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  1. PS

    How much pressure is required by an exhaust fan when it exhausts straight up?

    Hi.. Density change in air with 30 feet height is insignificant and change in pressure due to this 30 feet altitude is also insignificant. You can ignore it in case of air. Just calculate the duct+fittings losses and safety margin of 15% and proceed further.
  2. PS

    Hospital Air-conditioning - Oncology Department

    Dear All, I'm a consultant engineer and need to design a hospital that treats cancer patients with nuclear medicine. Here is a situation, I'm air-conditioning a LINAC Bunker rooms with once thru system. I've done all calculations and other heat load related stuff. Now the concern is about the...
  3. PS

    Dehumidified CFM by Sensible and Latent Heat- HVAC

    Why are we calculating dehumidified cfm using sensible heat alone? Will the cfm be different when calculated using latent heat? And why coils are selected based only on inlet and outlet temperatures but NOT in relevance to humidity ratios? Why in design for comfort applications we always say...
  4. PS

    VRV vs DX Inverter Life Cycle Cost Analysis

    Hello everyone, I'm doing a comparison between DX inverter model machines and VRV/VRF sytem. I'm comparing in all terms, CapEx, OpEx, system performance, ease of operation, etc. I'm in need of data like ikW/TR for DX inverter and VRF systems. Further to that, is it a good idea to compare the...
  5. PS

    Selection of Air Handling Unit (Chilled Water Type)

    thank you @GT-EGR and @moideen.
  6. PS

    Selection of Air Handling Unit (Chilled Water Type)

    Thank you GT-EGR. "So if your 9,000 CFM x conversion factor x (space temp - air temp) = your sensible load, then your air handler is selected correctly." Am I suppose to take only the sensible load and proceed with the AHU selection? I get struck everytime in this place. The AHU catalog does...
  7. PS

    Selection of Air Handling Unit (Chilled Water Type)

    Hello All, I have a situation where the result of heat load, which was done by a consultant, is 9000 CFM at 20 TR. The heat load summary is given below: Sensible Heat Gain: 63 kW Total Heat Gain: 70 kW (20 TR) Dehumidified Air Quantity: 4250 L/s (9000 CFM) Inside Design Conditions: 23+/-1 degC...
  8. PS

    Selection of Equipment: Tonnage Vs CFM

    Thanks a lot @lukaiENG. The concern is I need to use the 4 TR units accordingly to suffice my heat load. No other go for me. That is troubling my calculations. I also tried to match the off coil temperature of the units as my supply temperature but I'm ending up nowhere in that case. Thanks...
  9. PS

    Selection of Equipment: Tonnage Vs CFM

    Hello Professionals, According to heat load calculations, I'm getting 80 TR and 32800 dehumidified CFM for a subjected space, a shopping complex. The situation is I need to use only 4 TR cassette split units for the space. The cassette units are rated for 4 TR at 1140 CFM. Now should I go for...
  10. PS

    Clarifications on Manual Heat Load Calculation

    Hello All, I just want to be certain on a few things while doing heat load calculation. Please do advise. 1. What is the significance of using "COOLING/HEATING DESIGN DAY and DESIGN MONTH conditions" over the "OCCURRENCE PERCENTAGE conditions" while selecting the outdoor weather data? Is the...
  11. PS

    Meeting with Architect

    Hi All, I'm having a meeting with architect to get inputs for our machining workshop air-conditioning project. I have a few points noted, but still I want to be confident during the meet. Would you please suggest few points and checklists that I need to ask him?
  12. PS

    Shades for EXTERIOR WALLS in HAP

    Thanks a lot! @dbill74.
  13. PS

    Shades for EXTERIOR WALLS in HAP

    Hello Professionals, I'm in need to calculate the cooling load of a portable container (18m x 7m) that is placed inside a completely shaded area. That is the container is placed inside a workshop. The workshop is roofed with corrugated metal sheet (w/o any insulation). Now, using HAP, I need to...
  14. PS

    Insulation Thickness Calculation

    Thanks all, esp @PEDARRIN2. Those links were really awesome!! And regarding ASHRAE 90.1, it is clearly mentioned that the calculation of thickness is based on energy efficiency. So, I tried calculating the required thickness of insulation that is sufficient to avoid condensation. I followed...
  15. PS

    Insulation Thickness Calculation

    Hello Engineers, I need to calculate the insulation thickness needed for CHW pipes and ducts. The operating range of temperature in pipes is 6 to 12 deg C and of ducts is air at 14 deg C. No return air ducts used in the system. The return is through ceiling plenum. It is mentioned in the...
  16. PS

    Car Park Ventilation

    Yes, @dbill74. Thanks for the reply. That is the thing which confused me. I am observing it to be "NATURAL applies only during Fire/Smoke situation, whereas during car-fume extract it acts as a mechanical ventilation system and Open-sided ventilation is natural ventilation in both the...
  17. PS

    Car Park Ventilation

    Thanks ALL, for your kind replies. Given below is the link, I was referring to. http://www.proidea.hu/colt-hungaria-kft-228110/colt-jestream-cyclone-melygarazs-szellozteto-336888/a_9_d_23_1429781805045_colt_jestream_cyclone_garazsszellozteto_rendszer__en.pdf The image that was attached earlier...
  18. PS

    Car Park Ventilation

    Hello Professionals, I was reading an article about car park ventilation. It was mentioned there are three methods to ventilate car parks. (i) Open Sided Ventilation, (ii) Natural Ventilation, and (iii) Mechanical Ventilation. I can understand that mechanical ventilation differs from the other...
  19. PS

    Pressure Drop/Head Loss calculation

    @Jams: Thanks for your reply. There are two types of losses in pipes: Major losses and Minor Losses. Major Losses are due to the frictional drag between the walls of the pipe and fluid layers. This loss is significant only in straight pipes and often NEGLIGIBLE in pipe fittings such as elbows...
  20. PS

    Role of Valve Authority in Valve Selection

    Thanks a lot @quark, @Drazen, @SAK9, @ChasBean1.

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