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Dental Air Compressor Types

  • Wednesday, December 09, 2020 4:58 PM
    Message # 9417971

    NFPA 99 (2018) says that "Air compressors shall be scroll dental, reciprocating
    dental, or the oil-free dental types." Would oil lubricated (oil flooded crankcase) dental type of reciprocating compressors be acceptable, or should they be restricted to oil-less (sealed bearing) types?

  • Thursday, December 10, 2020 5:11 AM
    Reply # 9419047 on 9417971

    They must be Oil Free type dental air compressors, meaning no oil anywhere.

  • Thursday, December 10, 2020 6:22 AM
    Reply # 9419114 on 9417971
    Al Moon (Administrator)

    Please review ( To the best of my knowledge / oil free compressors still have oil in the crank case / but has protection against migration of the oil up to the compression chamber ) but ( Oilless has no oil at all ).


    Google / Ingersoll Rand Type 30 Systems 

  • Thursday, December 10, 2020 12:53 PM
    Reply # 9419981 on 9417971

    I don't think there is a good answer to your question relating to Dental air but there is a good answer relating to Medical Air which I would reference to your concern of hydrocarbons getting into the pipeline. 


    If 2021 edition 5.1.3.6.3.4 (A) (2) and (3) are met relating to Compressors for Medical Air are met than, I would argue that 5.1.3.6.3.12 (E) (2) and (4) should be followed. 


    5.1.3.6.3.12 Operating Alarms and Local Signals. Medical air
    systems shall be monitored for conditions that can affect air
    quality during use or in the event of failure, based on the type
    of compressor(s) used in the system.

    (E) Where compressors compliant with 5.1.3.6.3.4(A) (2) and
    5.1.3.6.3.4(A) (3) are used, the following requirements shall
    apply:

    (2) Coalescing filters with element change indicator shall be
    provided.

    (4) Gaseous hydrocarbons shall be monitored on a quarterly
    basis.

    The reason I would argue this is because the concerns mentioned of dental air should not exceed the same concerns of Medical Air in my opinion. We should agree that Medical Air needs to be the higher standard in this case. If we are meeting a higher standard, than it is acceptable under these conditions.


    Merry Christmas everybody!!


  • Friday, December 11, 2020 7:38 AM
    Reply # 9421968 on 9417971
    Al Moon (Administrator)

    In older editions of NFPA 99.

    The clarity of the Category 3 / Section Gas-Powered Device Supply Systems ( compressed air and nitrogen ), is not as well defined, as it is today in the newer NFPA 2018 Edition Chapter # 15.


    But Section #15.3.3.4.2 NFPA 99 - 2018 Edition / Dental Air Compressor Units, makes it totally clear. The air compressors SHALL BE scroll dental, reciprocating dental or the oil-free dental types.


    My understanding still is: 


    OIL-LESS =  No Oil At All 


    &


    OIL-FREE = THERE IS OIL IN THE GEARBOX -BUT IT DOES NOT COME INTO CONTACT WITH THE COMPRESSOR (i.e. compression)


    Dental Air Is A Support Gas, Not A Respiratory Medical Gas.


    As a whole its used to power equipment and for the clinician hand piece blow tool (i.e. to blow out and dry out the mouth).

    But not used as the medical air life supply respiratory gas air system.

       




  • Monday, December 14, 2020 9:58 AM
    Reply # 9428699 on 9417971

    Most interesting discussion!   Reminiscent of the arguments back in the day around what compressors should be permitted for medical air!


    Al is right - oil free means "no oil in the product air", but not "no oil in the compressor".  So, in code terms (2021 99)

    5.1.3.6.4 (A) (1) compressors: Oil less (sealed bearings) {scroll, oil less reciprocating}; 

    5.1.3.6.4 (A) (2) compressors: Oil free reciprocating (oil in gearend but not in airend) {T-30 ish, but the T-30 itself doesn't cut it} 

    5.1.3.6.4 (A) (3) compressors: screw/tooth compressors (oil in gearend but not in airend) {Z compressors, oil free screws}

    5.1.3.6.4 (B) compressors: liquid ring.


    To me, the dental rule as written would appear to allow any of the first three. 


    I disagree slightly on the cleanliness requirement - I think dental air may be slightly more critical because as I understand it a tiny amount of oil will interfere with the bonding process, so oil free air means a very great deal to the dentist from a practical viewpoint. Maybe Dan Shoemaker can weigh in?  

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