ASTM D2389-83(1994)
(Test Method)Standard Test Method for Minimum Pressure for Vapor Phase Ignition of Monopropellents (Withdrawn 2003)
Standard Test Method for Minimum Pressure for Vapor Phase Ignition of Monopropellents (Withdrawn 2003)
SCOPE
1.1 This test method covers the determination of the minimum pressure at which a monopropellant ignites in the vapor phase.
1.2 This standard should be used to measure and describe the properties of materials , products , or assemblies in response to heat and flame under controlled laboratory conditions and should not be used to describe or appraise the fire hazard or fire risk of materials , products , or assemblies under actual fire conditions. However , results of this test may be used as elements of a fire risk assessment which takes into account all of the factors which are pertinent to an assessment of the fire hazard of a particular end use.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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Designation: D 2389 – 83 (Reapproved 1994)
Standard Test Method for
Minimum Pressure for Vapor Phase Ignition of
Monopropellents
This standard is issued under the fixed designation D 2389; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope apparatus. (However, it is important to realize the limitations
set on interpreting such information.)
1.1 This test method covers the determination of the
minimum pressure at which a monopropellant ignites in the
3. Significance and Use
vapor phase.
3.1 In vapor-air mixtures the minimum spark-ignition en-
1.2 This standard should be used to measure and describe
ergy has been very helpful in evaluating fuels, both for
the properties of materials, products, or assemblies in response
performance and for handling characteristics. The technique
to heat and flame under controlled laboratory conditions and
reported herein is useful for evaluating a similar characteristic
should not be used to describe or appraise the fire hazard or
for monopropellants in the vapor phase. For monopropellants
fire risk of materials, products, or assemblies under actual fire
that ignite easily at normal pressure, that is, very close to 1 atm,
conditions. However, results of this test may be used as
the usual minimum spark-ignition energy techniques can be
elements of a fire risk assessment which takes into account all
employed. It has been found, however, that most useful
of the factors which are pertinent to an assessment of the fire
monopropellants will not ignite in the vapor phase at a pressure
hazard of a particular end use.
of 1 atm. At the higher pressures necessary to obtain ignition,
1.3 This standard does not purport to address all of the
experimental difficulties are experienced with electric spark.
safety concerns, if any, associated with its use. It is the
For example, the high voltages required to jump the spark gap
responsibility of the user of this standard to establish appro-
are difficult to handle in this type of system.
priate safety and health practices and determine the applica-
3.2 A technique has, therefore, been partially developed to
bility of regulatory limitations prior to use.
determine the minimum pressure for vapor-phase ignition. This
2. Summary of Test Method technique involves the electrical fusion of small wires. In
practice the experimental evaluation of energy is somewhat
2.1 The minimum pressure for vapor-phase ignition is a
difficult; however, a useful quantity, the minimum pressure at
limiting measure of what is conceived to be a fundamental
which ignition can be obtained with a fixed energy, can be
monopropellant property, the minimum ignition energy. The
readily determined. The significance of this quantity can be
minimum pressure for vapor-phase ignition is that pressure
better understood by reference to Fig. 1 where the minimum
below which it is impossible to ignite a monopropellant vapor
spark-ignition energy for n-pentane-air is plotted as a function
with a fixed quantity of energy applied in a well-defined
of the total pressure. This curve, which is representative of all
manner. It is expected that, by employing greater quantities of
the air-fuel mixtures studied, is employed because no compa-
energy or applying them in somewhat different fashions,
rable data are available for monopropellants. The monopropel-
ignition may be obtained at lower pressures. However, the
lants already studied behave in the same manner. For acetylene
quantity obtained using the procedure described in Section 5
at 100°C and 0.07 J, a minimum pressure of 3.5 atm was
gives useful relative values which are for most practical
obtained in a small 38-mm diameter cylindrical bomb, and 2.2
purposes a minimum pressure for vapor-phase ignition. The
atm in a larger 76-mm diameter spherical bomb. Instead of
principal advantage of this test is the small quantity (only a few
obtaining a curve similar to that shown in Fig. 1, which would
millilitres) of sample required, the simple apparatus in which
be desirable, only one point was obtained, namely the pressure
the experiment can be performed, and the versatility of the
at a fixed ignition energy. The temperature is always a variable
and must be specified.
This test method is under the jurisdiction of ASTM Committee F-7 on
Aerospace Industry Methods and is the direct responsibility of Subcommittee
4. Apparatus
F07.02 on Propellant Technology.
