In this episode, Mike and Bob finish the meters series. We discuss what the mindset is from the point that you get a number on your display and the methods and reasons behind what to do.
Complete Show Notes
6:35 Recap of the First Three Metering Episodes
- Basic (or primary) metering technologies – covered how they work and the pros and cons of each technology
- Also covered PID – PID meters read VOC (volatile organic compounds)
- These are substances that contain carbon and hydrogen that is in vapor or gas form (or at least moving in that direction (vaporizing))
- These tend to be toxic compounds that mimic or interfere with our organic chemistry
- Advanced (or secondary) metering technology – covered how they work and the pros and cons of each technology
- Metering techniques – covered how we use meters, when we use them, proper methods of surveying, considerations for use, and how each meter gives us a piece of the bigger picture
10:30 Handling Different Scenarios
- Dealing with inside incidents
- We should talk to people, learn more about the location, ask if the HVAC has been isolated, figure out if there are victims, etc.
- Inside incidents have less airflow and will confine and concentrate chemicals
- You should also be cognizant that the acceptable levels for an inside incident may be different than levels for outside incidents – always check your SOP
- Determine if VOC is a health issue – cleaners, detergents, and household chemicals can all be VOCs
- Low VOC reading – VOC that are toxic and also have low PPM aren’t common in residential areas; a few PPM might not be worth emptying a building
- High VOC reading – the need to protect people increases; many IDLH aren’t this high, but it’s important to consider long-term exposure
- PIDs tend to react quickly – amount of time differs depending on whether you’re using diffusion mode or pump mode (affected by the time it takes for air to move up the tube)
- Meter both high and low – most VOC are heavier than air, but there’s very little stratification between floor and ceiling (focus search on higher levels)
- If you find a source, clean up liquids or stop gas leaks – then, try to vent the area
- Once readings have dropped, stop ventilating and see if VOC returns – if it does, your cleanup wasn’t the issue
- If you can’t find the source, don’t vent unless safety requires it – venting moves air around and can make it difficult to locate the source
- Turning off air handling units may help reduce airflow – if VOC drops after turning off air handlers, it’s getting to the HVAC system somehow
- Ask questions – is there work being done? Cleaning work is a common source, especially if they’re using paint, sealers, polish, etc.
- Is anyone sick? This can include headache, vomiting, dizziness, etc. – do a property history on the patients and request EMS
- Are there smells and odors? Can everyone smell it, or is it limited to a few people?
- Is there a pattern with the odor? Is it a new smell, or something they’ve smelled before and are only reporting now?
- Consider if the source is external – check around the building for unusual items and check the garbage
- Try to map out areas of concentration – can we reoccupy if we couldn’t find anything?
- Dealing with outside incidents
- These can be a concern because the volume of product needed to get a reading outside needs to be substantial
- Wind becomes an issue because it’s difficult to figure out where it came from and where it may be going
- If there are high concentrations, you might need to evacuate people from the area
- Finding and stopping the source of VOC is really the only thing you can do when you’re outside
28:00 Specific Gasses and How to Handle Them
- These readings are taken on 4 or 5 gas meters or single gas meters
- It’s important to have knowledge of the specific chemicals you’re dealing with
- CO
- CO is a product of combustion, so we can narrow our search to combustion objects
- Anything that reacts with O2 to create heat is a concern – burners, ovens, water heaters, fireplaces, grills, etc.
- Once the source is found, turn the item off, vent the space and wait for readings to drop, and stop the vent and see if the reading comes back
- Sulfur dioxide and hydrogen sulfide
- We know these as sewer gasses – they’re products of decomposition and bacteria breaking down waste
- Commonly used in chemical suicides
- Sewers are the most common source – look at plumbing pipes and plumbing traps
- Plumbing traps are a bend in a pipe that traps water – this water prevents the sewer gasses from entering a building – if it’s dry, add water
- Once the source is found and taken care of, shut the vent and see if the product returns
- Sulfur dioxide has been used as a refrigerant, so check old refrigerators and burn up your sensors if there’s high exposure
35:40 How Different Chemical Readings Affect Our Actions
- High O2
- The most likely source is a tank – find the tank and shut it down, then vent and re-check
- Remember that high O2 levels can be dangerous in several ways
- Low O2
- O2 usually leaves areas via displacement – most common reason is a leak of compressed gas or liquefied gas
- Pipe ruptures also lead to leaks – anything that can produce a constant flow of gas for a significant amount of time
- Liquids are rarely able to displace O2 – not impossible, but there needs to be a lot of liquid due to the fact that liquid must evaporate to become a vapor
- Chemical reactions also contribute to low O2 levels – rust, biomass, areas of stagnant air, etc.
- Chlorine
- This is generally an industry gas, but facilities with indoor pools will have chemicals that trigger your chlorine meter
- Typically stored in cylinders
- Ammonia
- Considered to be an industrial gas, but it can really be found everywhere
- Anhydrous ammonia is stored in low pressure tanks in farming areas – it’s also used in cleaning supplies
- Can also be used as a refrigerant – was popular years ago, but is making a comeback because it’s environmentally friendly
- HCN
- This is another common industry chemical that’s used in jewelry businesses and may be present in small manufacturing facilities
- HCN is a product of combustion when dealing with burning plastics and chemicals containing nitrogens
- Radiation
- As long as the source isn’t in the air, this is pretty straightforward
- Always be conscious of time, distance, and shielding
- Chemical warfare
- Many of these meters will alarm for cross-sensitivity
- Figure out if there are any injuries and where the chemical is located
45:25 Other Common Chemicals You Should Meter
- Organophosphates – these are the backbone of many chemical warfare agents and are also the basis of many pesticides and herbicides
- Chances are, you’re getting a false reading, but you should still use the meter to find it
- LEL – find and remove the source; when ventilating, remember that you don’t want to draw a possible flammable through a fan
- It’s always important to know your cross-sensitivities and start by eliminating the chemical your meter is reading for
- Then, use your meter and your understanding of cross-sensitivities to see the big picture
- Always look for CO, acetylene, hydrogen (battery bank or acid metal reaction), too
- THMG014: Metering Overview and Basic Sensors
- THMG016: Metering Techniques and Reading the Numbers
- THMG015: Advanced Metering
Have a question? Send an email to feedback@thehazmatguys.com or leave a message on our Haz Mat Guys comment hotline: 843-628-1484