System Pressure vs Static Pressure
System Pressure vs Static Pressure
(OP)
I am busy Validating a Pharmaceutical HVAC Factory. In the documents there is a portion where I should calculate system pressure from the read data which is:
1. Supply Duct pressure
2. Return Duct Pressure
3. Primary Filter Differential Pressure
4. Secondary Filter Differential Pressure
5. HEPA Filter Differential Pressure
6. Coil Differential Pressure
What is the right formula for this parameter from the given data?
May someone please help me address this problem with special attention to whether I have to read Return Ducting Pressure as positive or negative.
1. Supply Duct pressure
2. Return Duct Pressure
3. Primary Filter Differential Pressure
4. Secondary Filter Differential Pressure
5. HEPA Filter Differential Pressure
6. Coil Differential Pressure
What is the right formula for this parameter from the given data?
May someone please help me address this problem with special attention to whether I have to read Return Ducting Pressure as positive or negative.





RE: System Pressure vs Static Pressure
RE: System Pressure vs Static Pressure
RE: System Pressure vs Static Pressure
BMug, for this industry we find ourselves cornered by requirements from people who don't understand HVAC. For their purposes, write down the supply duct static pressure. It might be 1 to 3 inches water column.
We know the value is meaningless without full static across the fan and the speed value at which those were recorded, but it's like filling out a psych form while waiting for a doctor... Put down 1.3 furlongs on the form and see if they come back with any questions...
RE: System Pressure vs Static Pressure
ChasBean what do you mean "cornered by requirements from people who don't understand HVAC"? can you give a typical example please to illustrate?
BTW, what area of the industry do you work in? consulting, contracting, else??
BMug, are you doing like a 'due diligence' on the design?
RE: System Pressure vs Static Pressure
Yes this is a periodic due diligence test on the equipment that we do 6monthly, yearly and once every two years depending on the type of the test.
Its basically is a requirement for Pharmaceutical production plants to ensure the tablets, etc are being produced in the claimed state as validated during start up just to respond to ChasBean1.
RE: System Pressure vs Static Pressure
RE: System Pressure vs Static Pressure
"Its basically is a requirement for Pharmaceutical production plants to ensure the tablets, etc are being produced in the claimed state as validated during start up"
means?
Waramanga, you want an example of HVAC requirements being imposed by those who don't have the background? Re-read the initial post. He's calculating "system pressure from the read data" which is a bunch of pressures. There's no definition of what's required or why, but it's needed by the "documents."
Sorry I was crass in my response, but I'm pretty comfortable in this industry and your initial post left me perplexed, to say the least, about your need to validate HVAC without any sort of background in it.
You listed a bunch of pressures at different HVAC points and wanted a formula for it(?)
Thanks, CB
RE: System Pressure vs Static Pressure
OP is validating a pharmaceutical manufacturing facility, which must be done to ensure FDA approval. Why not help him understand how to find the system pressure correctly instead of belittleing the work he is doing. Pharmaceutical manufacturing facilities hvac design is my industry btw.
RE: System Pressure vs Static Pressure
ChasBean1 your responses helped as well but as you pointed out that these values do not help out if the full static pressure across the fan is not recorded. That basically was my line of questioning as I do understand HVAC maybe not as much as you do.
I am in the process of Reviewing Validation Documents and I saw some of these tests that have been there for years and it was when I picked out something was not right hence the request for information from colleagues in case I was missing some point.
MechEngNCPE thanks for the Valuable help as you indicated on here that you are in this field I look forward to interacting with you more on the subject as I am basically specialising in Pharmaceutical Facilities.
RE: System Pressure vs Static Pressure
RE: System Pressure vs Static Pressure
Back to the OP...
If I saw a list of numbers like this on a form asking for a total - I would subtract all the differential pressures and the return duct pressure from the supply duct pressure.
What else could the form be asking for? What it hopes to achieve is another story altogether.
RE: System Pressure vs Static Pressure
These curves can be modified with fan RPM's changes.
Happy reading.