6
Sample location TG BLD (Figure 7) depicts SF6 con-
centrations ranging from 60 to 100 ppb with two samples
60 ppb. This location is inby the BEP on the tailgate side of
the longwall panel and is affected by dilution from bleeder
air entering the mine ventilation system at the headgate side
of the panel, air exiting the active longwall face to the tail-
gate entry, and air traveling in the adjacent tailgate entries.
Figure 8 shows the SF6 concentration measurements
for sample location TG BLD BEP. The sample concentra-
tions generally ranged from 325 ppb to 375 ppb. This sam-
ple location receives the face ventilation air coursed down
the longwall face as well as any air in the secondary flow
path behind the shields and air from the mined panel gob
area adjacent to the tailgate entry. These locations are under
pressure from the bleeder fan at the back end of the bleeder
system. The TG BLD BEP sample location is critical as it
represents any gas in the ventilation system prior to ‘fresh’
air mixing and dilution.
Test Series C
For Test Series C, the individual average SF6 concentrations
for each test are shown in Table 6. Concentration mea-
surements at sample locations TG #1, GVB, GOB, GOB
MID, and FACE average 0 ppb SF6. Minimal amounts
of SF6 were measured at TG #2, TG #3, and the TGCG
sample locations (2 ppb SF6). Sample location TGCG SF6
concentration measurements are affected by the secondary
ventilation flow path directly behind the tailgate shields
and proximity to the insertion points in the corner of the
tailgate gob shown in Figure 2 [13]. This sample location is
located directly behind the tailgate shields in the panel gob
and is influenced by the secondary flow path of longwall
face air created by resistance of the longwall face. The GVB
Figure 6. Individual SF
6 gas concentration sample results for
the TGCG location in Test Series A
Figure 7. Individual sample SF
6 concentration results for
the TG BLD location in Test Series B
Figure 8. Individual sample SF6 concentration results for
the TG BLD BEP location in Test Series B
Table 5. Test Series B average SF6 concentration measurement at each sample location
Series B TG#1 TG#2 TG#3 TG BLD TGCG TG BLD BEP GVB GOB GOB MID FACE
Test 1 0 0 0 76 0 331 0 3 0 0
Test 2 0 0 0 82 0 346 0 3 0 0
Test 3 0 0 0 75 0 319 1 3 0 0
Series Average 0 0 0 77 0 332 1 3 0 0
Sample Location Average SF6 (ppb)
Sample location TG BLD (Figure 7) depicts SF6 con-
centrations ranging from 60 to 100 ppb with two samples
60 ppb. This location is inby the BEP on the tailgate side of
the longwall panel and is affected by dilution from bleeder
air entering the mine ventilation system at the headgate side
of the panel, air exiting the active longwall face to the tail-
gate entry, and air traveling in the adjacent tailgate entries.
Figure 8 shows the SF6 concentration measurements
for sample location TG BLD BEP. The sample concentra-
tions generally ranged from 325 ppb to 375 ppb. This sam-
ple location receives the face ventilation air coursed down
the longwall face as well as any air in the secondary flow
path behind the shields and air from the mined panel gob
area adjacent to the tailgate entry. These locations are under
pressure from the bleeder fan at the back end of the bleeder
system. The TG BLD BEP sample location is critical as it
represents any gas in the ventilation system prior to ‘fresh’
air mixing and dilution.
Test Series C
For Test Series C, the individual average SF6 concentrations
for each test are shown in Table 6. Concentration mea-
surements at sample locations TG #1, GVB, GOB, GOB
MID, and FACE average 0 ppb SF6. Minimal amounts
of SF6 were measured at TG #2, TG #3, and the TGCG
sample locations (2 ppb SF6). Sample location TGCG SF6
concentration measurements are affected by the secondary
ventilation flow path directly behind the tailgate shields
and proximity to the insertion points in the corner of the
tailgate gob shown in Figure 2 [13]. This sample location is
located directly behind the tailgate shields in the panel gob
and is influenced by the secondary flow path of longwall
face air created by resistance of the longwall face. The GVB
Figure 6. Individual SF
6 gas concentration sample results for
the TGCG location in Test Series A
Figure 7. Individual sample SF
6 concentration results for
the TG BLD location in Test Series B
Figure 8. Individual sample SF6 concentration results for
the TG BLD BEP location in Test Series B
Table 5. Test Series B average SF6 concentration measurement at each sample location
Series B TG#1 TG#2 TG#3 TG BLD TGCG TG BLD BEP GVB GOB GOB MID FACE
Test 1 0 0 0 76 0 331 0 3 0 0
Test 2 0 0 0 82 0 346 0 3 0 0
Test 3 0 0 0 75 0 319 1 3 0 0
Series Average 0 0 0 77 0 332 1 3 0 0
Sample Location Average SF6 (ppb)