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  1. NH3Valves

    Safety Relief Valve Testing

    Since I have responded to you before, I assume you are dealing with an Ammonia system where the 5 year replacement rules apply. National Board certified VR shops can test and tag. Some OEMs will recertify their valves. Common practice is replacement, though. Often testing costs nearly as...
  2. NH3Valves

    Relief Line Sizing

    It appears I left out a few important details from my previous post. Po=.15*set pressure + atmospheric pressure P2 is the outlet pressure of the relief piping (usually atmospheric unless relieving to the low side) f=.02 for sch. 40 black pipe L is length Cr is the rated capacity of the valve in...
  3. NH3Valves

    Relief Line Sizing

    For multiple valves at different setpoints discharging to a common header the process for sizing is somewhat complicated. IIAR Piping Handbook (2000) suggests 15% allowable backpressure per ASHRAE 15-2000 as opposed to ASHRAE 15-1994 or earlier that allowed 27.5%. The piping handbook offers...
  4. NH3Valves

    txv pipe assembly

    Parker has a division that does mobile AC assemblies exclusively. Automotive Connectors Division, I believe. They are located in TN. Try www.parker.com/acd. My turn to shamelessly promote.
  5. NH3Valves

    relief valve seat area V disc lift

    To add to what JAlton has stated, while a lift of 25% of the bore diameter creates a curtain area equal to the bore of the valve for top-guided, flat seated, high lift design, I have observed flow limiting curtain areas up to 40% of the bore diameter. This is dependant on the trim geometry and...
  6. NH3Valves

    Ammonia Mass Flow Meter?

    Along the lines of what quark has mentioned, one can obtain information about flowrate from the air or water side of the condenser rather than measuring cooling load. You would need inlet and outlet conditions of both the NH3 and the medium to which it is rejecting heat, as well as, the...
  7. NH3Valves

    Expansion Valve for R410A

    All of the major TEV manufacturers make them for 410A now, I think (Sporlan and Parker for sure). Check their web pages for sizing.
  8. NH3Valves

    Water misters to improve condenser performance?

    ChasBean1 is correct in his statements above, as usual. Adding water to a condenser coil always tends to generate problems with scale, acid, etc... That's why evaporative condensers are not as popular as I feel they should be (too high maintenance). CB's thoughts are accurate and practical...
  9. NH3Valves

    Water misters to improve condenser performance?

    An easier way would be to determine your temperature constraints and limit the water flowrate to keep yourself safe. Check your head pressure on the coolest day you would use the unit. Then wait for a day that is just hot enough for you to want to use the water (90*?) and extremely dry. Play...
  10. NH3Valves

    Water misters to improve condenser performance?

    Sounds like it could work on hot days with some humidity. Essentially adding water mist drops the ambient temperature (dry bulb) seen by the coil to the saturation temperature of the partial pressure of water vapor in the ambient air (wet bulb). If you are in an extremely dry climate this may...
  11. NH3Valves

    Differential Temperature Measurement

    I am looking to measure a differential temperature of about 10 degrees F delta at around 0 F ambient with a reasonable amount of accuracy in a lab environment. I need to do this because I am using a single loop controller incapable of accepting multiple inputs and computing a difference. It...

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