In part three of this three-part series, we conclude our discussion of cylinders.
Complete Show Notes
2:45 High-Pressure Regulators
- Most regulators are specific to certain Compressed Gas Association (CGA) valves in terms of classification
- CGA takes gasses with similar characteristics and defines relationships between valves and the chemical-physical properties of a cylinder’s contents
- Standard regulators have 4 parts: 2 gauges and 2 knobs
- Gauge closest to the cylinder gives you the pressure inside the tank
- Second gauge gives you the working pressure
- Knob between the two gauges controls the amount of product going into the system
- Other knob controls the pressure the product wants to reach once it’s flowing
4:45 Labels and Markings
- These will be hard-stamped into the cylinder
- If you’re dealing with a rusted cylinder, use a piece of paper and a pencil to make out the label
- First line of information (similar to a VIN number):
- Identifying information
- In some cases, you’ll see “ICC” (Interstate Commerce Commission) information – dates back before the DOT was even created, so you know you’re dealing with an old cylinder
- Alternately, the tank might have “DOT” (Department of Transportation) information – modern CFR data that covers all modern cylinders in the U.S.
- Codes that tell you what the cylinder is made of – this is important because it helps you determine compatibilities and how the cylinder will react
- There’s close to 100 different recipes out there for creating cylinders – check out the CGA or look it up on Google
- Maximum allowable working pressure (MAWP) information is next to the material stamp
- Identifying information
- Keep an eye out for hydrogen – if you see an “H,” it means the cylinder’s metal is designed to hold hydrogen
- Hydrogen embrittlement – when hydrogen is placed under pressure in the presence of carbon steel – the hydrogen actually goes into the metal and makes it crack
- Because hydrogen is the smallest element, it can easily slip into different metals – it gets through atoms and shears the bonds between them, which contributes to embrittlement
- You might see this in homes – people are trying to generate hydrogen and use it to live off the grid
- Second line of information:
- Serial number
- Includes manufacturer abbreviations and symbols
- Series of dates
- These start off with the manufacturer’s inspection date and also include the hydrostatic test date – most cylinders are tested every 5 years
- If you see a star, it only has to be tested every 10 years – some symbols allow the cylinder to be tested even more infrequently
- Serial number
14:30 On-Scene Evaluations and Questions to Ask
- Questions to ask yourself and others:
- What was the mechanism of injury?
- Why were we called today?
- Is it on fire? If so, what kind of heat is involved? How bad is it?
- What’s in the cylinder? Are the contents attacking the cylinder?
- What type of metal is on the inside of the tank?
- Did the pressure relief device go off? Is it currently going off? Is it stuck because it’s going off?
- What’s the general structural integrity of the tank? Are there any scratches, dents, gouges, scrapes, or rust (all referred to as “insults”)? Are there welding issues?
- What are the manufacture and hydrostatic dates? If you don’t have the hydrostatic date, you don’t know the cylinder’s structural integrity – you can also assume the tank wasn’t well taken care of
- Where is the cylinder leaking? If it’s leaking where the valve connects to the tank, there’s really nothing we can do – don’t try to tighten it down, because it’s leaking for a reason and we shouldn’t mess with it
- Can we cap or plug the threading area to stop the leak? This may not be your best option if the tank has been illegally converted
- Will opening and re-closing the valve solve the problem? In many cases, the valve isn’t working because something small is keeping the valve from closing the whole way – letting some air out can get rid of this obstruction
- Is the packing nut snug? If it’s tight, you won’t be able to open or close the valve – it just needs to be leak-proof
- If your department doesn’t have a temp gun, go buy a cheap one ASAP – doesn’t have to be top-of-the-line
- Don’t run the cylinder down to zero – leave 10-20% of pressure inside the container to “save” it from damage since you may be keeping it
- Cylinders can last for a long time (only a few have a 25-year life expectancy) – for the most part, cylinders can last almost indefinitely up to the 100-year mark
26:10 Containment with Cylinder Coffins
- Giant cylinder that you put the problematic cylinder into
- Designed specifically to hold a leaking cylinder
- Some gasses can’t be used with a cylinder coffin
- Acetylene is too unstable – there’s no packing in cylinder coffins, which is problematic and unsafe
- Once the cylinder is in the cylinder coffin, you can evacuate it in a controlled manner – valving on cylinder coffin is specifically designed to offload the product
- Several types of cylinder coffins out there – they’re all designed to hold specific chemicals that have their own specific chemical-physical properties
- Types of cylinder coffins include stainless steel and carbon steel
- Most industries have their own specific cylinder coffins set up for their own emergency use – identify where these are so you’re prepared
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