Tisch Environmental TE-5170DV, Operation Manual

Page: 26 / 40

TE-5170DV-BL 26 Operations Manual
Use of Look-Up-Table to Determine Flow Rate
(NOTE: Individual Look-Up Tables will vary.)
1. Suppose the ambient conditions are:
Temperature: T
a
= 20
o
C
Barometric Pressure: P
a
= 749.3 mm Hg (this must be station pressure which is not
corrected to sea level)
2. Assume system is allowed to warm up for stable operation.
3. Measure filter pressure differential, P
f
. This reading is the set-up reading plus pick-up reading
divided by 2 for an average reading. This is taken with a differential manometer with one
side of the manometer connected to the stagnation tap on the filter holder (or the Bulkhead
Fitting) and the other side open to the atmosphere. Filter must be in place during this
measurement.
Assume that:
Set-up Reading (clean filter): P
f
= 12.6 in H
2
O
Pick-up Reading (dirty filter): P
f
= 16.0 in H
2
O
P
f
= (12.6 + 16.0)/2 = 14.3 in H
2
O.
4. Convert P
f
= to same units as barometric pressure.
P
f
= 14.3 in H
2
O / 13.61 x 25.4 = 26.687729 mm Hg
P
f
= 26.69 mm Hg
5. Calculate pressure ratio.
P
o
/P
a
= 1 - (P
f
/P
a
)
NOTE: P
f
and P
a
MUST HAVE CONSISTENT UNITS