ASME B31.3 Table 323.2.2 Note 6 excludes impact testing when the maximum obtainable specimen has a width along the notch of less than 0.098 inch. So if you were trying to test a circumferential weld in an existing pipe joint, what pipe sizes/schedules are excluded from impact testing because...
Typically, I've been designing HVAC systems where the return air is about 80 - 90% of the supply air so I have not been worrying about building pressurization. However, now I have a church with a vav ahu and a significantly reduced RA flow. So I have a few questions:
1. At what point do you...
I have a boiler exhaust vent that I am trying to figure out the minimum required insulation thickness for. The vent is a stainless steel double wall pipe with a 1" air gap.
I am trying to select the fiberglass insulation thickness to keep the surface temperature below 130 degrees F for...
I've got to run some piping from two 1000 gallon tanks outside to boilers inside a facility.
I'm assuming that just like chilled water, there is a recommended velocity/pressure drop that is typically used when sizing pipe to simplify the process. This velocity is typically related to errosion...
When selecting a pump for a closed loop hot water system, how do you calculate the NPSHa?
NPSHa = Static Height - Inlet Friction - 3' Safety Factor
Is the static height calculated from the highest point in the system?
For inlet friction, how far back in the pipe line do you go to calculate...
I have a building in central florida that is being used to dry parachutes. The existing ahu to dry the parachutes is an off the shelf dx split unit. Consequently it takes a week to dry the parachutes. One of the mods I am working on is to replace the ahu so that drying time is reduced to a...
I am doing a load calc for a building that has an open water tank in it. I've found a formula for calculation the evaporation rate for the tank. However, my load software requires a value in btuh not lb/hr. How do I go about figuring out how many btuh this is?
The only thing I could find...
The Florida Mechanical Code, Uniform Building Code, and International Mechanical Code all call for restrooms to have a certain level of exhaust typically 50 cfm per water closet or 2 cfm per square foot. This is not the same as a "negative pressure" requirement - my mistake, but it is...
I have a long rectangular computer server room (20' x 70')that I am designing a underfloor hvac system for. The underfloor system will provide air directly to the servers through cut-out floor panels. The problem is that the client wants the hvac units in the far corner of the room. With the...
I have a project to design a parachute drying tower. Basically, it's a tall metal building where they hang parachutes on hoists and run the A/c units heater to dry the chutes. I'm looking for some help on how to calculate drying times and/or how much heat its going to take to dry a parachute...
I have used both Trane Trace 700 and Elite's CHVAC. Trace 700 is very detailed with its input and outputs. This can be good, but also can take quite a bit of time to enter inputs. Trace 700 also does energy calculations, so alot of the input fields are only required if you want to do the...
I do mostly commercial hvac design but I'm not aware of any differences for FCU's for residential applications versus commercial. So maybe I can be of some help.
All of the major manufacturer's I have dealt with (Trane, Carrier, etc.) have a drain pan the width of the coil located beneath the...
When you are sizing your chilled water piping and pump, do you typically include the pressure drop for such items as the suction diffuser, flex connections, air separator, etc. or are you mainly concerned with the coil, fittings, valves and such? In all the examples I've seen, only the main...
Thanks for your help everyone! I was thinking that if your fan is correctly sized for your ductwork and you stayed below the air velocities recommended by ASHRAE you would be okay. But then I started thinking about how it is recommended to keep your pressure drop at 0.1"/100 ft. Now that...