Current edition approved April 29, 1983. Published August 1983. Originally 4.1 Fig. 2 shows a schematic drawing of the apparatus used
published as D 2389 – 65T. Last previous edition D 2389 – 70 (1980).
for determining the ignition pressure limits of vapors by fused
This method is identical in substance with the JAANAF method “Minimum
wires (Note 1) at any temperature from 25 to 260 °C. The
Pressure for Vapor Phase Ignition,” Test No. 2, Liquid Propellant Test Methods,
apparatus shall consist of: (1) a thermostat-equipped stainless-
December 1959, and published by the Chemical Propulsion Information Agency,
Johns Hopkins University, Applied Physics Laboratory, Johns Hopkins Rd., Laurel,
steel bomb into which the monopropellant vapor is placed, (2)
MD 20707.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 2389
3 3
cm (liner in) and 45 cm (liner out) to permit testing small
quantities of fuel. The over-all internal volume, including leads
and pressure transmitter (Fig. 5 and Fig. 6) shall be 98 cm .
The stainless steel removable liner also permits sampling and
weighing of residual solids left after an explosion. The bomb
shall be electrically heated and capable of being regulated from
ambient temperature to 260°C by a thermoswitch. In the
temperature range from 25 to 260°C, sufficiently high pres-
sures can be obtained with most of the higher-molecular-
weight compounds to determine the minimum pressures for
vapor-phase ignition. The sample shall be introduced in the gas
phase from a conventionally heated manifold for handling
organic vapors; fuels with less than adequate vapor pressure
shall be introduced as liquids by means of a syringe-type
injector through hypodermic tubing, the tubing size being
determined by the physical properties of the liquid fuel.
4.1.2 Bomb Head and Liner—The bomb head (Fig. 4) shall
be made of Type 316 stainless steel with an outside diameter of
7 15
1 ⁄8 in. (47.6 mm) at the top and a depth of ⁄16in. (23.8 mm)
not including the wire holder posts. The wire holders (Note 2)
shall be made of Type 316 stainless steel tubing, the outer tube
having a ⁄8-in. (3.2-mm) outside diameter, the inner tube, a
⁄32-in. (2.4-mm) outside diameter. The outer tube shall be
slotted to permit movement of the inner tube by means of a
small stainless steel guide rod, which is driven through the
inner tube. A stainless steel piano wire spring shall provide the
FIG. 1 Effect of Pressure on Minimum Spark-Ignition Energy of
Pentane necessary tension to hold the fuse wire. Since good electrical
contact is essential, it is advisable to have the tension on the
spring as great as possible without breaking the fuse wire. This
a means of holding the small wires, ( 3) a means of removing
shall be determined by screwing an extra long spring on the
carbonaceous material formed in explosive decomposition
holder post and backing off until it no longer breaks the fuse
(many of the substances which have been evaluated by this
wire. The positive wire terminal shall be connected to the
technique have been acetylenic compounds which give large
external electrical circuit by means of an insulating terminal
quantities of carbonaceous residue), and (4) an electric-current
which is insulated further by PTFE gaskets. The hypodermic
supply. In the present apparatus, the wire-fusion time is
tubing shall be brought through the bomb head and sealed with
determined by the voltage applied to the wire and the charac-
a PTFE gasket by means of a brass packing nut. The bomb liner
teristics of the fuse wire.
(or cup) and the bomb head shall be threaded for easy
NOTE 1—All measurements have been made with Nichrome V wires, 3
attachment. The bomb head shall be provided with a handle to
mm long. A diameter of 0.0635 mm (2.5 mil) was found to be most
facilitate removing from the bomb (Fig. 7). A brass locking
satisfactory. Smaller wires (0.024 mm in diameter) gave inconsistent
ring, equipped with lugs, shall seal the bomb head to the bomb.
results, and larger wires (0.10 mm in diameter) caused welding of the wire
A ⁄16-in. (1.6-mm) PTFE gasket shall be used as the sealing
ends to the wire clamps.
agent. A wrench shall be used to secure the bomb head to the
4.1.1 Bomb —The ignition bomb (Figs. 3 and 4) shall be
bomb.
made of Type 316 stainless steel having an outside diameter of
1 1
4 ⁄8 in. (104.8 mm) and an inside diameter of 1 ⁄2 in. (38.1
NOTE 2—The wire holders shall be spring-loaded, and the wire
mm). The outside height shall be 4 in. (102 mm) and the inside threaded through small holes in each post. The spring holds a plunger
firmly against the wire so that good electrical contact is made. It becomes
chamber height with liner removed shall be 1 ⁄8in (41.3 mm).
1 necessary when carbonaceous products are formed to clean the holes and
Drill a ⁄2-in. (12.7-mm) observation hole into the bottom of the
the plunger face each time a new wire is threaded.
