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5.1.17 ZAS max  the maximum Zero Attitude Sensitiv ity between two attitud es. 5.1.18 ZAS nm  Zero Attitude Sensitivity b etween attitudes n and m. 5.2 Definitions 5.2.1 actual flow — the flow rate as determined by the…

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SEMI E80-0299 (Reapproved 1104)
TEST METHOD FOR DETERMINING ATTITUDE SENSITIVITY OF MASS
FLOW CONTROLLERS (MOUNTING POSITION)
This test method was technically approved by the Global Gases Committee and is the direct responsibility of
the North American Gases Committee. Current edition approved by the North American Regional Standards
Committee on July 11, 2004. Initially available at www.semi.org September 2004; to be published
November 2004. Originally published in 1999; last published November 2004.
1 Purpose
1.1 The purpose of this test method is to provide a
standardized method for quantifying the effect of
mounting attitude on an MFC.
1.2 This document provides a common basis for
communication between manufacturers and users
regarding testing and describing MFC mounting effects.
2 Scope
2.1 This procedure describes a method to determine the
effect of attitude (mounting position) of a Mass Flow
Controller on flow span and zero.
2.2 The intent of this document is not to suggest any
specific testing program but to specify the test method
to be used when testing for parameters covered by this
method. Reference operating conditions represent the
environmental conditions where the "best" performance
can be expected.
2.3 The minimum test described in this document is to
test one MFC in 5 common mounting positions using
Nitrogen gas at 135.8 kPa (19.7 psia) and 308 kPa (44.7
psia). This test method can be used to evaluate
additional gases, pressures or mounting attitudes.
NOTICE: 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 and health practices and determine
the applicability of regulatory or other limitations prior
to use.
3 Limitations
3.1 It is not practical to evaluate performance under all
possible combinations of operating conditions. This test
procedure should be applied under laboratory
(reference) conditions; its intent is to collect sufficient
data to form a judgment of the field performance of the
MFC being tested.
3.2 The results from this test represent the performance
of the specific device tested i.e., make, model, full scale
flow and operating conditions. The results may not
apply to devices of different manufacture, model, full
scale flow or under different operating conditions.
3.3 Due to manufacturing variability, attitude
sensitivity may vary for the same model of MFC. To
statistically quantify attitude sensitivity for a particular
model of MFC, multiple samples should be tested.
4 Referenced Standards
None.
5 Terminology
5.1 Acronyms and Abbreviations
5.1.1 % F.S. — Percent Full Scale
5.1.2 DUT — Device Under Test
5.1.3 HBD — Horizontal Base Down. Mounting attitude
1, as shown in Figure 1.
5.1.4 HED — Horizontal Either side Down. Mounting
attitude 3, as shown in Figure 1.
5.1.5 HUD — Horizontal Upside Down. Mounting
attitude 5, as shown in Figure 1.
5.1.6 kPa — KiloPascal
5.1.7 MFC — Mass Flow Controller
5.1.8 psia
Pounds per Square Inch Absolute
5.1.9 SAS
max
the maximum Span Attitude
Sensitivity between two attitudes
5.1.10 SAS
nm
Span Attitude Sensitivity between
attitudes n and m
5.1.11 Sccm — Standard cubic centimeters per minute
5.1.12 Slm — Standard liters per minute
5.1.13 VFD — Vertical Flow Down. Mounting attitude
2, as shown in Figure 1.
5.1.14 VFU — Vertical Flow Up. Mounting attitude 4,
as shown in Figure 1.
5.1.15 VID — Vertical Inlet Down. Mounting attitude 4,
as shown in Figure 1.
5.1.16 VIU — Vertical Inlet Up. Mounting attitude 2, as
shown in Figure 1.
SEMI E80-0299 © SEMI 1999, 2004 1
5.1.17 ZAS
max
the maximum Zero Attitude Sensitivity
between two attitudes.
5.1.18 ZAS
nm
Zero Attitude Sensitivity between
attitudes n and m.
5.2 Definitions
5.2.1 actual flow — the flow rate as determined by the
flow standard used in the test procedure.
5.2.2 attitude — the mounting position of the MFC
with respect to the surface of the earth, as shown in
Figure 1.
5.2.3 indicated flow — the flow rate as determined by
the output of the DUT.
5.2.4 measured value — the actual flow through a
DUT, expressed in sccm or slm.
5.2.5 nameplate gas — the gas intended to be
controlled by the MFC in operation.
5.2.6 setpoint — the input signal provided to achieve a
desired flow, reported as sccm, slm, or percent full
scale.
5.2.7 span — the full scale range of the DUT.
5.2.8 zero drift — the undesired change in electrical
output (i.e., indicated flow), at a no-flow condition,
over a specified time period, reported in sccm or slm.
5.2.9 zero offset — the deviation from zero at a “no-
flow” condition reported in sccm, slm, % F.S. or mV.
6 Summary of Test Method
6.1 Gas flow, indicated flow and setpoint data are
collected for an MFC. This data is reduced to quantify
the relationship between the flow control by the MFC
and its relationship to the attitude of the MFC.
6.2 This method allows the user to determine the effect
of different mounting attitudes on MFC zero and span.
6.3 The standard test is determining the effect of
changing between attitudes 1 and 2 on Nitrogen. Other
typical MFC attitudes and gases may also be tested (see
Figure 1).
