The Orifice Meter and Gas Measurement TAlc.
t1
t.,-..0410
I
Values of .11
Per second Per minute Per hour Per 24 hours
N.
Vahle-s of A
Fog ru It
I.( gal
For lbs.
OW70;
0.0i 72.
0.4592 27.55
.;,433 206.1 4947
0.4773 28.64
6612
1718
41240
TABLE 2. CORRECTION FACTORS (R) FOR VELOCITY OF APFROACH d
R
R
0.30 0.35 0.40 0.45 0.50
1.0015 1.0026 1.0047 1.0075 1.0115
0.55 0.60 0.65 0.70 0.75
1.0170 1.0247 1.0348 1.0471 1.0637
If velocity of approach be neglected and the factor R be omitted from equations (3) and (4), the resulting flow computation will be in error by less than one-tenth of one per cent for less than one per cent for cent for
less than 027; by
d less than 0.48; and by less than two per
less than 0.57.
When a mercury float type differential gauge (which has been graduated in inches of water for use in measuring air or gas) is used for measuring liquids, the mercury should be covered by the liquid being measured, and the apparent value of h read on the gauge must
then be multiplied by (1 13.58), or, what amounts to the same thing, the flow, computed by the observed value of h, must be multiplied by 1/17 0.07364G. (b) Under adiabatic conditions, where no energy is added to or subtracted from the fluid, the increase in velocity required for it to pass through the orifice must be gained at the expense of the intrinsic energy of the fluid itself. In this case there is a change in
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