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  1. mysterylectricity

    Small compressor maximum case temps rule of thumb?

    Hi, As a rule of thumb, what are maximum case temperatures of small compressors? Stat cooled in particular. Is it worthwhile to make a distinction between the "average" temperature of the housing and the peak temperatures of the housing immediately adjacent to the HP line? My reasons for...
  2. mysterylectricity

    Any refrgerants "left" for the experimentor?

    Hi, Are the sales of _all_ refrigerants in the US restricted, or only the eco-nasty ones? At least as of a couple years ago, most industrial supply catalogs made it clear that the sale of CFC's and HFC's(?) were restricted, but the implication was that the sale of other refrigerants was not...
  3. mysterylectricity

    -80¦C refrigeration, single stage in -20¦C ambient?

    Hi, If you don't need much lift, look into the technology used by Labconco, Titan, and other companies in their single-stage freeze driers. I _think_ the new ones are rated as low as -80 single stage, at 32C ambient. I'm looking into this myself, so let me know if you find anything. My older...
  4. mysterylectricity

    "Single-Line" coldfinger evaporator connection?

    Hi, I have a "coldfinger" unit consisting of a compressor joined to a flatish-tube spiral coldfinger by a flexible line. What's a bit strange to me is that in this unit and in similar units I've seen, it appears as if there is a single line to the coldfinger. I've considered the possibility...
  5. mysterylectricity

    Now how about -60C single stage from approx. 35C

    Hi, Anyone know off hand the complement of components used in modern single-stage freeze dryer and vacuum trap type units? What is the preferred refrigerant and oil complement? Are "special" compressors needed? I have older units that achieve -60C quite easily air-cooled at "room" temperatures...
  6. mysterylectricity

    -80¦C refrigeration, single stage in -20¦C ambient?

    I don't think those cryocoolers use a mix of exotic refrigerants, they use medium-pressure helium (~300 psi) always in the gas phase. This is rapidly compressed and relaxed (60 hz) with about a %25 pressure swing. Some designs use a moving part in the cold head, but some don't (pulse tubes)...
  7. mysterylectricity

    Is a ground rod needed for industrial machinery?

    Is the equipment grounding conductor in the raceway sufficient to bond the proposed additonal grounding rod into the grounding system as a whole? What is the requirement?

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