how to measure static pressure of AHU
how to measure static pressure of AHU
(OP)
May I ask how to measure the static pressure values of an AHU? Thanks
External pressure of AHU

Total pressure of AHU or static pressure of fan unit

Static pressure of fan inlet

Static pressure of fan outlet

Static pressure of upstream of filter

Static pressure of downstream of filter
External pressure of AHU
Total pressure of AHU or static pressure of fan unit
Static pressure of fan inlet
Static pressure of fan outlet
Static pressure of upstream of filter
Static pressure of downstream of filter





RE: how to measure static pressure of AHU
RE: how to measure static pressure of AHU
RE: how to measure static pressure of AHU
External pressure of AHU
link: https://lh5.googleusercontent.com/R2zXGkAU_7Xwk9Nv...
Total pressure of AHU or static pressure of fan unit
link: https://lh5.googleusercontent.com/rhsyn7ftRnmzR200...
Static pressure of fan inlet
link: https://lh6.googleusercontent.com/_gaNpS0JKjKGgChs...
Static pressure of fan outlet
link: https://lh4.googleusercontent.com/8Vg0o0JhVC82yrM8...
Static pressure of upstream of filter
link: https://lh6.googleusercontent.com/H-gEBRG7h82csKF1...
Static pressure of downstream of filter
link: https://lh3.googleusercontent.com/CBPNGzRbr3Zj29Fn...
If the pictures cannnot be shown, please click the links below the pictures. I don't know why sometime they can be shown, sometime cannot. Sorry.
RE: how to measure static pressure of AHU
RE: how to measure static pressure of AHU
RE: how to measure static pressure of AHU
Sorry, again the pictures cannot be shown. however, I have changed the hyperlink to anther account. I think this time the link should be valid and accessible. the pictures show how I use a manometer to measure different static values. I want to confirm whether I use the manometer correctly (both connecting to the manometer and the point I was measuring) Thanks.
External pressure of AHU
link: https://drive.google.com/file/d/0B6nZP28lo52eVktBN...
Total pressure of AHU or static pressure of fan unit
link: https://drive.google.com/file/d/0B6nZP28lo52ea3k5Z...
Static pressure of fan inlet
link: https://drive.google.com/file/d/0B6nZP28lo52eWU54T...
Static pressure of fan outlet
link: https://drive.google.com/file/d/0B6nZP28lo52eSXNTS...
Static pressure of upstream of filter
link: https://drive.google.com/file/d/0B6nZP28lo52eZzF5e...
Static pressure of downstream of filter
link: https://drive.google.com/file/d/0B6nZP28lo52eUDNkM...
RE: how to measure static pressure of AHU
You have got it right except maybe for the second which should be total pressure of fan not AHU.Willard is right. SP is irrelevant as there are both static and dynamic losses in a ductwork so we should only be looking at total pressure.I remember we have had this discussion on the forum before.The attached ASHRAE article will hopefully clear things up a bit?
RE: how to measure static pressure of AHU
RE: how to measure static pressure of AHU
RE: how to measure static pressure of AHU
I will prove it if you want to continue this post.
RE: how to measure static pressure of AHU
RE: how to measure static pressure of AHU
RE: how to measure static pressure of AHU
Does that mean static regain is not correct?
RE: how to measure static pressure of AHU
RE: how to measure static pressure of AHU
RE: how to measure static pressure of AHU
Back to academia, total pressure IS static plus velocity pressure. TSP on a fan curve however does not have a velocity pressure component.
RE: how to measure static pressure of AHU
i know cfm varies as rpm and sp varies as (rpm)^2
if i measure my ahu and find the following data,
original rpm=1805
new rpm =1355
original cfm= 8.1
new cfm=6.1
original sp= 1635
but new sp=730
for the rpm and cfm, it obeys the rule; however, sp breaks the rule
"Measure wrongly" is the only reason for getting such data?
any other reason?
thanks
RE: how to measure static pressure of AHU
can i draw the conclusion : the existing motor and fan may be changed by someone, that's why all the three parameters i measured do not match with the nameplate stick on the AHU?
thanks
RE: how to measure static pressure of AHU
RE: how to measure static pressure of AHU
cfm varies as rpm and sp varies as (rpm)^2
I think these rules is just theoretical rules for a theoretical specific design of the forward blade fan
so there are many factors cause difference in values between theoretical case and actual one
for example of these factors
number of blades
blades orientation (forward blade or backward blade)
curvature of blades
thickness of blades.....etc
RE: how to measure static pressure of AHU
peterchan222
But to be honest I think that all previous factors may affect on flow rate and power but The strange thing for me is to be the difference in static pressure
may be the point you measured sp in the AHU is wrong
RE: how to measure static pressure of AHU
RE: how to measure static pressure of AHU
first, when you measure pressure difference you should take two points in two ducts have the same size to avoid the effect of dynamic pressure
second, all points must be not in turbulence flow area, so your point in mixing box as shown in pictures is wrong because it makes false reading
RE: how to measure static pressure of AHU
RE: how to measure static pressure of AHU
RE: how to measure static pressure of AHU
important note: Don't forget that you should take points in the same duct size (the same cross section area of flow ) when measuring static pressure difference to avoid the effect of dynamic pressure
RE: how to measure static pressure of AHU