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SEMI F28-1103 © SEMI 1997, 2003 6 6.3.4 Dynamic Test — This test is to immediately follow the static test. To condu ct the dynamic test, actuate the panel’s final process outlet valve at the rate of 1 cycle/m inute for 6…

SEMI F28-1103 © SEMI 1997, 2003 5

6.3.1.1 The test flow rates stated in the above table are

meant to serve as a general guideline. The actual test

flow rates may vary depending on the maximum panel

flow rate as recommended by the manufacturer. The

maximum test flow rate should be the manufacturer’s

maximum recommended flow rate. If no such

maximum flow rate is recommended by the

manufacturer, the flow rates in the above table should

be used.

6.3.2 Background Test — Ensure that all valves

depicted in Figure 1 are in the closed position. Connect

the spool piece to the purge gas inlet (C-2) and the

isokinetic sampler inlet. Ensure that the spool piece and

proper adapters are in place on the test apparatus. (C-1

should be capped at this time.)

6.3.2.1 Close valve V-3. Adjust the regulator (PCV-2)

until PI-5 indicates the appropriate pressure in Table 1.

Open valve V-3 and use FC-2 to establish the specified

test flow rate listed in Table 1. Measure the static

background count. Background count is established

when the counter has sampled a minimum of 74 SL (3

scf), and the arithmetic average during the last 74 SL (3

scf) of gas sampled is < 71 particles/m

(< 2

particles/scf). At a sample flow rate of 1.23 SLPM

(0.05 scfm), the time required is one hour. Ensure that

the background counts are stable or decreasing. If

background cannot be achieved after 147 SL (6 scf)

have been sampled, there may be a problem with the

counter or test apparatus.

6.3.2.2 Disconnect the spool piece from C-2 and

connect it to C-1. Cap C-2 at this point.

6.3.2.3 Open valve V-1 and close valve V-2. Adjust the

regulator (PCV-1) until PI-2 indicates the appropriate

supply pressure listed in Table 1. Open valves V-1 and

V-2 to establish flow. Using the flow control device

(FC-1) set the appropriate test flow rate listed in Table

1. Measure the static background count. Background

count is established when the counter has sampled a

minimum of 74 SL (3 scf), and the arithmetic average

during the last 74 SL (3 scf) of gas sampled is < 71

particles/m3 (< 2 particles/scf). At a sample flow rate of

1.23 SLPM (0.05 scfm), the time required is one hour.

Ensure that the background counts are stable or

decreasing. If background cannot be achieved after 147

SL (6 scf) have been sampled, there may be a problem

with the counter or test apparatus.

6.3.2.4 Actuate valve V-2 at 1 cycle per minute to

measure the background counts under dynamic test

conditions. Dynamic background count is established

when the counter has sampled a minimum of 74 SL (3

scf), and the arithmetic average during the last 74 SL (3

scf) of gas sampled is < 106 particles/m

(< 3

particles/scf). At a sample flow rate of 1.23 SLPM

(0.05 scfm), the time required is 1 hour. If dynamic

background cannot be achieved after 147 SL (6 scf)

have been sampled, there may be a problem with the

counter or test apparatus.

6.3.3 Static Test — Using the flow control device (FC-

1), decrease the flow rate to 2.5–5.0 SLPM (0.1–0.2

scfm), so that some flow remains in the system while

the test component is installed.

6.3.3.1 Remove the spool piece by first disconnecting

the downstream fitting and then the upstream fitting.

Immediately install the test panel with all of the process

valves in the fully-open position by first connecting the

process gas inlet (C-3) fitting and then the process

outlet fitting. Uncap C-2 and connect it to the purge gas

inlet (C-4) connection of the panel with V-3 in the

closed condition. In order to minimize atmospheric

contamination and prevent the counter from cooling off,

removal of the spool piece and installation of the test

panel should take no longer than 2 minutes. Extreme

care should be taken to minimize contamination of the

test apparatus during this operation. The test panel is to

be removed from its inner bag in the Class 100 test

area. If the process outlet connection of the test panel

has mechanical fittings, these fittings are to be properly

connected. If the process outlet has butt weld tube

stubs, the connection is to be made with clean

compression fittings. Do not permanently crimp any

ferrules onto the tube stubs. Nylon ferrules are

acceptable. The purge gas inlet connection (C-4) should

also be connected at this time. The outlet vent

connection should be capped at this time. If this

connection is not capped by the manufacturer, it should

be covered with Aclar or Nylon 66 squares and taped so

as to insure against contamination by the immediate

environment. If applicable, all pneumatic valves should

be connected using the maximum recommended

actuator pressure as specified by the manufacturer.

6.3.3.2 Adjust the panel’s process regulator to obtain

the appropriate process outlet pressure as indicated in

Table 1. Using the flow control device (FC-1), increase

the flow to obtain the appropriate test flow rate as

indicated in Section 6.3.1.1

6.3.3.3 Turn on the counter and conduct the steady

state test. All of the valves on the process panel are to

be tested in a fully-open position until 74 SL (3 scf) of

gas have been sampled. Cumulative data should be

recorded at one-minute intervals.

NOTE 3: The flow rates in Table 1 represent the maximum

test flow rates. If a more thorough test is desired, the static

portion of the test should be repeated at intervals of 20%,

40%, 60%, and 80% of the full test flow rate. Testing at the

lower flow rates may in some instances be more indicative of

panel performance under actual use conditions.