1 1
bomb. This hole shall be sealed with a ⁄4 by 1 ⁄8-in. (6.4 by
28.6-mm) outside diameter borosilicate glass window, polytet-
4.1.3 Spool, Head, and Cup Holders—The wire spool
rafluoroethylene (PTFE) gaskets, and a brass lock ring. There
holder, head holder, and cup holder (Fig. 8) are not necessary,
shall be three ⁄8-in. gas inlet valves with PTFE packing. The
but they are convenient tools for speeding up the operation.
fourth outlet shall be connected to the pressure transmitter (Fig.
The spool holder shall consist simply of a ⁄2-in. (12.7-mm)
5). The bomb shall be designed with an internal volume of 25
aluminum rod on which the spool can freely roll. The fuse wire
shall be threaded through two pieces of foam rubber mounted
on a ⁄2-in. (12.7-mm) rod to keep the wire from unwinding.
Detailed drawings of the ignition bomb are available from the American
The thermostated cup holder (Fig. 8) shall retain the cup for
Institute of Aeronautics and Astronautics, 1290 Avenue of the Americas, New York,
easy assembly and maintain the cup at the operating tempera-
N.Y. 10019. Request Supplement I of American Rocket Society Recommended Test
No. 2. ture. The head holder shall provide a means for keeping the
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 2389
FIG. 2 Fuse-Wire-Ignition Apparatus
head at the operating temperature and shall hold the head for Many fuels tend to polymerize in the tube at the point of
easy threading of the wire. contact with the bomb.
4.1.4 Pressure-Measuring System—The pressure-measuring 4.1.5.1 Rather than attempt to clean the tip of the injector
system shall include a bellows-type pressure transmitter (Fig. 5 tube, it is more expedient to pull the tube through and break off
and Fig. 6) used to isolate the pressure gages from the the end after first nicking it with a file. The tubing shall be
temperature of the bomb, a means for flushing the transmitter, made longer than the dimensions of the bomb dictate. It is
four pressure transducer strain gages covering the range from always advisable to check the tubing before reassembling the
0 to 1000 psia (0 to 6.9 MN/m absolute), a voltmeter, a bomb head to make sure that the tubing is unrestricted. If the
silicone oil reservoir, approximately ⁄2 pt (235 cm ) of silicone flow is partially restricted, one or two shots will plug the tubing
oil, a regulation transformer, and the necessary resistors to again. Another trouble spot is the valve seating spring on the
provide regulation of the input to the gages. The control circuit injector. The tension on this spring must be slightly greater
diagram is shown in Fig. 9. Fig. 2 shows the position of each than that supplied in the pipetting outfit in order to seal the
component in the pressure-measuring system. It is imperative bomb during evacuation. With fuels that have low boiling
that all points in the hydraulic system be below the oil reservoir points (less than 75°C) it is imperative that the injector be
so that there will be no air bubbles trapped in the lines. The placed far enough away from the bomb assembly so that heat
system must be evacuated before filling with oil in order to from the bomb does not vaporize the fuel in the injector
give consistent pressure measurements. Frequent calibration of assembly. Bubbles in the syringe, valve, or tubing between the
the strain gages is necessary because it is suspected that the fuel reservoir and injector will cause the injector to become
silicone oil jells after prolonged exposure to the high tempera- inoperative.
tures in the bellows assembly, thus causing an expansion in the 4.1.6 Ignition System—The ignition system shall consist of
hydraulic system. a0to10-V, ten-turn potentiometer-rheostat, a heavy-duty
4.1.5 Liquid-Fuel Injector—The liquid-fuel-injection sys- electrical switch, nine 6-V batteries connected to a rotary tap
tem shall consist of a continuous pipetting outfit with inter- switch to enable one to obtain the desired voltage, the
changeable syringes of ⁄2, 1, and 2.0-cm capacities. The necessary electrical leads, and the wire holders. The positive
rubber check valves have been replaced with similar valves of terminal shall be connected by means of a banana plug
stainless steel using ⁄16-in. (1.6-mm) O-rings (compatible with soldered to the fusinite terminal. The ground terminal shall be
propellant) for sealing. (The rubber valves proved to be connected to the bomb head handle by means of a heavy-duty
unsatisfactory because of swelling and cracking and because of battery clip.
their inability to withstand the high pressures generated in the 4.1.7 Vacuum System—A glass cold trap (dry ice and
bomb and those necessary to inject the liquid fuels.) The rubber acetone bath) shall be located in the vacuum line leading to the
tubing that is suppl
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