7 Interferences
7.1 The accuracy rating of the measuring equipment
shall be superior to that of the DUT. Preferably, the
measuring equipment will have an accuracy that is four
times better than the DUT. Calibration equipment must
have a valid calibration certificate.
7.2 Take care when using test instruments with a
specified accuracy expressed in percent of full scale.
7.3 Installation effects on the flow should be
minimized. Monitor pressure upstream of the DUT to
ensure that flow variations due to pressure are
minimized.
7.4 Verify electrical signals directly at the DUT
connector to ensure that the signals at the DUT and
standard agree with the signals at the data recording
equipment.
7.5 All electrical measurements should be read on
devices with at least 4.5 digits of resolution. These
devices must have valid calibration certifications.
7.6
All instrumentation in the test apparatus must
remain in a constant orientation except the device under
test.
8 Significance and Use
8.1 The data generated by this method is used to
estimate the effect-mounting attitude will have on the
performance of a mass flow controller. It would
typically be used to estimate the potential flow error
caused by using an MFC in attitude, other than the one
it was calibrated for.
9 Apparatus (see Figure 2)
9.1 Flow Standard A device or system that
accurately measures the flow and reports the actual
flow.
9.2 Data Acquisition System The system that
measures the electrical signals from the device under
test. The data acquisition system may also read the
signals from the flow standard, record test data and
control the test sequence.
9.3 Isolation Valves Valves that will positively shut
off the gas line.
9.4 Pressure Regulator
A device that regulates gas
pressure to a set value.
9.5 Pressure Transducer An instrument to measure
the gas pressure and report it as an electrical signal.
9.6 Flexible Gas Line Flexible tubing that will
allow the DUT to be moved to the various test attitudes
while the other components can remain in a fixed
position.
10 Materials
10.1 Clean, Dry N
2
, with 99.9% minimum purity.
10.2 MFC Calibration Test Gas as desired.
SEMI E80-0299 © SEMI 1999, 2004 2
11 Safety Precautions
11.1 Follow the manufacturer’s specifications and
instructions for installation and operation whenever
possible. Note any exceptions in the test report.
12 Test Specimen
12.1 Allow all components in the test apparatus to
warm up following the manufacturer’s specification.
12.2 Take necessary steps when switching gases to
ensure that only the desired gas is in the DUT and flow
standard at the time the test is performed.
13 Preparation of Apparatus
13.1 Locate the DUT in the test environment to
stabilize temperature prior to warm up.
13.2 The reference operating conditions shall be as
follows:
13.2.1 Ambient temperature 21 ± 4 C
13.2.2 Ambient Temperature Stability Ambient
temperature to stay constant within ± 1 °C during data
acquisition period.
13.2.3 Gas temperature Same as ambient.
13.2.4 Gas pressure, Outlet Ambient Pressure
13.3 Following the conditioning period (Section 12.1)
warm up the device according to manufacturer's
specifications.
13.4 Perform an adequate purge to ensure all previous
gases and atmospheric moisture has been removed from
the system.
13.5 Leak check the test set up, using available
methodologies to verify the test system leak integrity.
13.6 The power supply must be sufficiently rated for
the device under test.
14 Procedure
14.1 Open V1 and V2. DUT and allow the flow to
stabilize. Adjust the inlet pressure to 135.8 kPa (19.7
psia).
14.2 Close the downstream isolation valve (V2); then
close the upstream isolation valve (V1), (see Figure 2).
14.3 With both isolation valves closed, and a 100%
setpoint wait until the pressure drop across the MFC is
dissipated, ensuring a “no flow” condition through the
MFC. Dissipation of the pressure across the MFC is
indicated when the indicated flow drops to a steady
state value near zero.
14.4 Once the indicated flow has dropped to a steady
value set the MFC setpoint so there is no power being
dissipated by the control valve. For a normally closed
valve this is 0% and for a normally open control valve
it is 100%.
14.5 After the electrical output signal has stabilized for
at least three minutes, record the MFC indicated zero in
Table 1.
14.6 Open V1 and V2, command 100%.
14.7 After the electrical output signal has stabilized for
at least three minutes, record the actual flow as reported
by the flow standard and the indicated flow in Table 1.
14.8 Change the attitude of the DUT to the next
desired attitude.
14.9 Close the downstream isolation valve (V2); then
close the upstream isolation valve (V1) (see Figure 2).
14.10 With both isolation valves closed, and a 100%
setpoint wait until the pressure drop across the MFC is
dissipated, ensuring a “no flow” condition through the
MFC. Dissipation of the pressure across the MFC is
indicated when the indicated flow drops to a steady
state value near zero.
14.11 Once the indicated flow has dropped to a steady
value set the MFC setpoint so there is no power being
dissipated by the control valve. For a normally closed
valve this is 0% and for a normally open control valve
it is 100%.
14.12 After the electrical output signal has stabilized
for at least three minutes, record the MFC indicated
zero in Table 1.
14.13 Open V1 and V2, command 100%.
14.14 After the electrical output signal has stabilized
for at least three minutes, record the actual flow as
reported by the flow standard and the indicated flow in
Table 1.
14.15 Repeat Sections 14.8 to 14.14 for each of the
desired attitudes.
14.16 Return the DUT to attitude 1.
14.17 Adjust the inlet pressure to 308 kPa (44.7 psia).
14.18 Repeat Sections 14.8 to 14.14.
SEMI E80-0299 © SEMI 1999, 2004 3