Ventilation Systems: Operation and Testing - GHDonline
Ventilation Systems: Operation and Testing - GHDonline
Ventilation Systems: Operation and Testing - GHDonline
You also want an ePaper? Increase the reach of your titles
YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.
Bench Grinder Exhaust <strong>Ventilation</strong><br />
1<br />
Duct diameter = 3 inches<br />
Area = 0.0668 ft 2 V = 4490 fpm<br />
2 3<br />
• If there are no losses from the<br />
grinder hood entry then:<br />
SP 1 + VP 1 = SP 2 + VP 2<br />
but: SP 1 = 0 <strong>and</strong> VP 1 0<br />
we then have:<br />
0 = SP 2 + VP 2<br />
or SP 2 = (-VP 2 )<br />
• from V = 4005 (V P ) 0.5<br />
• VP 2 = (4490/4005) 2<br />
• VP 2 = 1.26 in w.g.<br />
• then: SP 2<br />
= (-VP 2<br />
)<br />
SP 2<br />
= -1.26 in w.g.<br />
Bench Grinder Exhaust <strong>Ventilation</strong><br />
1<br />
S Ph<br />
Duct diameter = 3 inches<br />
Area = 0.0668 ft 2 V = 4490 fpm<br />
2 3<br />
• However there are losses thru the grinder hood entry<br />
S P2 = (-V P2 + h e ) where h e is the energy loss of the hood entry<br />
• Static pressure (S P ) must decrease due to acceleration of air up to the duct velocity<br />
• F h is defined as the energy loss coefficient<br />
• Energy losses will be measured as a function of the velocity pressure in the system<br />
h e = (F h ) (VP)<br />
• Now we define the static pressure at the hood as S Ph<br />
• S Ph is also called the hood static suction <strong>and</strong> is the absolute value of S P2<br />
11
Change language