7
Test 1—Chamber with access door to open outwards
(August 9, 2022)
Prior to starting the test, the pressure chamber was
inspected for safe conditions, the pressure gages zeroed,
the hand-held instruments set to record the field data, and
the personnel doors closed. The test started by opening the
pressure control valves V1 and V2 and setting the regulator
to allow a minimum flow rate. This was followed by record-
ing barometric pressure and the pressure differential across
the chamber walls, and checking for gas leakage into the
surrounding area. The process was repeated for different gas
flow rates.
Chronology of Events – August 9, 2022
• 11:25 AM. Regulator R1 set to minimum flow, valves
V1 and V2 were open. Pressure gages: G1 =400 kPa
(58 psi), G2 =0, DP2-1 =42 Pa (0.17 in wg)
• 11:30 AM. Regulator position was increased by ½
turn. Pressure gages recorded: G1 =385 kPa (56 psi),
and G2 =20.7 kPa (3 psi), and DP2-1 =243 Pa
(0.97 in wg)
• 11:37 AM. Regulator position increased by another
½ turn. Gages: G1 =365 kPa (53 psi), and G2 =
20.7 kPa (3 psi), and DP2-1 =492 Pa (1.97 in wg)
• 11:41 AM. Regulator increased by another ½ turn.
Gage pressures: G1 =379 kPa (55 psi), and G2= 34
kPa (5 psi), and DP2-1= 630 Pa (2.52 in wg) 11:42
AM. Regulator position increased by ½ turn. Gage
pressures: G1 =338 kPa (49 psi), and G2 =28 kPa
(4 psi), and, DP2-1 =808 Pa (3.23 in wg)
• 11:48 AM. Significant leakage of nitrogen through
door gaskets was detected (O2 19.5%). The nitro-
gen control valves were shut off. It took 20 sec. to
depressurize the chamber.
Figure 7 shows barometric pressure variations (actual,
not standardized), and pressure differentials recorded dur-
ing this test. Notice that when the gas flow rate increased,
the pressure differentials across the seal and stopping
increased rapidly and remained constant thereafter, indi-
cating that both walls can hold pressurized nitrogen with
reduced leakage. The test was repeated for increased flow
rates. It was stopped when the nitrogen gas leakage from
the chamber reduced the oxygen level in the access drift to
less than 19.5%. Table 1 summarizes the differential pres-
sures across the chamber walls.
Test 2—Chamber with access door to open inwards
(June 7, 2023)
Once the access doors in the Kennedy stopping were
reversed, the chamber was inspected for safe conditions,
the hand-held instruments set to record the field data,
and the regulator set to allow for a minimum flow rate,
the test started on June 7, 2023. Initially, the chamber was
pressurized so that the gage pressure across the stopping
reached 250 Pa (1 in wg). Then, the chamber was inspected
again for unsafe conditions. Having found it to be in good
standing, the gas flow rate was increased by adjusting the
Figure 6. Pressure differential series after nitrogen gas injection (December 2–3, 2021)
Test 1—Chamber with access door to open outwards
(August 9, 2022)
Prior to starting the test, the pressure chamber was
inspected for safe conditions, the pressure gages zeroed,
the hand-held instruments set to record the field data, and
the personnel doors closed. The test started by opening the
pressure control valves V1 and V2 and setting the regulator
to allow a minimum flow rate. This was followed by record-
ing barometric pressure and the pressure differential across
the chamber walls, and checking for gas leakage into the
surrounding area. The process was repeated for different gas
flow rates.
Chronology of Events – August 9, 2022
• 11:25 AM. Regulator R1 set to minimum flow, valves
V1 and V2 were open. Pressure gages: G1 =400 kPa
(58 psi), G2 =0, DP2-1 =42 Pa (0.17 in wg)
• 11:30 AM. Regulator position was increased by ½
turn. Pressure gages recorded: G1 =385 kPa (56 psi),
and G2 =20.7 kPa (3 psi), and DP2-1 =243 Pa
(0.97 in wg)
• 11:37 AM. Regulator position increased by another
½ turn. Gages: G1 =365 kPa (53 psi), and G2 =
20.7 kPa (3 psi), and DP2-1 =492 Pa (1.97 in wg)
• 11:41 AM. Regulator increased by another ½ turn.
Gage pressures: G1 =379 kPa (55 psi), and G2= 34
kPa (5 psi), and DP2-1= 630 Pa (2.52 in wg) 11:42
AM. Regulator position increased by ½ turn. Gage
pressures: G1 =338 kPa (49 psi), and G2 =28 kPa
(4 psi), and, DP2-1 =808 Pa (3.23 in wg)
• 11:48 AM. Significant leakage of nitrogen through
door gaskets was detected (O2 19.5%). The nitro-
gen control valves were shut off. It took 20 sec. to
depressurize the chamber.
Figure 7 shows barometric pressure variations (actual,
not standardized), and pressure differentials recorded dur-
ing this test. Notice that when the gas flow rate increased,
the pressure differentials across the seal and stopping
increased rapidly and remained constant thereafter, indi-
cating that both walls can hold pressurized nitrogen with
reduced leakage. The test was repeated for increased flow
rates. It was stopped when the nitrogen gas leakage from
the chamber reduced the oxygen level in the access drift to
less than 19.5%. Table 1 summarizes the differential pres-
sures across the chamber walls.
Test 2—Chamber with access door to open inwards
(June 7, 2023)
Once the access doors in the Kennedy stopping were
reversed, the chamber was inspected for safe conditions,
the hand-held instruments set to record the field data,
and the regulator set to allow for a minimum flow rate,
the test started on June 7, 2023. Initially, the chamber was
pressurized so that the gage pressure across the stopping
reached 250 Pa (1 in wg). Then, the chamber was inspected
again for unsafe conditions. Having found it to be in good
standing, the gas flow rate was increased by adjusting the
Figure 6. Pressure differential series after nitrogen gas injection (December 2–3, 2021)