PEX for higher pressures

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Wet_Boots, May 12, 2007.

  1. Wet_Boots

    Wet_Boots Sprinkler Guy

    Joined:
    Mar 23, 2007
    Location:
    Metro NYC
    What pressure ratings are available for PEX, if considered for usage at higher pressures, in instances where pressure regulation won't be workable? I don't think the 160 psi ratings I see will provide enough of a safety margin. Do they have standards for thicker-walled tubing than SDR-9?
     
  2. kordts

    kordts In the Trades

    Joined:
    Oct 15, 2005
    Occupation:
    industrial service plumbing foreman
    Location:
    exurban Chicago
    Call the manufacturer or supply house. 80 psi is the highest allowable domestic pressure. Industrial or commercial is usually speced by an engineer or architect.
     
  3. Sponsor

    Sponsor Paid Advertisement

     
  4. Wet_Boots

    Wet_Boots Sprinkler Guy

    Joined:
    Mar 23, 2007
    Location:
    Metro NYC
    80 psi would be about as much as I'd want to expose a 160-psi-rated tubing to, although Zurn, for one example, suggests a 50-percent pressure margin.

    This inquiry is for a few homeowners who have thoughts of adding secondary water meters to feed existing lawn sprinkler systems, and are looking at long runs of copper, some of them in finished basements. Since the systems are using every last psi of water, there isn't an opportunity to reduce the supply pressure to a safe 80 psi.
     
  5. kordts

    kordts In the Trades

    Joined:
    Oct 15, 2005
    Occupation:
    industrial service plumbing foreman
    Location:
    exurban Chicago
    80 psi is way plenty for lawn irrigation systems. If the system is designed and installed properly tha's all it needs. If the system was designed figuring on pressure over 80 psi, then the designer was a moron. 80 psi is code all over the US. I have installed lots of RPZ's for lawn irrigation systems where it was 50 psi. If you are a licensed plumber, and you know the pressure is over 80, you better reccomend a PRV, if they don't want one, walk away. The lawyers will come after you if anything bad happens. Helping somebody do something against code is a lose-lose.
     
  6. hj

    hj Master Plumber

    Joined:
    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    Pex

    The pressure rating for PEX goes down as the temperature goes up, so you have to know the ambient temperature of the area before you can decide whether it is adequate or not.
     
  7. Wet_Boots

    Wet_Boots Sprinkler Guy

    Joined:
    Mar 23, 2007
    Location:
    Metro NYC
    In the sprinkler system itself, I fully agree. But the static supply pressures often go beyond 100 psi.
    Designers tend to use what they have, and watering restrictions can require them to get the sprinkling done within a certain time frame, so nobody likes to leave any potential flow unused. That's what makes cutting in a PRV a no-go, since the system reworking could involve time and material exceeding the cost of doing the new supply work in copper
    I also do RPZ retrofitting, and often have to inform a homeowner that they have inadequate, or non-existent, backflow protection, and that I won't be able to do any repairs unless the backflow protection is brought up to code. RPZ retrofits can cost more than a homeowner with one broken sprinkler head is willing to pay.
    There are too many thousands of houses without PRVs, with pressures beyond 100 psi, for me to believe that authorities around here consider it a public safety hazard. It's bad enough when someone signs off on a home inspection where the backflow protection is missing. (they seem to spend most of their time looking for sump pumps draining into the sewer system - those they catch)

    My searching for higher-pressure PEX didn't turn up any specific examples yet, but I think there are some out there, according to an NSF approvals page. Funny thing, is that there is now a higher-pressure form of the 'ordinary' polyethylene tubing, made from a new resin. Unfortunately, nearly every mention of polyethylene tubing states that it is not intended for indoor usage.
     
  8. kordts

    kordts In the Trades

    Joined:
    Oct 15, 2005
    Occupation:
    industrial service plumbing foreman
    Location:
    exurban Chicago
    It ain't the authorities, it's the lawyers you gotta worry about.
     
  9. hj

    hj Master Plumber

    Joined:
    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    Pex

    If PEX came with a thicker wall, then it would have to have an entirely differenent line of fittings because the internal diameter would be smaller than conventional PEX and the fittings would not be insertable.
     
  10. Bob NH

    Bob NH In the Trades

    Joined:
    Oct 20, 2005
    Location:
    New Hampshire
    The specified pressure rating of pipe is the working pressure. The burst pressure is usually 3 to 5 times the working pressure.

    If your water system operates above 160 psi then you are wasting energy. The only application for higher than 160 psi is with wells that are very far down to the water level, or if you have a submersible pump with some kind of throttling or control valve between the pump and the pressure tank.
     
  11. Wet_Boots

    Wet_Boots Sprinkler Guy

    Joined:
    Mar 23, 2007
    Location:
    Metro NYC
    Of course, on a sprinkler system with diaphragm zone valves, there is a distinct possibility of water hammer, and the pressure spikes that go with it. I suppose the PEX has expansion capabilities to dampen the effect, but it's another concern that makes me unwilling to overstep any manufacturer's safety margins.
     
Similar Threads: higher pressures
Forum Title Date
Plumbing Forum, Professional & DIY Advice Drain Pipe is higher than sink. Any thoughts? Oct 5, 2020
Plumbing Forum, Professional & DIY Advice Why does my house water pressure rise higher than the regulator setting May 1, 2020
Plumbing Forum, Professional & DIY Advice Delta Shower Valve won't go higher than 80 degrees Dec 15, 2019
Plumbing Forum, Professional & DIY Advice First post: waste arm higher than drain Nov 18, 2019
Plumbing Forum, Professional & DIY Advice New sink drain higher Feb 25, 2019

Share This Page