SEMI F28-1103 © SEMI 1997, 2003 6

6.3.4 Dynamic Test — This test is to immediately

follow the static test. To conduct the dynamic test,

actuate the panel’s final process outlet valve at the rate

of 1 cycle/minute for 60 minutes. Each cycle consists of

having the valve in the open position for 58 seconds

and in the closed position for 2 seconds.

6.3.5 Cylinder Change Test — Close V-2, open V-3

and V-4, and adjust PCV-2 until PI-5 reads 3450 Kpag

(500 psig). Adjust the flow rate and pressure to the

vacuum venturi using FC-3 and PCV-3. The flow rate

and pressure should be set to the manufacturer’s

recommended values. Next perform a simulated

cylinder change purge and evacuation sequence

following the valve sequencing, dwell times, pressure

settings, etc. as specified by the manufacturer.

6.3.6 Final Steady State Test — Close V-4, V-3, and

open V-2. Repeat the step in Section 6.3.3.3.

6.3.7 Unregulated Flow Test (optional) — In some

instances, it may be desirable to test the panel with its

regulator in the fully-open position. Such a test will

give an indication of panel particulate performance

without the additional contribution of particles from an

operating regulator. In this instance, steps 6.3–6.3.5

should be repeated with the regulator in the wide open

condition.

6.4 Data Analysis and Reporting — The following test

conditions are to be reported in the data presentation:

1. Date and time of test

2. Operator

3. Test flow rate

4.Test pressures

5. Panel type, manufacturer, and serial number

6. Particle counter manufacturer, serial number, sample

flow rate, model number, specified particle size

sensitivity, and calibration date

7. Test gas type and dew point

8. A schematic of the test apparatus, including

manufacturer’s and model numbers of all test

apparatus components

9. Calibration dates for all instrumentation.

6.4.1 Data Presentation — Graph the static and

dynamic portions of the test separately as counts/minute

(measured by the counter) versus time, including the

appropriate background (measured with the spool piece

in place) with each. Also graph the entire data set as

counts per minute versus time.

6.4.1.1 Present the entire raw data set in tabular form.

6.4.2 Data Reduction — The statistical analysis is

based on the assumption that the particles generated are

randomly distributed and are statistically independent

of each other. The background counts are independent

of the particle performance of the component. The

particle counts observed from the test include the

counts from the component and the background count.

Let:

average background particle count

average total particle count from test

average particle count generated by the test component

Therefore,

c +

6.4.2.1 A statistical analysis of the data is performed to

determine the mean, standard deviation, and the

standard error for each particle size range.

6.4.2.2 The sample mean, X, or average of the data for

each state is given by:

i= 1

∑

where X

is the observed counts for the state and n is the

number of samples.

6.4.2.3 The sample standard deviation is a measure of

the variability of the data about the mean. The standard

deviation, s, for each state is expressed as:

s =

(Xi − X

)

i=1

∑

n − 1

6.4.2.4 The standard error, Se or standard deviation of

the sampling distribution of the mean for each state is

given below:

Se =

6.4.2.5 The average particle count for the total number

of particles generated, or the sample mean, is an

estimation of the population mean. For a 95%

confidence level, the population mean, µ

, will be

within two standard errors of the sample mean, or:

= X ± 2 Se

6.4.2.6 In order to determine if there is statistical

evidence of the component having an effect on the

observed particle count, a test must be conducted to see

if the actual difference between the average background

count, X

, and the average test count, X

, exceeds two

standard errors in a distribution of differences between

means. The average particle count generated by the test

component, X

, is given by:

c =

t −

6.4.2.7 The standard error in a distribution of

differences between means is expressed as:

= S

+ S

6.4.2.8 The 95% confidence interval of the test

component itself is then determined by:

c ± 2 S

6.4.2.9 If this confidence interval includes 0, then this

implies that there is not strong statistical evidence of

the component having an effect on the observed particle

count. If this interval does not include 0, then this

implies there is strong statistical evidence that the

component does have an effect on the observed particle

count.

6.4.2.10 Present in tabular form the average particle

count and the associated upper and lower confidence

limits (as calculated in Section 6.4.2) for each test state.

In addition, present the background test data separately

as a distinct element.

7 Related Documents

Agarwal, J. K. and Sem, G. J., “Continuous Flow,

Single Particle Counting Condensation Nucleus

Counter”, Journal of Aerosol Science, v.11.4. July

1950: 343–357

Fissan, H. and Schwientek, “Sampling and Transport of

Aerosols”, TSI Journal of Particle Instrumentation,

v.2.2. July–December 1987: 3–10

Hinds, W. C. Aerosol Technology: “Properties,

Behavior, and Measurement of Airborne Particles”,

John Wiley & Sons. 1982: 187–194

VanSlooten, R. A., “Statistical Treatment of Particle

Counts in Clean Gases”, Microcontamination, v.4.2.

February 1986: 32–38

ANSI/ASME B46.1

— “Specification for Surface

Texture - Surface Roughness, Waviness, and Lay”

NOTICE: SEMI makes no warranties or

representations as to the suitability of the standards set

forth herein for any particular application. The

determination of the suitability of the standard is solely

the responsibility of the user. Users are cautioned to

refer to manufacturer’s instructions, product labels,

product data sheets, and other relevant literature

respecting any materials mentioned herein. These

standards are subject to change without notice.

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compliance with this standard may require use of

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takes no position respecting the validity of any patent

rights or copyrights asserted in connection with any

item mentioned in this standard. Users of this standard

are expressly advised that determination of any such

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of such rights, are entirely their own responsibility.

2 American Society of Mechanical Engineers, Three Park Avenue,

New York, NY 10016-5990, USA. Telephone: 800.843.2763

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