TB 9-6685-316-50
(21) If dP of equation 3 is negative (-), compute the additional weight required on
the TI to obtain a reference pressure from the equation.
Equation 5.
W2 = (dP)(0.02)
Where: w2 = weight (lb) to be added to TI to obtain a reference pressure (using weight set (A1) to the
nearest nominal weights nation).
dP = difference between nominal and developed pressure from equation 3 above
0.02 = nominal piston area of TI (in.2)
(22) Apply pressure to equipment setup, using handpump while slowly rotating
weights clockwise until one or both units are floating. Monitor nominal pressure using
standard pressure gage indication.
(23) Floating will be obtained when weights are rotating clockwise on both units
with bottom surface of one weight table 1/4-inch above either the TI or standard cylinder
housing.
(24) If the standard weight table is floating, place 1/4 oz 1/2 oz and 1/16 oz
calibration weights from (A1) on the standard weight table. If the standard weight table
falls and the TI weight table rises, the TI is within tolerance. If the standard weight
table does not fall, the TI is not within tolerance.
(25) If the TI weight table is floating, place 1 oz, 1/2 oz and 1/16 oz calibration
weights from (A1) on the TI weight table. If the weight table falls and the standard
weight table rises, the TI is within tolerance. If the TI weight table does not balance the
TI is not within tolerance.
(26) Release pressure from equipment setup.
(27) Repeat (18) through (26) above for two extremes as shown in. table 6. The
5000 of equation 3 above will be changed to the nominal pressure of table 6, and the
calibration weights of paragraphs (24) and (25) above will be changed to the calibration
Table 6. Low and High Extremes (High Range)
Weight combination, including
Calibration weight (A1)
Nominal
(Standard)
Test
pressure
Test Instrument
(Standard)
floating
instrument
(psi)
Qty
Press. unit
Qty
Press. unit
(oz)
floating (oz)
9000
1
475
1
950
1, 1/4, 1/8,
2, 1/2, 1/4 and
17
500
8
1000
& 1/16
1/8
1000
1
475
1
950
1/8 & 1/32
1/4 and 1/16
1
500
b. Adjustments. No adjustments can be made.
a. Performance Check
(1) Disconnect high-pressure hose from standard (A5), and install low-range