ChrisF11
27-03-2014, 03:05 PM
I am currently reviewing a ventilations system design for a 6 floor office building.
The original design was medium to high velocity (5-6m/s for an office) which has now been amended to try and convince us that we can use the existing risers.
The new ventilation flow diagrams show velocities of 1-2m/s second in the risers and 4-6m/s in the branches. Additionally the pressure drops range from 0.2pa/m to 1.9pa/m.
I am not alone in thinking that no design methodology ahs been applied to this (equal pressure drop/velocity method) and that these wide ranging values for pressure drop and velocity are not good practise. In fact would it be correct of me to assume we will have fan, noise and flow problems throughout the system?
A bit of confirmation would be appreciated in this because I am trying to convince building management the contractor is trying to do it on the cheap to save money by using the existing risers!!!!
The original design was medium to high velocity (5-6m/s for an office) which has now been amended to try and convince us that we can use the existing risers.
The new ventilation flow diagrams show velocities of 1-2m/s second in the risers and 4-6m/s in the branches. Additionally the pressure drops range from 0.2pa/m to 1.9pa/m.
I am not alone in thinking that no design methodology ahs been applied to this (equal pressure drop/velocity method) and that these wide ranging values for pressure drop and velocity are not good practise. In fact would it be correct of me to assume we will have fan, noise and flow problems throughout the system?
A bit of confirmation would be appreciated in this because I am trying to convince building management the contractor is trying to do it on the cheap to save money by using the existing risers!!!!