pressure relief for paint can load?

Discussion in 'Amateur Radio Amplifiers' started by W1BR, Feb 2, 2018.

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  1. WA7PRC

    WA7PRC Ham Member QRZ Page

    My HN-31 Cantenna has a "pop off" pressure relief valve:
    [​IMG][​IMG]
    After I refurbished it and refilled with new and FREE transformer oil, it has never "weeped" (I use my air-cooled 1600W dummy load). So far, I've not had a problem with it spilling air. ;)
     
  2. K6BRN

    K6BRN XML Subscriber QRZ Page

    The oil provided with the MFJ cantenna is simple mineral oil and vaporizes at room temperature. Best of luck with your free PCBs.
     
  3. W1BR

    W1BR Ham Member QRZ Page

    In retrospect, the oil filled Waters loads have no relief mechanism.. The sealed reservoir must have a lot of air to allow for expansion? Mine developed a solder seam leak and Waters replaced the load assembly to fix it. I have a TenTec 240KW forced air cooled load in addition to the Water 334A, but I want to do something useful with the Waters load resistor assembly that was returned along with the repaired wattmeter.

    Before any TenTec fans ask, the 24oKW exists, but it was never sold in great quantities and is quite rare. Force air cooled and 1500 watts with derated limited operating times.
     
  4. K1TGX

    K1TGX Premium Subscriber QRZ Page

    It was just an example :)
    If you limit temp to 240 deg F you will get 75% of the expansion (I would never let it go any hotter than this)
     
  5. KP4SX

    KP4SX XML Subscriber QRZ Page

    No, the little plastic relief valve.
     
    W1BR likes this.
  6. W1BR

    W1BR Ham Member QRZ Page

    Oh the last line ditch of protection before my DL turns into a bomb:) Not sure what the PSI is, where to find one--are they expendables like the seals? Next question is how long before the lid pops off the can?

    Off the shelf pressure cookers seem to max at 15 PSI, the safety must be higher.
     
    Last edited: Feb 3, 2018
  7. KP4SX

    KP4SX XML Subscriber QRZ Page

    They sell them at the grocery store here. Some are one-shot wonders. Lots of them showing on ebay :)
     
  8. W1BR

    W1BR Ham Member QRZ Page

    I'll take a look!
     
  9. KD2ACO

    KD2ACO Platinum Subscriber Platinum Subscriber Life Member QRZ Page

    I'd be afraid to trust a paint can of hot oil much above ambient pressure.
     
    Last edited: Feb 3, 2018
  10. K1TGX

    K1TGX Premium Subscriber QRZ Page

    There's another good idea. . .
    Tap the top with that 3/8 od tubing and bring it to an open expansion tank (like the earliest hot water heating systems worked). The 'tank could be that 3" piece of copper tubing standing vertical above the DL. No pressure then
     

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