISS
How can the Pin index safety system be bypassed?
Multiple gaskets are used on the yoke
Elevate the cylinder beyond the pins
Pins could be filed off
Where are the index pins located for Air, Oxygen and Nitrous oxide?
Air 1 & 5
What is the purpose of the Safety relief device?
Built on top of the cylinders to prevent cylinder from exploding
What way should you turn the valve stem to open and allow gas to flow out?
What three devices can be used as the safety relief device?
Fragile copper disk
Fusible plug (Wood’s metal)
At what temperature does Wood’s Metal melt?
157-220°F, will melt and release gas from the cylinder
What Alloys make up Wood’s Metal?
Bismuth, lead, tin and cadmium
What US department is in charge on cylinder construction?
Department of Transportation
What US department used to be in charge of cylinder construction?
Interstate Commerce Commission
What are the seven markings required on a gas cylinder?
- Regulatory body (DOT) type and material
- Serial Number
- Purchase, user and manufacturer
- Manufacturer’s manual
- Manufacturer’s identity symbol
- Retest date, retester, ID symbol, 11% filling, ten year test interval
- Neck ring owners identification
What do the diamonds represent on a gas cylinder?
Green - non-flammable gas
Yellow - may be oxidizer
Red - flammable gas
What is the composition of a typical gas cylinder?
Entirely of steel and the walls are 3/8 inch thick
What would be a reason a gas cylinder was not constructed of steel?
MRI cylinders are constructed with aluminum because of the magnet
At what frequencies are the interior hydrostatic pressure of gas cylinders tested?
At least once every 5 or 10yrs
What are the testing conditions a gas cylinder must withstand?
Tested at 1.66 times (5/3) their service pressure
What department regulates the gases contained in the cylinder?
Food and drug administration
What department sets the standards for the potency and purity of the gas in the cylinder?
United States Pharmacopoeia
What organization sets the standards on safe practice of gas cylinders?
Compressed Gas Association (CGA)
What department is in charge of finding a location, construction and installation of bulk gas systems?
National Fire Protection Association (NFPA)
Why is it important to never oil cylinder valves?
The oil could aid in creating an explosion upon opening the cylinder
What is the proper way to store a gas cylinder?
Stored upright in a holder NEVER leaving it standing without support
What tool should be used when removing a cylinder from an anesthesia machine in order to prevent a leak?
Yoke plug, it guards against check valve failure
What is the proper way to identify a gas cylinder?
By its labeling, do NOT rely on its color
Why is it so important to slowly crack a gas cylinder open on the anesthesia machine?
In order to prevent an adiabatic compression ignition from occurring
What are the major risks of trans-filling gas cylinders?
Risk of compression ignition
Putting the wrong gas in the cylinder
What is the purpose of the hanger yoke?
Connects cylinder to machine
Provides unidirectional flow (Floating valve)
Ensures gas-tight seal
What is the purpose of the hanger yoke check valve?
Prevents reverse flow of gases, from one cylinder to another or from cylinder to pipeline
What is the function of the T-handle?
Pushes valve stem up against the hanger yoke, creates a nice tight seal after pins are properly aligned
When checking the anesthesia machine, what pressure must the oxygen cylinders be at in order to function if needed?
> 1000 psi
What will a N2O gauge read until the liquid is depleted?
This device maintains constant gas flow without changing the supply pressure
Pressure reducing device, takes high variable pressure and converts to low constant pressure
What is the capacity of a full oxygen cylinder?
What is the capacity of a full medical air cylinder?
What is the capacity of a full Nitrous oxide cylinder?
What determines how the gas will be stored in a cylinder?
If critical temp is below room temperature it will be stored as a gas, if the critical temp is greater than room temp it will be stored as a liquid