SEMASPEC Test Method for Determination of Filter Flow Pressure Drop Curves for Gas Distribution System Components

Transcription

1 SEMASPEC Test Method for Determination of Filter Flow Pressure Drop Curves for Gas Distribution System Components Technology Transfer B-STD

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3 SEMASPEC Test Method for Determination of Filter Flow Pressure Drop Curves for Gas Distribution System Components February 22, 1993 Abstract: This SEMASPEC establishes a test method for preparing a flow rate vs. pressure drop curve for filters being considered for installation into a high-purity gas distribution system. Application of this test method is expected to yield comparable data among components tested for the purposes of qualification for installation. This document is in development as an industry standard by Semiconductor Equipment and Materials International. When available, adherence to the SEMI standard is recommended. Keywords: Equipment, Eqipment Performance, Gas Filters, Facilities, Gas Distribution Systems, Specifications, Components, Component Testing, Flow Rates, Pressure Authors: Jeff Riddle Approvals: Jeff Riddle, Project Manager Venu Menon, Program Manager Jackie Marsh, Director of Standards Program Gene Feit, Director, Contamination Free Manufacturing John Pankratz, Director, Technology Transfer Jeanne Cranford, Technical Information Transfer Team Leader

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5 1 SEMASPEC # B-STD SEMASPEC Test Method for Determination of Filter Flow Pressure Drop Curves for Gas Distribution System Components 1. Introduction Semiconductor cleanrooms are serviced by high-purity gas distribution systems. This document presents a test method that may be applied for the evaluation of one or more components considered for use in such systems. 1.1 Purpose The purpose of this document is to define a method for testing components being considered for installation into a high-purity gas distribution system. Application of this test method is expected to yield comparable data among components tested for the purposes of qualification for this installation This document establishes a test method for preparing a flow rate versus pressure drop curve for filters. 1.2 Scope This procedure applies to clean filters including those cartridges of metal, ceramic and membrane construction. The pressure drops for integral housing/cartridge combination units are determined as a single set of values. For housings with removable filter cartridges, the flow curves of the housing and cartridge are determined separately. 1.3 Limitations For separable filtration units, a single cartridge pressure drop value cannot be combined to give the pressure drop value for an extended length cartridge, due to the common outlet port This method is written with the assumption that the operator understands the use of the apparatus at a level equivalent to six months of experience This method is written to test a filter under normal operating conditions. It does not prescribe a procedure for reverse flow testing since operation of the filter in this manner is not recommended by the manufacturers. 2. Reference Documents American Society of Mechanical Engineers Performance Test Code PTC , "Applications." Part II of "Fluid Meters, Interim Supplement on Instruments and Apparatus." 3. Terminology 3.1 CDA clean, dry air. 3.2 filter cartridge the filtration element. 3.3 filter housing the shell that contains the filter cartridge. 3.4 filtration unit fhe assembly consisting of a filter cartridge and housing. Examples are an integral unit, in which the filter cartridge and element are not separable, and a separable unit, in which the filter cartridge and housing can be disassembled.

6 2 3.5 psi pounds per square inch. 3.6 psia pounds per square inch absolute. 3.7 psid pounds per square inch differential. 3.8 psig pounds per square inch gauge. 3.9 scfm standard cubic feet per minute slpm standard liters per minute standard conditions kpa, 0.0 C (14.73 psia, 32 F). 4. Test Protocol 4.1 Test Conditions Precautions This test method may involve hazardous materials, operations, and equipment. This test method does not purport to address the safety considerations associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and determine the applicability of regulatory limitations before using this method Test pressure is to be incremental, up to the maximum rated pressure Test flow rate is to be incremental up to the maximum rated flow, at the maximum rated pressure drop Test temperature is to be maintained between 18 C (64 F) and 26 C (78 F). 4.2 Apparatus Materials Nitrogen or CDA filtered to <0.02 micrometer is required Instrumentation A pressure regulator, a test filter, a downstream flow regulating valve, a flow meter, and several upstream and differential pressure transducers or gauges (0.1 psi sensitivity) are required Instruments shall be calibrated regularly per manufacturer's instructions Setup and Schematic Construct a test stand for the measurement of gas flow rates for known pressure drops across the test filter as shown in the schematic drawing (See Figure 1). Nitrogen gas supply is filtered by an electronics grade high purity point-of-use gas filter before it is delivered to the test filter through a pressure regulator and a throttling valve. The test specimen is isolated between two throttling valves to allow for control of the inlet pressure to the test component. Inlet pressure is measured immediately upstream of the test filter by a pressure gauge. Pressure drop across the test specimen is measured by an electronic differential pressure transducer capable of reading 0.1 kpa across the test device. Flow measurement is carried out downstream of the throttling valve located downstream of the test piece by rotometers.

