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SEMI F44-0699 © SEMI 1999 1 SEMI F44-0699 GUIDELINE FOR STA NDARDIZATION OF M A CHINED STA I NLESS STEEL WELD FITTINGS This g u ideline was tec hnically approved by the Global Fa cilities Committee and is the direct resp…

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SEMI F43-0699 © SEMI 19999
APPENDIX 1
SAMPLER DESIGN CRITERIA
A-1.1 The average velocity of gas flo wing through the
sampler should approximate the average velocity in the
tubing in which the sampler is inserted. The sample
flow rate used to calculate the sampler diameter is the
total flow drawn by the counter.
A-1.2 Gradual expansion to atmospheric pressure is
recommended for sampling. Critical orifice expansion
may alter the particle level of the sample.
A-1.3 The tip of the sampling probe should have a 30
degree taper on the outside diameter.
A-1.4 The pick-off point should be approximately
centered within the flow stream.
A-1.5 The pick-off point should be approximately 15
diameters of the primary flow tube upstream or
downstream of any connection.
A-1.6 There should be enough volume in the exhaust
portion of the sampler to supply the CNC for one
minute. This volume represents 60 times the volume
that will be drawn by the CNC while the valve is closed
during the dynamic testing. Minimum sample flow
through the CNC is 5 slpm.
A-1.7 State the minimum volume after the probe or
generate a sample blank using the stated volume until
background counts are reached.
Under static flow conditions, the sampler size is within
50% of the size required to achieve isokinetic sampling.
For particles of interest <0.5 um, Hinds
1
and Fissan
2
indicate that any unlikely isokinetic sampling biases are
significant. During dynamic testing, isokinetic
sampling is compromised regardless of the sample tube
size.
D
1
D
2
To
CNC
Isokinetic Sampler Calculation
To establish isokinetic sampling condition:
V
1
= V
2
Q = AV or V = Q/A
so Q
1
/A
1
= Q
2
/A
2
therefore, A
2
= A
1
(Q
2
/Q
1
) or D
2
= D
1
(Q
2
/Q
1
)
1/2
where:
Q = flow rate (volumetric)
A = area (internal cross section)
V = velocity (average)
D = diameter (internal)
subscripts:
1 = main flow line
2 = sample flow line
If pressure correction at point of flow control device is
needed, then:
Q
s
= [(P + 14.7)/14.7]
1/2
x Q
A
where:
Q
A
= actual flow rate
Q
S
= standard flow rate
P = pressure, psig
Temperature variances are assumed to be negligible.
NOTICE: These standards do not purport to address
safety issues, if any, associated with their use. It is the
responsibility of the user of these standards to establish
appropriate safety and health practices and determine
the applicability of regulatory limitations prior to use.
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.
The user’s attention is called to the possibility that
compliance with this standard may require use of
copyrighted material or of an invention covered by
patent rights. By publication of this standard, SEMI
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
patent rights or copyrights, and the risk of infringement
of such rights, are entirely their own responsibility.
Copyright by SEMI® (Semiconductor Equipment and Materials
International), 3081 Zanker Road, San Jose, CA 95134. Reproduction o
f
the contents in whole or in part is forbidden without express written
consent of SEMI.
SEMI F44-0699 © SEMI 19991
SEMI F44-0699
GUIDELINE FOR STANDARDIZATION OF MACHINED STAINLESS
STEEL WELD FITTINGS
This guideline was technically approved by the Global Facilities Committee and is the direct responsibility of
the Japanese Facilities Committee. Current edition approved by the Japanese Regional Standards Committee
on March 17, 1999. Initially available on www.semi.org May 1999; to be published June 1999.
1 Purpose
1.1 The purpose of this guideline is to prevent
confusion among the manufacturers of stainless steel
weld fittings, piping fabricators and end users and to
standardize the dimensions of weld fittings.
2 Scope
2.1 This guideline applies to 6.35 mm (1/4in.), 9.53
mm (3/8in.) and 12.7 mm (1/2in.); the machined
stainless steel weld fittings elbows and tees made for
use in the semiconductor industry.
3 Referenced Documents
3.1 None.
4 Terminology
4.1 elbow weld fittings machined fittings shaped
like the letter "L", for welding tubes in a right angle.
(see Figure 1)
4.2 tee weld fittings machined fittings shaped like
the letter "T", for welding tubes in a T-shape. (see
Figure 2)
4.3 weld fittings machined fittings to be welded or
welded fittings.
Figure 1
Elbow Weld Fittings
Figure 2
Tee Weld Fittings
5 Dimensions of Weld Fittin gs
5.1 Elbow Weld Fittings (see Figures 3A and 3B)
5.2 Tee Weld Fittings (see Figures 4A and 4B)
Figure 3A
Dimensions of Elbow Weld Fittings
NOTE 1: Machined tube weld ends shall be square tolerance ±
0.5°.
NOTE 2: Intersection shall be square tolerance ± 0.5°.
SEMI F44-0699 © SEMI 1999 2
Figure 3B
Dimensions of Elbow Weld Fittings
Figure 4A
Dimensions of Tee Weld Fittings
NOTE 1: Machined tube weld ends shall be square tolerance ±
0.5°.
NOTE 2: Intersection shall be square tolerance ± 0.5°.
Figure 4B
Dimensions of Tee Weld Fittings
6 Marking The Weld Fittings
6.1 Marks include 1), 2), 3), 4), 5), 6) and 7). Marks
1) through 4) shall be made on the weld fittings body.
Marks 5) - 7) shall be made on weld fittings body or its
package (both individual bagging and box).
1) Manufacturer's name
2) Material designator
3) Surface finish designator
4) Heat Number (optional)
5) Lot Number
6) Model (Part Number)
7) Wall thickness of tube end
6.2 To be agreed upon between supplier and user for
marking items and marking locations. The example
below explains marking applications. (see Figures 5A
and 5B)
6.3 Manufacturer's name, Material designator, Surface
finish designator and Heat Number should be marked
on the body. The Heat Number shall be marked either
on the body of the cube along with the other
information, but if space is limited, then the Heat
Number marked on the tube Outside Diameter close to
the body block is permissible.
Figure 5A
Marking Application Example