Heraeus HS 12, Руководство по обслуживанию, Страница: 75 / 282

Service Instructions HERAsafe HS/12/18
• 46 •
Valid: 05.2001 / 50060091 / A
B Field tests
Figure B2
Fig. B2, Test grid in the constricted work opening
B5 Inflow velocity test
Purpose of the test:
This test is performed to determine the values of the
inflow velocity and to determine the inflow/exhaust air-
flow volume rates. During this test, the inflow velocity
is measured directly or calculated.
Default values:
Exhaust filter exhaust area
HS 12,
A
1
.= 0.247 m² ( 2,653 ft
2
)
HS 18, A
1
.= 0.336 m² ( 3,62 ft
2
)
Actual inflow area of constricted opening for ane-
mometer (calculated method)
HS 12,
A
2
= 0.091 m² ( 0,982 ft
2
)
HS 18, A
2
= 0.137 m² ( 1,5 ft
2
)
Actual inflow area of normal opening
HS 12,
A
3
= 0.240 m² ( 2,583 ft
2
)
HS 18, A
3
= 0.360 m² ( 3,9 ft
2
)
Values to be determined:
Direct inflow velocity, V
1
in m/s (fpm).
Calculated inflow velocity, V
2
in m/s (fpm).
Direct inflow airflow volume rate ,R, in m³/h (ft³/min).
Calculated average value of inflow/exhaust airflow
volume rate,
R
2
in m³/h (ft³/min)
Apparatus:
Thermal anemometer or DIM ( Direct Inflow Meas-
urement )
Calibration of the apparatus:
The thermal anemometer and/or DIM must be cali-
brated in accordance with the manufacturer’s instruc-
tions or using wind tunnel tests.
Accuracy of the anemometer apparatus:
Accuracy of ± 0.01 m/s (± 2.00 fpm) or a maximum of
3% of the indicated airflow velocity.
Test conditions:
During the Inflow velocity or flow measurements, there
must be no objects in the safety cabinets work cham-
ber. The doors and windows of the room where the
cabinet is located must be closed (no draft).
Test grid in the work opening using an
anemometer:
The measurements are performed directly in the con-
stricted work opening.
The measuring points are located within a distance
B
of 10 cm (4 in) to each other and at a height C of 3.8
cm (1.5 in) above the work surface. The side distance
A for limiting the work opening must be 10 cm (4 in).
Position of the anemometer in the opening:
WINDOW
SEAL
WINDOW
MIDDLE OF
HOT WIRE
HOT WIRE
ANEMOMETER
PLANE OF
MEASUREMENT