7 Temperature of the gas is measured at two locations by thermocouples installed downstream of the test piece. The thermocouples are connected to a digital readout unit to directly display and read the filter outlet gas temperature Table 2 gives the piping requirements, standard test section configuration. (Section 5.3) Figure 2 gives the recommended pressure connection to be followed in constructing the test apparatus. (See Section 5.4). 3 Figure 1 Filter Flow Curve Test Schematic

8 4 4.3 Test procedures Integral Filtration Unit Assemble the filtration unit into the test apparatus. (See Figure 1.) Set the inlet pressure using the pressure regulator to 10% of the filter s maximum rated inlet pressure or to 103 kpa (15 psig), whichever is less. Pressure is read on the inlet pressure gauge Adjust the flow rate using the regulating valve to give 10% of the maximum rated flow. Flow rate is read on the flow meter Read and record the inlet temperature, inlet pressure, pressure drop across the filter, ambient temperature, ambient pressure and flow rate corrected for upstream pressure Repeat steps in Sections and at 25%, 50%, 75%, and 100% of the maximum rated flow Repeat steps in Sections through at inlet pressures of 207 kpa (30 psig), 621 kpa (90 psig), and 1379 kpa (200 psig). Also test the filter at higher pressures up to the maximum rated pressure. It is recommended that the filter be tested at pressures of 33%, 67%, and 100% of the filter s maximum pressure rating, with tests being limited by the sensitivity of the differential pressure device Separable Filtration Unit Filter Housing Assemble the filter housing into the test apparatus Set the inlet pressure using pressure regulator to 10% of the housing's maximum rated inlet pressure or to 103 kpa (15 psig), whichever is less. Pressure is read on the inlet pressure gauge Adjust the flow rate using the regulating valve to give 10% of the maximum rated flow. Flow rate is read on the flow meter Read and record the temperature, pressure, pressure drop and flow rate corrected for upstream pressre Repeat steps in Sections and at 25%, 50%, 75%, 100% of the filter cartridge's maximum rated flow Repeat steps in Sections through at inlet pressures of 207 kpa (30 psig), 621 kpa (90 psig), and 1379 kpa (200 psig). Also, it is desirable to test the filter at higher pressures, up to the maximum rated pressure. It is recommended that the filter be tested at pressures of 33%, 67%, and 100% of the filter's maximum pressure rating, with tests being limited by the sensitivity of the differential pressure device.

9 4.3.3 Separable Filtration Unit Assembled Cartridge and Housing Assemble the filter cartridge into the filter housing Assemble the filtration unit into the test apparatus Set the inlet pressure using the pressure regulator to 10% of the filter s maximum rated inlet pressure, or to 103 kpa (15 psig), whichever is less. Pressure is read on the inlet pressure gauge Adjust the flow rate using the regulating valve to give 10% of the maximum rated flow. Flow rate is read on the flow meter Read and record the temperature, pressure, pressure drop, and flow rate Repeat steps in Sections and at 25%, 50%, 75%, and 100% of the maximum rated flow Repeat steps in Sections through at inlet pressures of 207 kpa (30 psig), 621 kpa (90 psig), and 1379 kpa (200 psig). Also, it is desirable to test the filter at higher pressures, up to the maximum rated pressure. It is recommended that the filter be tested at pressures of 33%, 67%, and 100% of the filter's maximum pressure rating, with tests being limited by the sensitivity of the differential pressure device The flow curve for the filter cartridge is determined by subtracting the pressure drop of the housing from the pressure drop of the assembled filtration unit at respective flow rates and test pressures. 4.4 Data Analysis Complete Table 3. (See Section 5.) 5

10 6 5. Illustrations 5.1 See Figure 1 for filter flow test schematic diagram. Table 1 Symbols Used T Temperature (K) degrees Kelvin P Pressure (kpa g) kilopascal, gauge q Flow rate (Nm 3 /hr) normal cubic meters per hour P(H) Differential (kpa d) kilopascal, differential pressure of housing P(T) Differential (kpa d) kilopascal, differential pressure of total P(C) Differential (kpa d) kilopascal, differential pressure of cartridge

11 7 Table 2 Piping Requirements-Standard Test Sections A *, ** B C D Standard Test Section Configuration At least 18 nominal pipe diameters of straight pipe 2 nominal pipe diameters of straight pipe. 6 nominal pipe diameters of straight pipe At least 1 nominal pipe diameter of straight pipe *Dimension A may be reduced to 8 nominal diameters if straightened vanes are used. Design of straightening vanes can be found in ASME Performances Test Code PTC Applications. Part 2 of Fluid Meters, Interim Supplement on Instruments and Apparatus. **If an upstream flow disturbance consists of two ells in series and they are in different planes, dimension A must exceed 18 nominal pipe diameters unless straightened vanes are used. See Section 3.2 for definition of the test specimen. Figure 2 Recommended Pressure Connection 1 1 Reprinted by permission. Copyright Instrument Society of America From ANSI/ISA-S

12 8 Table 3 Filter Flow Pressure Drop Curves (page 1 of 2) Filtration Unit Identification Test Number Date Operator Name Barometric Pressure Pa INTEGRAL FILTRATION UNIT T (K) P (kpa-g) P(T) (kpa-d) Flow Meter Reading (units) q (Nm 3 /hr) 1ST 2ND 3RD ETC

13 9 Table 3 Filter Flow Pressure Drop Curves (page 2 of 2) HOUSING WITH CARTRIDGE INSTALLED T (K) P (kpa-g) P(T) (kpa-d) Flow Meter Reading (units) q (Nm 3 /hr) CARTRIDGE PRESSURE DROP P(CARTRIDGE) = P(T) - P(H) q (Nm 3 /hr) P(T) (kpa-d) P(H) (kpa-d) P(Cartridge) (kpa-d) NOTICE: DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. MAKES NO WARRANTIES AS TO THE SUITABILITY OF THIS METHOD FOR ANY PARTICULAR APPLICATION. THE DETERMINATION OF THE SUITABILITY OF THIS METHOD IS SOLELY THE RESPONSIBILITY OF THE USER.

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