TB 9-6685-316-50
(4) Place the 95-psi, eight of the 100-psi, four of the 20-psi, and four of the 5-psi
weights supplied with (A5) on the standard piston.
(5) Compute the deviation of the developed pressure from the nominal pressure
of 1000 psi from the Report of Calibration furnished with the standard, using the
following equations:
Equation 1.
dP 1000 - PR g
gc
where: dP = difference between nominal pressure and developed pressure (psi).
1000 = nominal pressure (psi)
PR = Developed pressure (psi) from Report of Calibration furnished with the standard.
gc = local gravity (furnished with Report of Calibration)
g = 980.665 or 980.217 cm/sec2 (design gravity of piston and cylinder combination).
(6) Compute the weight required to obtain a reference pressure from the
equation:
Equation 2.
W = (dP)(0.1)
where: W = weight (lb) required to obtain a reference pressure.
dP = difference between nominal and developed pressure from equation 1 above.
0.1 = nominal piston area(in.2).
(7) If dP of equation 1 above is positive (+), place a weight combination (using
avoirdupois weight set A1) equal to W of equation 2 above (to the nearest nominal
weight combination) on the standard.
(8) If dP of equation 1 above is negative (-), place a weight combination (using
avoirdupois weight set A1) equal to W of equation 2 above (to the nearest nominal
weight combination) on the TI.
(9) Apply pressure to equipment setup, using handpump while slowly rotating
weights clockwise until one or both units are floating. Monitor nominal pressure, using
pressure gage indication.
(10) Floating will be obtained when weights are rotating clockwise on both units
with bottom surface on one weight table about 1/4-inch above cylinder.
(11) Place 1, 1/2, 1/16, and 1/32 oz of calibration weight from (A1) on the floating
weight table. If this weight table falls and the opposite weight table rises, the TI is
within tolerance. If this weight table does not fall, the TI is not within tolerance.
(12) Release pressure from equipment setup.
(13) Repeat (3) through (12) above for two extremes as shown in table 5. The 1000
of equation 1 above will be changed to the nominal pressure of table 5, and the
calibration weight of step (11) will be changed to the calibration weight of table 5. The
high range piston and cylinder must be installed in the standard for pressures above
1000 psi.
8