Brooks, Mf series – Brooks Instrument Mfi Series User Manual
Page 60
4-22
Brooks
®
Mf Series
Section 4 Maintenance &
Troubleshooting
Installation and Operation Manual
X-TMF-Mfi-Mfx-MFC-eng
Part Number: 541B074AAG
August, 2009
4-6 Restrictor Sizing
The restrictor assembly is a ranging device for the sensor portion of of the
controller/meter. It creates a pressure drop which is linear with flow rate.
This diverts a sample quantity of the process gas flow through the
sensor.Each restrictor maintains the rate of sensor flow to the restrictor
flow, however, the total flow through each restrictor is different. Different
restrictors (micron porosity and active area) have different pressure drops
and produce instruments with different full scale flow rates. For a
discussion of the interaction of the various parts of the instruments, you are
urged to review Section 3-1, Theory of Operation.
If the restrictor assembly has been contaminated with foreign matter, the
pressure drop vs. flow characteristics will be altered and it must be cleaned
or replaced. It may also be necessary to replace the restrictor assembly
when the mass flow instrument is to be calibrated to a new flow rate.
Table 4-6 Model Mf50/60 Series Standard Restrictors
Range
sccm Air Equivalent Flow
Part Number
Size
Low
High
ACLFE
Wire Mesh
D
8.022
11.36
S110Z275BMT
E
11.23
15.90
S110Z276BMT
F
15.72
22.26
S110Z277BMT
G
22.01
31.17
S110Z278BMT
H
30.82
43.64
S110Z279BMT
J
43.14
61.09
S110Z280BMT
K
60.40
85.53
S110Z281BMT
L
84.56
119.7
S110Z282BMT
M
118.4
167.6
S110Z283BMT
N
165.7
234.7
S110Z284BMT
P
232.0
328.6
S110Z285BMT
Q
324.8
460.0
S110Z286BMT
R
454.8
644.0
S110Z287BMT
S
636.7
901.6
S110Z288BMT
T
891.4
1262
S110Z289BMT
U
1248
1767
S110Z290BMT
V
1747
2474
S110Z291BMT
W
2446
3464
S110Z292BMT
X
3424
4849
S110Z319BMA
Y
4794
6789
S110Z321BMA
1
6711
9504
S110Z317BMA
2
9396
13310
S110Z228BMA
3
13150
18630
S110Z226BMA
4
18420
30000
S110Z224BMA
Materials:
BMT = 316 stainless steel (ACLFE only)
BMA = Sintered 316 stainless steel (wire mesh only)
Note: For full scale flow rates less than 8 sccm, use the low flow plug P/N 618K019BMT in place of a restrictor assembly and
install a low flow filler ring P/N 724Z363BMT in the valve cavity after the orifice is installed.