1. Vitaliy

    Vitaliy New Member

    Messages:
    73
    Location:
    Massachusetts
    Hi,

    Can I put together two fittings if one is NPT and another one is NPS
    or this must not be done under any circumstances?

    Thank you,

    - Vitaliy
  2. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    What is the application? They will screw together, usually loose; but will not make a seal. A typical situation would be the straight threads on faucet inlet; a female tapered adapter will not seal well, but enough teflon sometimes makes it OK!
  3. Vitaliy

    Vitaliy New Member

    Messages:
    73
    Location:
    Massachusetts
    Hi Jimbo,

    Yes, you made a point!
    I bought that Ez-Faucet toy. (BTW so far it works OK)
    HJ made a very good point about potential cross connection problem.
    I don’t like to introduce problems. The solution is to install check valves.
    Unfortunately I did not find any 3/8†check valves but I found this things:
    http://www.camco.net/Menu.cfm?SupCategoryId=10000&SubCategoryId=214&ProductId=2078
    Everything looked OK except for the faucet inlet has straight threads but
    the above check valves are tapered. Looks like I should not even try
    to install them.

    - Vitaliy

    By any chance does anybody know where to buy correct check valves?
    Please, post a link.
  4. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    With the right adapters you could connect the check valves in between two flexible faucet connector lines.

    I estimate you could pay for about 23000 gallons of water with what you have spent on this, but if it makes the wife happy, it's worth every dime!
  5. Vitaliy

    Vitaliy New Member

    Messages:
    73
    Location:
    Massachusetts
    Adaptors and happy wife.

    Hi Jimbo,

    So, could you please advice what adaptors to use or which
    check valves to buy and WHERE??? to buy them (for some reason
    I cannot find these things at all, i.e. place where to buy)?

    Thank you,

    - Vitaliy

    PS.
    23000 gallons will cost me about $250
    So far I spent only about $70 which is about 6500 gallons.
    But you are absolutely right – happy wife is a key point!
  6. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Let's assume you have a 3/8 compression outlet from your angle stop. A 12" long faucet connector ( 3/8 compr. X 1/2 IPS ) will connect from the stop valve to the input of the check valve. Now, 1/2 IPS close nipple inserted into the outlet of the check valve, and another faucet flex, 12" long, (1/2 IPS X 1/2 IPS) will connect from the nipple up to the faucet. All of these connections are "normal" and very reliable.

    Note that the 1/2 IPS ends of the faucet flex connectors are straight threaded nuts, used only for mechanical strength. The rubber gasket makes the seal.
  7. Vitaliy

    Vitaliy New Member

    Messages:
    73
    Location:
    Massachusetts
    Confused?

    Hi Jimbo,

    Your assumption is correct but now I am confused.
    OK, valve outlet is a 1/2 FIP.
    If I can screw in 1/2 IPS close nipple then why I cannot screw it right on
    faucet inlet which is also 1/2 IPS? Combination of 1/2 IPS x 1/2 IPS flex
    with 1/2 IPS close nipple looks like faucet inlet extension. Is not it?
    And looks like connecting 1/2 IPS flex to the 1/2 MIP valve inlet is also
    not a problem.

    HJ and Terry warn me not to go this way.
    What I am missing here?

    Thank you,

    - Vitaliy
  8. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Well, if I read the arrows correctly, that would be backwards, but more important the outlet from the valve is that straight thread we have been talking about. It is meant to have a nut-connection with rubber gasket seal. Your taper-thread fitting would screw on bu probably leak.
  9. Vitaliy

    Vitaliy New Member

    Messages:
    73
    Location:
    Massachusetts
    Threads compatibility?

    Hi Jimbo,

    OK, forget about that valve.
    I really would like to understand threading compatibility issue.
    It is clear that NPS-to-NPS is OK with gasket seal and NPT-to-NPT
    is OK with Teflon Tape and/or Teflon Dope (or both) seal.
    But how about NPS-to-NPT, M-F combinations?
    Which combination is OK and which one is not?
    A link to the site with good explanation is fine.
    Looks like IPS-to-MIP with gasket seal is OK. Yes, no?

    Thank you,

    - Vitaliy
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,251
    Location:
    Cave Creek, Arizona
    connection

    NPS always has to have a gasket of some kind because there is no way to make the threads seal.

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