ASTM E128-99 (2019) PDF

Full title and description

Standard Test Method for Maximum Pore Diameter and Permeability of Rigid Porous Filters for Laboratory Use — designation E128 − 99 (reapproved 2019). This test method defines a uniform procedure (bubble‑point/air‑pressure technique and air‑flow permeability measurement) for determining the maximum pore diameter and permeability of rigid porous laboratory filters (sintered glass, ceramic, metal, or plastic).

Abstract

This standard describes two complementary measurements: (1) maximum pore diameter determined by wetting the filter with a specified test liquid and applying increasing air pressure until the first dynamic bubble passes through (bubble‑point principle), and (2) permeability measured as the air flow through the filter under a defined pressure differential. Results are reported in SI units; the method is intended for laboratory quality control, comparison, and tracking changes during use.

General information

• Status: Active — reapproved (historical standard reapproval).
• Publication date: Reapproved November 1, 2019 (original designation E128‑99 first approved 1999).
• Publisher: ASTM International (formerly American Society for Testing and Materials).
• ICS / categories: 71.040.20 (Laboratory ware and related apparatus).
• Edition / version: E128 − 99 (Reapproved 2019) — often shown as E0128‑99R19 (current reapproval).
• Number of pages: 4 pages (concise test method).

Scope

This test method covers determination of maximum pore diameter and permeability for rigid porous filters used in the laboratory for filtration or diffusion. It applies to filters manufactured from sintered glass, ceramic, metal, or plastic, and establishes a uniform designation for maximum pore diameter as well as a means to detect changes in pore structure with use. Values are stated in SI units.

Key topics and requirements

• Bubble‑point (maximum pore diameter) measurement: wetting with specified test liquid and controlled air pressure until first dynamic bubble appears; calculation uses test‑liquid surface tension and applied pressure.
• Permeability measurement: air flow through the filter measured under a defined pressure differential and reported per unit area.
• Apparatus and procedural notes: describes typical apparatus arrangements, manometer/pressure control, and sample immersion practices; the standard does not prescribe one fixed fixture because of varying filter shapes.
• Units and reporting: SI units required; recommended test liquids and conversion relationships given in the method.
• Significance: intended for quality control, comparison of filters, and detection of pore changes due to processing or use.

Typical use and users

Laboratory technicians, quality control engineers, filter manufacturers, materials researchers, and regulatory/compliance personnel use this method to: verify filter pore specification, compare lots or types of rigid porous filters, evaluate effects of manufacturing or post‑processing (e.g., coating, autoclaving), and monitor performance changes over time.

Related standards

Standards and test methods that reference or complement E128 include membrane filter pore‑size methods such as ASTM F316 (bubble point and mean flow pore tests) and other ASTM practices referenced in the text (for example D845 as a historical referenced document); users often consult related membrane and filtration standards when selecting test liquids or extending to membrane materials.

Keywords

maximum pore diameter, bubble point, permeability, rigid porous filters, sintered glass, ceramic filter, metal filter, plastic filter, laboratory test method, ASTM E128.

FAQ

Q: What is this standard?

A: ASTM E128‑99 (Reapproved 2019) is a short ASTM test method that specifies how to determine the maximum pore diameter (by the bubble‑point/air‑pressure technique) and the air permeability of rigid porous laboratory filters.

Q: What does it cover?

A: It covers filters used for laboratory filtration or diffusion made from sintered glass, ceramic, metal, or plastic; it describes the bubble‑point procedure for maximum pore diameter and a method to measure air permeability under a pressure differential, with results reported in SI units.

Q: Who typically uses it?

A: Laboratories, filter manufacturers, QA/QC personnel, and researchers working with rigid porous filters use this method to certify filter pore performance, compare products, and detect changes after processing or use.

Q: Is it current or superseded?

A: The document is a historical designation originally approved in 1999 and reapproved in 2019 (E128‑99R19); the reapproval date is November 1, 2019, and the reapproved version remains the active/recent reapproval of this method. Users should check ASTM’s catalog for any subsequent revisions after 2019.

Q: Is it part of a series?

A: E128 is a stand‑alone test method within ASTM Committee E41 (Laboratory Apparatus); related pore‑size and membrane test methods (for different material classes or smaller pore ranges) appear in other ASTM designations such as F316.

Q: What are the key keywords?

A: Maximum pore diameter, bubble point, permeability, rigid porous filters, sintered glass, laboratory test method, ASTM E128.