Woodward 3171A, Руководство по эксплуатации продукта, Страница: 30 / 47

EM35MR1/3171A Gas Valve Manual 26731
20 Woodward
Valve Sizing and the Effective Area Tables
Once the effective area has been determined, move to the effective area tables
later in this chapter. The effective area table has % valve travel, demand mA,
and valve angle listed in the first three columns. The following ten columns list
the valve effective area for pressure ratios (P2/P1) from 0.05 to 0.95 respectively.
To pick the proper size valve for an application, move to the sheet that has a
value for effective area greater than or equal to that determined above in the 100
percent travel row for the applicable pressure ratio column.
Woodward recommends that no less than 60% valve travel be used
for the full control range. Using less than that could cause instability
problems as the system attempts to control at very low increments of
travel.