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Recent content by m2e

  1. m2e

    Sewage Lift Station Blower Heater - Class 1 Div 1

    A sewage lift station is being designed for a residential area, so an odour control unit is required to maintain the below-grade chamber in a negative pressure. A blower-heater unit sits on top the wet well to provide tempered make-up air so the liquid won't freeze. The unit we're using is this...
  2. m2e

    Aluminum damper in galvanized duct - dissimilar metal corrosion?

    If you put an aluminum control damper (such as Tamco or similar) in a section of galvanized steel duct, would galvanic corrosion be a concern? Similarly, if you have an aluminum intake or exhaust louver connected to galvanized ductwork, would that be a concern too?
  3. m2e

    Outdoor make-up air duct insulation

    It's correct about the hypothetical RH%. We should remove the indoor RH as a known too then: 1. Room in cold and dry climate Outdoor air: -40 C, 100% RH Indoor air: 18 C (electric heat and DX cooling) Duct: 500mm x 500mm, 5 m long, 200 L/s, -40 C supply air 2. Room in warm and wet climate...
  4. m2e

    Outdoor make-up air duct insulation

    The details are missing on purpose because as mentioned it's a conceptual question. Intuitively it's easy to understand you'll have condensation in rainforest but not in the desert. I'm looking for a generalized methodology and equations to evaluate the problem and calculate the required...
  5. m2e

    Outdoor make-up air duct insulation

    I have a conceptual question to aid my understanding of thermal insulation and duct condensations. Suppose there is an equipment room that needs a small amount of make-up air for pressurization. There is a supply fan that takes air from an intake louver, through a supply duct, and delivers it...
  6. m2e

    Evaporation rate and ventilation calculation

    Thanks for the responses. Sorry I have missed the notifications for the replies. The question is regarding a generic chemical storage room where the chemicals are stored. Alternatively, the situation could be that the chemicals are also stored in the pump/piping room where the chemicals are also...
  7. m2e

    Evaporation rate and ventilation calculation

    For a chemical storage room, let's say you have a tank of chemical for a certain process, for example chlorine or fluoride for water treatment processes. How do you calculate the evaporation rate of such chemical, and how much ventilation is required to remove the vapor in order to meet OSHA or...
  8. m2e

    NFPA 820 Wet Well Ventilation - Dry Volume or Air Space Above Liquid?

    There is a fairly large wet well that I will need to ventilate per NFPA 820, 12 ACH to classify it as class 1 div 2. We also need to provide odour control to the exhaust air, so that resulted in a huge odour control unit. NFPA 820 stated 12 ACH is required, but can we get away with only...
  9. m2e

    Snow melt thru a panel

    I am not at the liberty to disclose any drawings, but ground snow is not a problem because the antennas are well above the snow level. The ice that are causing problems is rime ice.
  10. m2e

    Snow melt thru a panel

    Yes, blower heater is a possibility, but first I'll need to size the heater.
  11. m2e

    Snow melt thru a panel

    Yes, at lease as little ice as possible
  12. m2e

    Snow melt thru a panel

    It's a telecom enclosure. Some antennas are housed inside and the ice on the walls blocks the signal.
  13. m2e

    Snow melt thru a panel

    "For an enclosure, that requirement is unnecessary, and any buildup is apparently acceptable so long as there's no ice in direct contact. That could allow for power densities down in the 0.25 W/in^2 or lower." Could you elaborate a bit on this? How would buildup affect the power densities? How...
  14. m2e

    Snow melt thru a panel

    Somehow I wasn't getting the notification emails so I've missed a few messages. It's a telecom type building and the ice buildup is blocking the RF signal. Heat tracing doesn't work because it'll block the signal too.
  15. m2e

    Snow melt thru a panel

    Thanks for providing this. Using the table and chart, assuming the lowest number, 2.5 W/in^2, for a 10ft x 10ft panel, the power required is 36 kW. This seems to be excessive. Perhaps the tables are for high altitude, high speed, and cold ambient temperature? Is there any way to calculate the...
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