Home Podcasts THMG057 – 29 CFR OSHA PPE Selection, Part II

THMG057 – 29 CFR OSHA PPE Selection, Part II


In this episode, we continue discussing PPE and begin talking about different kinds of SCBA.

Complete Show Notes

1:30 Level A

  • Involves a vapor/gas-tight protective garment, full-body coverage, and SCBA or SABA with a pony bottle
  • Provides maximum skin, mucous, and respiratory protection
  • Divided into multiple types
    • Type 1
      • Designed to cover the user completely and protect the airway completely
      • SCBA is worn inside the suit
      • These are gas-tight, which means they only vent through one-way ports and have vapor-tight zippers
    • Type 2
      • This is a hooded-type garment and SCBA is worn on the outside
      • This means you need a chemical-tight seal on the hood via a connection between the SCBA facepiece and the hood gasket
      • Type 2 suits have vapor-tight zippers, seams, and gaskets
      • Typically worn when movement is a limiting factor – like confined spaces
      • However, they take longer to take on and off, and because your respiratory protection is exposed, it’s harder to decon
      • OSHA 29 CFR 1910.120 doesn’t recognize Type 2 as part of Level A because it’s not “fully encapsulating” – however, if you’re going into a tight space and need Level A protection, you’ve got to go with Type 2
    • Type 3
      • Designed for use with SABA and an escape cylinder
      • Respiratory protection can be worn either inside or outside the garment
      • If we use SABA on the inside, we need a bulkhead or “pass through,” which is a fitting that allows the air hose to connect through the suit

    11:00 Airway Protection Testing Requirements

    • We use 3 different types of protection: APR, SCBA, and SABA
    • 20 CFR 1910.134 describes two different types of fit tests – qualitative and quantitative
    • Qualitative fit test
      • Involves an odorant (i.e. saccharin or amyl nitrate) – if the user can smell it, you’ve got a fit problem
      • Qualitative method is described in more detail in 29 CFR 1910.1001 Appendix C (asbestos), 29 CFR 1910.1025 Appendix D (lead), and 29 CFR 1910.1028 (benzene)
    • Quantitative fit test
      • This is the method the majority of us use
      • Use instrumentation to check the amount of air that leaks out – this helps us figure out the protection factor for that method of respiratory protection
      • Procedure for this method of testing depends on the equipment used
      • ANSI Z88.2 – 1980 describes a typical test protocol and exercises for the quantitative method

    14:00 Air Purifying Respirators (APRs)

    • Selectively remove contaminations via four different methods:
      • Filtration
      • Absorption
      • Adsorption
      • Chemical reaction
    • Cartridges used for contaminant removal are specific to the product or at least to the chemical group
    • Remember that APRs are negative pressure devices
    • 29 CFR 1910.134 requires a standardized color code for APR cartridges
      • Purple stripe for radioactive materials in combination with any vapor or gas
      • Orange stripe for dusts, fumes, and mists in combination with any vapor or gas
    • Check your cartridges to see what they’re compatible with and for more information
    • APRs offer less protection than SCBA – we measure this based on the protection factor
    • Taking the protection factor and multiplying it by the PEL gives us the upper limit of capability for an APR – this is assuming that we haven’t exceeded the IDLH concentration
    • Protection factors:
      • Half-face APR: 10
      • Full-face APR: 50
      • PAPR: 100
      • SCBA/SABA: 10,000
    • Remember that APR has no end-of-life signal, which is indicated by breakthrough – when this happens, the contaminant we’re trying to keep out is now coming in
    • Cartridges may become full of dirt, mucous, chemicals, etc., which makes breathing increasingly more difficult
    • However, there are several contraindications:
      • Atmospheres that are IDLH
      • Atmospheres that are oxygen deficient or enriched
      • Dealing with unknown products
      • Concentration of product that exceeds the capabilities of the cartridge
      • Products that pose a health risk or are below the odor and taste thresholds
      • High moisture
    • If we have a product that’s known to have a poor warning property, we have to reconsider
    • It’s also important to be concerned about chemicals that have no end-of-life warning other than load up or breakthrough
    • One exception to this is benzene (a known carcinogen) – when we’re working with this substance, we have to change the filters daily, regardless of their status

22:50 Breathing Apparatuses

  • Device that lets us take the normal air we breathe outside and use it in a hazmat zone
  • We use this with SABA, which is tethered to the cylinders via a hose
  • Dual-Purpose Breathing Apparatus (DPBA)
    • Units with applications in limited access or extended use situations
    • All of these apparatuses (SCBA, SABA, DPBA) have a protection factor of 10,000, which is the best we can get
    • Note that SABA may not have a low-pressure alarm built-in, and some don’t even have a PASS alarm signaling that the user has been motionless – look into yours to learn what its capabilities are

25:00 Closed- and Open-Circuit Systems

  • Open circuit
    • In these units, we exhale into the surrounding atmosphere – this is what we typically use
    • They’re usually a bit heavier than closed-circuit units
    • You fill the suit with depleted air with a concentration of oxygen that you can’t breathe, but we’re really comfortable in them
  • Closed circuit
    • In these units, we recycle the air we exhale, freshen it up, and re-breathe it
    • These usually give us more working time, but you have to deal with hot and overly moist air coming back to you
    • Also bringing a bunch of pure oxygen into the area, which could be bad if something malfunctions
  • Cryogenic breathing systems are also coming out – these liquefy air and put it into a cryo tank (this means it’s low pressure)

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