| RELIEF VENT SIZING FOR DUST APPLICATIONS | ||||||||
| NFPA-68, 1998 Edition | ||||||||
| Client Information | ||||||||
| Company Name: | ||||||||
| Contact Name : | ||||||||
| Telephone # : | Proprietary and Confidential | |||||||
| Fax # : | ||||||||
| Vent Application: | ||||||||
| Notes: | ||||||||
| We have prepared this sizing profile based on data provided by you or published by NFPA, unless otherwise noted. Further, it must be recognized that it is not rational to consider an active process system to be adequately protected by isolating a portion of it only for explosion protection assessment. Henderson accepts no liability for the information contained herein and we reserve the right to revise the sizing and our applicable quotation, if required, upon receipt of any additional information that mey be relevant to the application. | ||||||||
| Is the enclosure cylindrical (Y/N) ? | N | |||||||
| Enter the Width of Enclosure? | 1.07 | m | ||||||
| Enter the Height of Enclosure? | 3.25 | m | If there is a discharge duct, is it >0m or <3m (Y/N)? | If there is a discharge duct, is it >=3m or <=6m (Y/N)? | ||||
| Enter the Length of Enclosure? | 7 | m | ||||||
| Pmax | Pred | Volume | Kst | Pstat | Equivalent D | |||
| (bar) | (bar) | (m3) | (bar*m/s) | (bar) | (m) | |||
| 10.30 | 0.99 | 2.41 | 202.00 | 0.10 | 2.10 | Y | N | |
| Note: Discharge ducts over 6m are beyond the scope of NFPA 68 sizing | ||||||||
| Av = | (3.264x10-5 x Pmax x Kst x Pred-0.569 + 0.27 x (Pstat - 0.1) x Pred-0.5) x V0.753 | |||||||
| Av = | 0.13372 | m2 = | 1.44 | ft2 | ||||
| Test for elongated vessel influence | ||||||||
| L/D = | 3.33165 | |||||||
| If 2< L/D <6 then the vessel is elongated and an additional relief area, DA, is required. | ||||||||
| If greater than 6, Chapter 8 sizing applies | ||||||||
| DA = | Av x (-4.305 x LogPred + 0.758) x Log(L/D) | |||||||
| DA = | 0.05390 | m2 = | 0.58 | ft2 | ||||
| Total vent area required given an elongated vessel and WITHOUT a discharge duct | ||||||||
| Av + DA = | 0.18762 | m2 = | 2.02 | ft2 | ||||
| The following applies only if there is a discharge duct. | ||||||||
| Discharge duct impact on Pred ---> P'red as a substitution in the formula for Av to get Av' | ||||||||
| Since discharge duct length is <3m, then P'red = 0.394(Pred^1.529) | ||||||||
| P'red = | 0.38979 | m2 = | 4.20 | ft2 | ||||
| Av' = | 0.22749 | m2 = | 2.45 | ft2 | ||||
| Additional vent area given discharge duct consideration with respect to Av' | ||||||||
| If 2< L/D <6 then the vessel is elongated and an additional relief area, DA', is required. | ||||||||
| DA' = | 0.29957 | m2 = | 3.22 | ft2 | ||||
| Total vent area required given an elongated vessel, WITH a discharge duct. | ||||||||
| Av' + DA' = | 0.52706 | m2 = | 5.67 | ft2 | ||||
| HIS-D98-V5 | Page 1 of 1 | |||||||
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