Include entrance/exit losses as the air speeds up / slows down to enter/exit your rectangular flow path.
Hints here:
https://www.engineeringtoolbox.com/minor-loss-air-ducts-fittings-d_208.html
Suggest doing some searches related to entrance and exit losses.
AMCA knows what a fan curve that incorporates velocity pressure looks like:
https://www.amca.org/educate/articles-and-technical-papers/amca-inmotion-articles/straightening-out-fan-curves.html
Also from AMCA...
"fan curves are no good if they account for velocity pressure."
No good for whom?
It benefits the vendor to sell the higher number. Then a shortfall in performance can be blamed on the engineer because they didn't account for what the vendor actually advertised.
Pump vendors routinely sell...
The OP was correct: the discharge velocity pressure matters in a technically correct reading of a fan curve.
But the distinction is often ignored. There is a large amount of sloppiness in HVAC “engineering.” We get away with it because there are large uncertainties and safety factors. It is...
What 'pros' are you claiming while trying "to convince someone that is unnecessary to bypass to the tower Basin?"
Two 'cons' to completely bypassing the basin:
1. Water treatment chemicals in the basin will not be refreshed while it is bypassed. Depleted chemicals will be less effective in...
What is the cost of this system?
What would be the cost of hiring a professional to design it?
Would the cost of having it designed for the particular situation be less than the cost of a few cattle dying if a design gleaned from 30+ posts on a free internet forum fails?
thread403-435647
My conclusion after reading the referenced thread, etc.:
For a bell mouth inlet on a rectangular duct in a return air plenum: using a 6” bell length with 45-degree sides is probably adequate – if it can fit in the available space.
Some TL;DR for that conclusion:
As said in...
I am not sure this is true: "the Ideal gas law states that there should be a temperature drop after the obstruction."
As I recall:
Throttling (without heat transfer) is a constant-enthalpy process
The enthalpy of an ideal gas is a function only of temperature.
So I wouldn't expect any...
Thank you, PEDARRIN2.
I was skeptical of the engineer's recommendation.
Taken to an extreme, one might claim that (with a large enough drain line) a single vent could suffice for a building of any size because the IPC places no limit on the length of a combination waste and vent.
And even...
Insulation isn't needed if you can count on the given values:
Dew point temperature = 52.25 F
Condensate drain temperature is 53.6 F
But, as cautioned by EnergyProfessional, the dew point temperature in the ceiling void is not controlled and might climb above the condensate drain temperature...
Hello,
Please help regarding advice from someone with more venting experience than I have.
I think a vent is needed for the most remote floor drain in the image below.
The EOR says the vent on the sump pump is sufficient.
This may be accurate if: 1) it can be treated as a "combination waste...
Which vibration isolator complies with a specification that requires a "minimum static deflection of 1 inch" (where the load imposed on the isolator is 300 pounds):
Proposed by the contractor: An isolator with a rated deflection of 1 inch at a rated load of 500 pounds in the manufacturer’s...
Gregory:
The supplier wants to include the weight of the pipe. I think that is a mistake. The pump supplier wants no pipe weight on their connections. No pipe weight can be transmitted to the connections if the flex connectors are doing their jobs.
Artisi:
The thrust force was my concern in...
It seems to me that pump vibration isolators need to support:
1. The weight of the pump
2. The weight of the water in the pump
3. The weight of the water (only) in the drop to the pump
The supplier of vibration isolators on my project does not seem to share this view.
I understand that pump...
Doesn't the force on the support leg of a suction diffuser depend on:
[ol 1]
The pressure inside the housing?
The size of the inlet pipe?
[/ol]
Page 11 of the instructions for installing a suction diffuser says only...
I hear that coalescing air separators are much quicker about removing air from a system. They are also supposed to be better at removing "dissolved" air.
They are also filled with media that seems subject to clogging (hence, higher maintenance cost), and I think their purchase price and...
Is the industry moving away from lead-free chrome-plated brass ball valves for domestic water systems?
As there was some confusion during a conversation with one supplier, I am referring to the ball being chrome-plated, not the valve body.
A Brand-X supplier said they stopped making them...
The flow rate through the vent pipe is used to calculate value of V/V* for Chart II-1 in Appendix II of ASME B31.1.
But Chart II-1 doesn't plot values of V/V* for values of f(L_max/D) greater than 1.0.
The implication seems to be that if the value of f(L_max/D) is greater than 1.0, then the...
Manufacturers of drip pan elbows seem quick to "highly recommend" their use, but they may not be practical when a vent line must run through several stories from a basement mechanical room to a roof.
The following may be optimistic maximum lengths for vent lines from drip pan elbows for...
When is it recommended, or not, to use the flange taps provided by a pump manufacturer for connecting pressure gauges?
The detail at the link below shows one gauge connection to the flange tap on the suction side of the pump; the other is downstream of the flex connector on the discharge side...
