ASTM D4625 Method for Middle Distillate Fuel Storage Stability at 43°C (110°F)
6. Apparatus
6.1 Sample Containers, borosilicate glass bottles. The containers must have a lid or cover, preferably with a polytetrafluoroethylene (PTFE) insert and a hole for a borosilicate glass vent. The total capacity of the containers is 500 mL.
6.2 Storage Oven, large enough to contain all of the sample bottles. The oven shall be thermostatically controlled to maintain a temperature of 43 ± 1°C (110 ± 2°F). It shall be as dark as possible to prevent degradation due to photolytic reactions and shall also be explosion proof.
6.3 Filter Drying Oven, shall be capable of safely evaporating the solvent at 90 ± 5°C for the drying of filter materials.
6.4 Filtration System - Arrange the following components as shown in Fig. 1.
6.4.1 Funnel and Funnel Base, with filter support for a 47-mm diameter membrane and a locking ring or spring action clip.
6.4.2 Ground/Bond Wire, 0.912 - 2.59 mm (No. 10 - No. 19) bare-stranded, flexible stainless steel or copper installed in the flasks and grounded as shown in Fig. 1.
6.4.3 Receiving Flask, 1.5 L or larger borosilicate glass vacuum filter flask, which the filtration apparatus fits into, equipped with a sidearm to connect to the safety flask.
6.4.4 Safety Flask, 1.5 L or larger borosilicate glass vacuum filter flask equipped with a sidearm to connect the vacuum system. A fuel and solvent resistance rubber hose, through which the grounding wire passes, shall connect the sidearm of the receiving flask to the tube passing through the rubber stopper in the top of the safety flask.
6.4.5 Vacuum System, either a water-aspirated or a mechanical vacuum pump may be used if capable of producing a vacuum of up to 100 kPa below atmospheric pressure when measured at the receiving flask.
7. Reagents and Materials
7.1 Purity of Reagents - Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.
7.2 Nylon Test and Control Membrane Filters - plain, 47-mm diameter, nominal pore size 0.8-µm. (Membrane filters with a grid imprinted on their surface may be used as control membrane filters for identification.)
7.3 Hydrocarbon Solvent, 2,2,4-trimethylpentane (iso-octane) - ASTM knock test reference fuel grade, prefiltered through two glass-fiber filters. (Warning - Extremely flammable. Harmful if inhaled. Vapors may cause flash fire.)
7.4 Adherent Insolubles Solvent (Warning - Extremely flammable. Vapors harmful. May cause flash fire) - Mix equal volumes of reagent grade acetone (Warning - Extremely flammable. Vapors may cause flash fire), methyl alcohol (Warning - Flammable. Vapor harmful. May be fatal or cause blindness if swallowed or inhaled. Cannot be made nonpoisonous), and toluene (Warning - Flammable. Vapor harmful.).
7.5 Purity of Water - Unless otherwise indicated, references to water mean reagent water as defined by Type III of Specification D1193.
7.6 Liquid or Powder Detergent, water-soluble, for cleaning glassware.
8. Sampling Procedure
8.1 Samples for testing shall be obtained by an appropriate method outlined in Practice D4057 or D4177. Sample containers should be 1 gal (3.78 L) or larger, epoxy-lined cans. Fill sample cans almost to the top to avoid a significant air space. Purge the void space with nitrogen. Store the samples at reduced temperature, -7 to 4°C (20 to 40°F), prior to use, where possible.
