Momentum and Friction Loss vs Static Loss

[Brandon181]

My process group provides us with "allowable" pressure drops for our shell and tube exchangers. Using HTRI we design an exchanger and it reports the "calculated" pressure drop for the unit. On certain designs we have done, the "calculated" pressure drop was greater than the "allowable" given to us. However, when looking at the stream properties, the pressure drop can be summed up by the friction loss, static head loss, and momentum loss. I have been told that the static head loss can be ignored, and if the combined pressure drop due to friction and momentum is still below the "allowable", than this is acceptable. Is this thinking correct? Can any static head loss be ignored in the HTRI "calculated" pressure drop? (This occurrence is common in reboilers)

Ex:
Allowable: 0.5 psi
Calculated: 1.16 psi
Friction and Momentum Loss: 0.17 psi
Static Loss: 0.99 psi

0.5 < 1.16 ------->FAIL
0.5 > 0.17 ------->PASS

 

[BigInch]

It would seem to indicate that the static head available is greater than the dynamic losses. Meaning, as long as the dam has water higher than the spillway, water will flow out. Hard to say for sure, unless I see the calculation sheet.

"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek