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SEMI F62-0701 © SEMI 2001 2 5.3.14 V io — outlet isolation valve 6 Significan ce and Use 6.1 T his test m et hod def ines a pro c e dure for testing components being considered for installatio n in a gas distribution sys…
SEMI F62-0701 © SEMI 20011
SEMI F62-0701
TEST METHOD FOR DETERMINING MASS FLOW CONTROLLER
PERFORMANCE CHARACTERISITICS FROM AMBIENT AND GAS
TEMPERATURE EFFECTS
This specification was technically approved by the Global Facilities Committee and is the direct
responsibility of the North American Facilities Committee. Current edition approved by the North American
Facilities Committee on March 22, 2001. Initially available at www.semi.org May 2001; to be published July
2001.
1 Purpose
1.1 The purpose of this document is to define a
method for testing MFCs being considered for
installation into a gas distribution system and to
quantify ambient and gas temperature effects on the
MFC's indicated and actual flow.
2 Scope
2.1 This test method applies to metal and polymer
sealed MFCs with flow rates up to 30 slpm. The tests
include those listed below and are to be performed in
the following order:
1. Ambient Temperature Effects (Steady State and
Transient)
2. Gas Temperature Effects (Steady State and
Transient)
2.2 This standard does not purport to address safety
issues, if any, associated with its use. It is the
responsibility of the users of this standard to establish
appropriate safety health practices and determine the
applicability or regulatory limitations prior to use.
3 Limitations
3.1 This method evaluates mass flow controllers in
typically encountered, realistic operating conditions.
3.2 This test method does not address operational
influences outside of the manufacturer's published
limitations.
4 Referenced Standards
4.1 None.
5 Terminology
5.1 Acronyms and Abbreviations
5.1.1 DUT — device under test
5.1.2 g — gravity
5.1.3 kPa — kiloPascal
5.1.4 MFC — mass flow controller
5.1.5 NIST — National Institute of Standard Tech-
nologies
5.1.6 sccm — standard cubic centimeters per minute
5.1.7 slpm — standard liters per minute
5.2 Definitions
5.2.1 stability, long term — reading ± 2% for over one
hour.
5.2.2 stability, short term — reading ± 2% within five
minutes.
5.2.3 zero setpoint — manufacturer's setpoint for no
flow from the MFC.
5.3 Descriptions of Terms
5.3.1 MFC
1
— inlet mass flow controller.
5.3.2 T
a
— the temperature in the environmental
control chamber.
5.3.3 T
g
— gas temperature at the inlet to the DUT.
5.3.4 T
max
— maximum manufacturer-rated temper-
ature for an MFC.
5.3.5 T
min
— 20°C or manufacturer rated minimum
temperature, whichever is greater.
5.3.6 TC
g
— temperature coefficient due to changing
gas temperature of DUT.
5.3.7 TC
e
— temperature coefficient due to changing
environmental temperature of DUT.
5.3.8 Q
a
— for the purpose of this method, the output
value of the flow standard in units of mass flow.
5.3.9 Q
ind
— for the purpose of this method, the output
value of the device under test in units of mass flow.
5.3.10 Q
sp
— for the purpose of this method, the
intended output in mass flow units for a particular
setpoint.
5.3.11 V
a
— valve A
5.3.12 V
b
— valve B
5.3.13 V
I i
— inlet isolation valve
SEMI F62-0701 © SEMI 2001 2
5.3.14 V
io
— outlet isolation valve
6 Significance and Use
6.1 This test method defines a procedure for testing
components being considered for installation in a gas
distribution system. Application of this method is
expected to yield data allowing an end user to choose
among components tested for the purpose of
qualification for this installation.
7 Apparatus
7.1 See Figures 1a and 1b for schematics of the set-
ups.
7.2 Flow Measurement Device, National Institute of
Standard Technologies (NIST) traceable and capable of
measuring steady-state and transient flow
characteristics, preferably with differential pressure
sensors across a flow restriction. This device should
have a relative accuracy of at least 2 to 1 with respect to
the DUT.
7.3 Temperature Measurement Device, to measure test
gas temperature, NIST traceable and capable of real-
time measurement, with a low mass (< 0.05 g) sensor
and with low thermal losses through the leads (< 0.3
mW/°C).
7.4 Pressure Measurement Device, to measure test gas
pressure, NIST traceable, and capable of real-time
measurement to measure test gas pressure.
7.5 Gas Pressure Control Regulators, to maintain test
gas pressure at 275 kPa ± 5 kPa.
7.6 Gas Temperature Control, heat exchangers and
heaters to maintain the gas temperature equal to the test
temperature within ± 1 °C at the test flow rates.
7.7 Environmental Chamber, capable of stable
temperature control (± 1°C) from at least T
min
to a point
exceeding the maximum rated MFC temperature by
10°C.
8 Reagents and Materials
8.1 Test Gas, clean, dry nitrogen.
8.2 Tubing, cleaned and maintained to have no adverse
effects on the test.
8.3 Valves, capable of unimpaired operation at 100°C.
9 Safety Precautions
9.1 All manufacturers’ recommendations should be
followed and noted when testing the unit. Any safety
precautions should always be followed.
9.2 This standard does not purport to address all of the
safety problems, if any associated with its use. It is the
responsibility of the user to establish appropriate safety
and health practices and to determine the applicability
of regulatory limitations before using this method.
10 Technical Precautions
10.1 The flow standard may read a non-zero value due
to heating of the gas in the test to determine transient
effects on the zero. These readings should be noted.
11 Preparation of Apparatus
11.1 Setup and Schematic, (see Figure 1a) Ambient
Temperature Effects
11.1.1 Install an ambient temperature sensing device
within 5–10 centimeters horizontally adjacent to the
MFC body. The probe should not be in contact with the
MFC body or the environmental chamber walls.
11.1.2 Position the gas temperature sensor in the
center of the gas stream no more than 10 cm upstream
from the inlet surface of the MFC body.
11.1.3 After installation of the MFC, flow nitrogen at
a 100% setpoint to purge the system for a sufficient
time to remove atmospheric contamination.
11.1.4 If the MFC has a selectable Auto Zero function,
note this on all data presentation documents before
proceeding with the test.
11.1.5 Minimize the length of tubing between the
heater and the device under test to reduce gas
temperature changes.
11.2 Setup and Schematic, (see Figure 1b) Gas
Temperature Effects
11.2.1 Install a base temperature sensing device, T
e
adjacent to the MFC body. The probe should be in
contact with the MFC body.
11.2.2 Install an ambient temperature sensing device
within 5–10 centimeters horizontally adjacent to the
MFC body. The probe should not be in contact with the
MFC body or the environmental chamber walls.
11.2.3 Position the gas temperature sensor in the
center of the gas stream no more than 10 cm upstream
from the inlet surface of the MFC body.
11.2.4 After installation of the MFC, flow nitrogen at
a 100% setpoint to purge the system for a sufficient
time to remove atmospheric contamination.
11.2.5 If the MFC has a selectable Auto Zero function,
note this on all data presentation documents before
proceeding with the test.
SEMI F62-0701 © SEMI 20013
12 Calibration and Standardization
12.1 The flow standard, temperature standards, and
pressure standards used are to be NIST traceable.
12.2 All ancillary equipment must be calibrated and
maintained to the manufacturer's recommendations.
Current calibration records must be maintained.
13 Conditioning
13.1 Reference conditions as listed in Appendix 1 are
to be maintained unless otherwise noted.
14 Procedure
14.1 Environmental Temperature Effect
14.1.1 Install the test specimen in the test set-up
according to the manufacturer's recommendations, see
Figure 1a.
14.1.2 Set the environmental chamber temperature
(T
e
) to T
min
and allow it to stabilize for one hour.
Ensure that gas temperature (T
g
) and ambient
temperature (T
e
) are within 2°C of each other before
beginning data collection.
14.1.3 Close V
ii
and V
io
, and record the MFC Q
ind
at a
zero setpoint.
14.1.4 Open V
ii
and V
io
. Change the MFC flow
setpoints to 25%, 50%, 75%, and 100% of full rated
scale.
NOTE 1: T
g
and T
e
must be within 2°C of each other.
14.1.5 At each setpoint, record T
g
, Q
in d
once, and a
minimum of 10 values at a maximum of five second
intervals of T
e
and Q
a
for at least 60 seconds. Record
the average of the 10 values as shown in Table 3.
14.1.6 Repeat Section 14.1.3.
14.1.7 Maintain the setpoint at zero and change the
environmental chamber temperature T
em
to the next
level indicated in Figure 2.
14.1.8 Record the Q
ind
at the zero setpoint in real time
(max 30-second intervals) as the temperature T
e
is
changing. See example of data collection shown in
Table 4.
14.1.9 Allow temperature T
e
to stabilize for a
minimum of one hour.
NOTE 2: The time for the T
e
to stabilize at each level should
be increased to two hours if the indicated flow at T
e
level 1
and 9, or 2 and 8, or 3 and 7, or 4 and 6 are not within 5% of
each other. See Figure 2.
14.1.10 Open the isolation valves V
ii
and V
io
.
14.1.11 Repeat Sections 14.1.3–14.1.9 for each T
e
level, as shown in Figure 2.
14.2 Gas Temperature Effect
14.2.1 Install the test specimen in the test set-up
according to the manufacturer's recommendations, see
Figure 1b.
14.2.2 Allow the system to stabilize for one hour. See
Figure 1. Refer to Figure 4 for flow chart.
14.2.3 Set the heater temperature to raise the gas
temperature, T
g
, such that T
g
is elevated 10°C above
ambient.
14.2.4 Simultaneously open V
ii
and close V
io
.
Continue to monitor T
g
, T
e
, indicated flow, and actual
flow for one hour. If after one hour, the actual flow or
T
g
has not achieved long-term stability, or if T
g
is not
equal to T
e
+ 10 (±2°C), continue until these conditions
are met or until an additional one hour period has
elapsed. If long-term stability is not achieved, note this
occurrence and record the average value of 10 samples
minimum taken at maximum five-second intervals for
each of T
g
, T
e
, indicated flow, and actual flow as shown
in Table 5, for at least 60 seconds.
NOTE 3: If T
g
is not 10°C above ambient return to 14.2.3
and adjust the temperature.
14.2.5 Repeat 14.2.3–14.2.4 until all required setpoints
have been run.
15 Calculations or Interpretation of Results
15.1 Calculations
15.1.1 The measured values for Q
ind
, Q
a
, and T
g
are
determined by an arithmetic average of samples taken
at time intervals after stability has been achieved at
each temperature and flow condition.
15.1.2 The ambient temperature coefficient of flow
shall be calculated as follows:
100 x
)1
T
- 2
T
( x
Q
1
Q
- 2
Q
= C)(%/
TC
ee
sp
aa
e
°
where Q
a1
and Q
a2
are the actual flow rates measured at
ambient temperatures T
e1
and T
e2
respectively. For zero
setpoint use the following.
100 x
)1
T
- 2
T
( x
Q
1
Q
- 2
Q
=
TC
gg
fullscale
aa
zero
This yields a result expressed as a percent of reading
per °C. See example of data collection and analysis
shown in Table 3. Final TC
e
is to be presented in Table
2 format.