ASHRAE Velocity Limits? 1

[tmartin125]

A colleague of mine says ASHRAE duct design analysis cannot be relied upon for air velocities in excess of 12,000 fpm. As evidence he references ASHRAE's Friction Chart for Round Duct (See 21.8, Figure 9 in 2009 ASHRAE Handbook-Fundamentals) which only goes up to 12,000 fpm. Is it true that a different duct loss analysis method should be used for velocities exceeding 12,000 fpm? .

Note, it is understood that velocities this high are not recommended for design of typical duct sections. I am asking for special cases only where duct velocities above 12,000 fpm may be required. Thank you.

 

[EnergyProfessional]

what is your application? Pressure drop must be horrendous and you may have duct erosion. is it a rocket motor nozzle?
Yes charts are based on certain equations that are validated within certain ranges.
You can check in EES if that duct calculation has a wider range (and it also would account for pressure and temperature, unlike ASHRAE)

 

[Physics_Nerd]

12000 FPM is very high man, seriously is it a rocket??? it will most certainly burst the ducts we normally use

 

[willard3]

ASHRAE serves the Heating, Refrifgeration and Air Conditioning Engineers. airflow >12000 fpm is too high for any ventilation system, hence ASHRAE's caveat.

 

[show790]

sand Trap Louvers calculation ? i have 3200 CFM must go through sand trap louver ? i need how to calculate it