MEPworx - Additional Margins for Ducting

By Gary Mann

Generally, MEPworx does not add additional allowances by default, see….

“BSRIA Design Checks for HVAC - A quality control.   8. Avoid unnecessary use of margins.”

In Ducting, MEPworx defaults to the industry adopted leakage allowance factors so that testing of low-Pressure Duct systems is not required. The calculation will include a factor based on the total surface area of the duct installation. See below.  100% means that you want to allow for the worst duct fitters, stale mastic, substandard duct tape and poor site conditions.  0% implies that you do not want any margins added to the flow rate, remembering that rectangular slip joints are difficult to guarantee corner seals.

Setting this to zero percent implies that you can guarantee that no leakage will occur by use of a factory fitted double seal made of EPDM rubber which requires no further sealing e.g. (Lindab Safe). Below is a detailed extract from the MEPworx, context sensitive, Help (F1).

I hope this helps with setting up your next project. Thank you.       

gary.mann@cadline.co.uk