Heraeus HS 12, Руководство по обслуживанию, Страница: 76 / 282

Service Instructions HERAsafe HS/12/18
Valid: 05.2001 / 50060091 / A
• 47 •
B Field tests
B5 Inflow velocity test
DIM Method
Install the measuring device and perform the test
measurements:
1. The cabinet must not be switched off as the mea-
surement requires a lead time of twenty minutes.
2. Move the front window into the normal operating
position of 19,9 cm (7,85 inches) access opening
height.
3. Seal DIM adaptor skirting in access opening ma-
king sure no air bypasses measuring device.
4. Evaluate the individual measurements* and cal-
culate the average value of inflow air volume rate
R
1
:
5. Calculate the inflow velocity V
1
as the quotient of
the inflow air volume rate and normal access ope-
ning area:
* If required, correct DIM readings to local density
in accordance with instrument manufacture’s in-
struction.
Anemometer Method
Install the measuring device and perform the test
measurement:
1. The cabinet must not be switched off as the
measurement requires a lead-time of 20 minutes.
2. Move the front window into the measuring position
by lowering to a 7.6 cm (2,99 inches) opening
height.
3. Place the measuring probe tip of the anemometer
on the first measuring point.
4. Perform the measurements from one end of the
work opening to the other.
5. Evaluate the individual measurements* and cal-
culate the average value of the inflow velocity V
1
:
*correct anemometer readings to local density in
accordance with instrument manufacturer’s
instruction.
Nominal values:
Type B3 and Type AB3: 0.53 m/s (105 fpm) DIM
0,58 m/s (115 fpm) Anemom.
Acceptance according to NSF, 49, Annex F:
The average value must be within ± 0.025 m/s
(5 fpm) of the nominal value (e.g. from 115 fpm).
6. Calculate the inflow air volume rate in m³/s (cfm).
The inflow air volume rate is the product of the
average value of the inflow velocity and the actual
area of the constricted access opening.
V x A
2
= R
2
7. Calculate the final inflow velocity V
2
(window at
normal operating height) as the quotient of the in-
flow air volume rate and access opening area:
Nominal values (DIM):
HS 12 Type A/B3: 460 m
3
/h (271 ft³/min)
inflow/exhaust air volume rate
HS 18 Type A/B3: 690 m
3
/h (406 ft³/min)
inflow/exhaust air volume rate
Nominal values (Anemometer):
HS 12 Type A/B3: 505 m
3
/h (297 ft³/min)
inflow/exhaust air volume rate
HS 18 Type A/B3: 750 m
3
/h (442 ft³/min)
inflow/exhaust air volume rate
Troubleshooting :
Inflow velocity and inflow/exhaust air volume rate
not correct:
 Adjust the blower speed using potentiometer P2
at speed controller.
 Check the voltage of the blower at the terminal
strip.
 Replace the downflow filter and/or the exhaust
filter.
 Check the connected exhaust system for proper
operation.
Average value =
Number of measuring points
Sum of measuring values
Average value =
Number of measuring values
Sum of measuring values
V
2
=
A
3
R
2
V
1
=
A
3
R
1