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  • Users: sterl
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  1. sterl

    Mechanical Room Layout Resources

    Confucius say: Look at what it takes to work on it....Buick may a car in the 1970's that had to have the engine lifted to change the spark plugs (actually only 2 of them). So find out what pieces in your industry require renewal or other maintenance input from time to time; read up on the...
  2. sterl

    water hammer valve opening

    If you are making up liquid to a saturated vessel with a cycling valve you have a 2-phase topic...and likely condensation induced shock. Is the upstream pipe colder than its surroundings and higher than the source liquid level? Is the immediate downstream above or below the operating liquid...
  3. sterl

    Experience with H2S

    HSE is simply Health, Safety, Environmental. H2S is highly corrosive and reactive; and on exposure to air makes H2SO4 which is sulphuric acid. Sulphuric acid and any of a variety of metals make a battery. Corrosion plus water flow make nasty sediments. Finned coils turn into shallow mounds...
  4. sterl

    Condensation and Freezing in a Duct

    Actually blizzard would be pretty close. Unless that 18-deg Air Stream is at less than about 8% Rel Humidity, this mix is going to be saturated or supersaturated and the outbound temperature is going to be higher than the pure mixed enthalpy numbers would indicate due to the latent of the...
  5. sterl

    heat exchanger pressure drop

    Unless this a very strange form of tube, your pressure drop is entirely dynamic but... The tube being same size end to end and same flow in as out: A PG on the entry side is connected to the tube and in the same fashion and orientation as other PG is connected on the outlet, the dynamic...
  6. sterl

    tr for ammonia

    Evaporative Condenser? Or Water Cooled? Evaporative, forced draft: at best you can estimate for "fully known" operating condiiton: That is run all the fans fulll speed, measure air dry bulb and wet bulb in and out, look up enthalpy change on a psychometric chart. Once you have heat, take out...
  7. sterl

    Cavitation on suction side downstream from cooling towers

    Air entrainment much more likely than saturation basis of NPSHR if this a ordinary cooling tower installation. If you have something on suction side that represents a big restriction, air could be finding point of entry other than sump pipe stub.. Other than that: Lower and widen the pipe...
  8. sterl

    Choked Flow vs. Critical Flow

    Choke refers to the device: An orifice can be considered Choked if a reduction in downstream pressure will not increase flow. Critical refers to the fluid pressures (usually ratio) at the point at which the device becomes "choked"...For gases, the consequence of critical pressure difference...
  9. sterl

    Solenoid Tube Burn Through

    That's a Refrigerating Specialties solenoid in all likelihood; and in a freeze-thaw environment, its very likely that it is shorting to the tube because the slight annular space between tube and innner bore is retaining some water while the coil is energized, which freezes when the coil is...
  10. sterl

    Evaporator coil tubes collapsing in large freezer

    Seen this quite a few times...On DX coils and particularly where there is residual lubricant in the evaporator during defrost. Refrigerant evaporates, lube left behind, drainage from upper tube & fins hits cold oil and air near bottom, part of it wraps around bottom tubes, forms its own hard...
  11. sterl

    Expansion Tank for GSHP, is this necessary

    If your in-ground grid is going to be operating at fluid temp of minus 5 C. occasionally and you are thinking the PEX is going to expand: Consider that some of it will at least short term be surrounded by frozen ground; and that its always going to have to push ground around in order to expand...
  12. sterl

    low temp screw compressors

    How the machines lubricated and cooled? Are they slide valve machines or does their capacity reduction take another form? Do they have external lubricant cooling or?? Are they hermetics, semi hermetics or open drives? If they are hermetics or semi hermetics, measuring their real performance...
  13. sterl

    Removing heat from wastewater flow

    I believe you are trying to upgrade the available heat or is the real objective to cool the drain water??? If its the evaporator side of a heat pump, the target temperature of the heated fluid determines what your compression arrangement will look like; lots of reasonably inexpensive pieces...
  14. sterl

    Shell and Tube Heat Exchanger Tube Failure

    What else is consuming steam from your circuit? As banged up as these tubes are over a considerable extent: Something has got to be dropping the steam pressure, which causes the condensate to lift as it tries to re-establish saturation; and in worst cases your heat exchanger starts generating...
  15. sterl

    Laundry equipment heat gains

    This a Big Commercial or maybe a Hospital Laundry? If its of any scale, its an air handler exercise. If its a Local Coin Op: Triple the normal for the Sq Ft of space, like it was a retail store....And take controll of the drier intakes. And the chemistry can be fun even then... Most of the...
  16. sterl

    Heat Pumps In general

    Heat is transferred from the refrigerant to the surrounding (Nominally air if this is a Comfort Heater) on the high pressure side of the system by the heat exchanger called "condenser"...The refrigerant is thus condensed. Heat is transferred from a different set of surroundings (in this case...
  17. sterl

    Pumps in Parallel Project

    Somebody got close to saying it but.... Drives need to match system requirements; and controls need parallel system responses. A high differential pump required because the system has a high static head or contains spring loaded in line components or even thermal control type devices do not...
  18. sterl

    Compressor building requirement

    This machine room freestanding or surrounded by a process building? Process involve chemical vapors or similar? Breweries do exactly this so they don't end up filling CmA instrument lines with "byproduct" and crudding them in a few weeks; positive pressure simply keeps the stuff from...
  19. sterl

    Components of kW/Ton

    I believe the key to your question is the units: They are really KW-Hr per TR-Hour. The only way you can get to TR-Hr is to detail-model the duty cycle. Lots of them have been done for Air Conditioning type operating conditions and "normal" occupancy; Carrier has "bin-method" software that...
  20. sterl

    Cooling Load Calculation

    Presuming there is some control on the process, its very likely that the entire extent of the coil, side to die adn through and through, is at 400 Deg. when it enters the shed... But if its shaped and reconditioned by machines and tools it is not going to be 400-deg, and neither is it going to...

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