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V5097A-E INDUSTRIAL GAS VALVES
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65-0230—07
3.
Find the pressure drop across the first valve by
assuming it to be 45 percent of the total pressure drop.
4.
Find the valve size from Fig. 1.
5.
The second valve will be the same size as the first valve.
How to use the Specific Gravity Conversion
Factors (Fig. 3)
Listed valve capacity ratings are based on 0.64 specific gravity
(sg gr) gas. When the required cfh capacity is known for gas of
other specific gravity, it can be converted to the 0.64 equivalent
by using the correct multiplying factor obtained from Fig. 3.
For example, a valve capacity of 2670 cfh based on 0.72 sp gr
gas is required. What valve capacity, based on 0.64 sp gr gas,
will be required?
On the vertical scale of Fig. 3, find 0.72 specific gravity
(left side of figure). Draw a line horizontally from that point
to the right to intersect the curve, then move straight down
the chart to the bottom scale and read the conversion factor
(1.06, in this example).
Multiply the 2670 cfh by the conversion factor (1.06) to obtain a
valve capacity of 2830 cfh.
Applying this number to Fig. 4, assuming a 1 in. wc pressure
drop, use a 2 in. (large body) V5097 Valve for that flow (step 8
of Gas Valve Sizing).
Fig. 3. Specific gravity conversion factors.
2.50
2.25
2.00
1.75
1.50
1.25
1.00
0.50
0.25
0
0.6
0.7
0.8
0.9
1.0
1.1
2.0
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
0.75
CONVERSION FACTORS
SPECIFIC GRA
VITY
0.72
1.06
EXAMPLE
M17879