Small arms ammunition testing is used to set the standard for the highest average peak pressure of the sleeping room, as well as to determine the security of a particular load for the purpose of developing a new load. In metal cartridges, peak pressure may vary based on the used propellant, the primer used, the payload, the projectile type, the depth of the projectile seat, the neck voltage, the throat/litter space parameters. In shotshells, the main factors are heavy load, projectile weight, spindle type, gastric construction, and crimp quality.
Video Small arms ammunition pressure testing
Modern civil testing methodology
Two modern standardized test methodologies used are the Internationale Permanente Commission pour l'Epreuve des Armes ÃÆ' Feu Portatives or C.I.P. methodology, and the Institute of Sporting and Ammunition Weapon Producers or SAAMI methodologies. SAAMI methodology is widely used in the US, while C.I.P. is widely used in Europe especially C.I.P. member countries. While both modern methodologies use piezo pressure transducer sensors to produce pressure readings, differences in test settings mean that the same pressure will often result in very different readings depending on the method used.
Because C.I.P. and the maximum SAAMI pressure is measured differently, it is important to know which methodology is used to measure peak pressure. While C.I.P. pressures are often quoted in megapascals on Wikipedia and bars by C.I.P., and SAAMI in psi, it's not unusual to see C.I.P. the pressure is converted to psi or vice versa.
C.I.P. method
C.I.P. using a case that is drilled to expose the direct pressure transducer to the propellant gas. The piezo gauge (transducer) is positioned at a distance of 25 millimeters (0.98 inches) from the breech face when the cartridge box length allows it, including the limit. When the cartridge cartridge length is too short, pressure measurement will be performed at a specific distance defined by the room shorter than the breech face depending on the dimensions of the casing. The distance specified for a particular room is published in the TDCC data sheet of the chamber In the case of rifle cartridges such as 0.308 Winchester, TDCC M = 25.00 the value indicates the transducer should be positioned at a distance of 25 millimeters (0.98 inches) from the breech face.
In the case of relatively short pistol cartridges such as Parabellum 9ÃÆ' â € "19mm (9mm Luger in C.I.P. nomenclature), TDCC M = 12.50 values ​​indicating the transducer should be positioned at a distance of 12.5 millimeters (0.49 inches) from the breech surface.
Some have incorrectly concluded that C.I.P. measuring the pressure on the mouth of the case to account for variations of SAAMI pressure.
As a C.I.P. transducer almost exclusively using one type of piezoelectric sensor (named "channel sensor") made by the Swiss firm Kistler that requires drilling the cartridge box before firing the inspection cartridge into a specially crafted test tube. Kistler 6215 ballistic measurement sensor has a maximum working pressure of 600Ã, MPa (87,023 psi) and is mounted inside the cartridge case (the surface of the high pressure sensor does not contact the cartridge box) and requires the case of the test cartridge to have holes drilled inside it prior to the test. The test cartridge should be inserted into the chamber in such a way that the hole in the test cartridge box is lined up with the gas port hole supplying the gas pressure from the cartridge carrier to the sensor face. The measurement accuracy of pressure measurement with high-pressure 21st century sensors is expected to be <= 2%.
SAAMI Method
The SAAMI pressure testing protocol uses the Comparador Piezoelectric Quartz Transducer for pressure testing from the fire center revolver and revolver, centerfire weapons, and rimfire bullets. The main source of conformal transducers is the US company PCB Piezotronics. The SAAMI pressure testing protocol uses a test barrel that has a hole located in space in a specific location for the cartridge. SAAMI conformation transformers are mounted into holes that penetrate the test barrel chamber in such a way that the transducer face, the precision machine to match the curvature of the space wall at the site of a certain distance from the breech face, functions as part of the wall of the room. When the cartridge is fired, the gas pressure causes the cartridge box to widen, touching the space wall. The cartridge carrier part that comes into contact with the surface of the conformal transducer provides pressure on the transducer which in turn produces a reinforced minute electronic impulse and results in a reading in pounds per square inch (psi). SAAMI conformation transformers have benefits because they do not require a drilled cartridge box and the challenges associated with the insertion and alignment required from the drilled cartridge box. Instead, it takes a simple pressure test from the case samples from the many cartridge boxes used in the test ammunition. This pressure test determines the required gas pressure to cause the case to expand and come into contact with the surface of the conformal transducer at the time of shooting. These measurements are referred to as "offsets" and make an allowance for "losing" gas pressure before the cartridge case comes in contact with the transducer and generates an impulse. The offset is added to the pressure reading to arrive at the peak pressure reading. Other benefits of SAAMI conformation transducers are: highly adaptive to the demand for high-quality quality control testing of commercial and law enforcement production; transducer protection from direct exposure to high temperature combustion gases and hence long service life; 80,000 psi (551.6 MPa) maximum working pressure. Cartridges with the same wall space diameter at the point of mounting the transducer and operating within a certain space pressure limit can use the same transducer in turn reducing the cost of instrumentation.
Shotshell ammunition method
For shotshell ammunition, technical variations are more easily solved because only one type of piezoelectric sensor (called "tangential sensor") is available from PCB Piezotronics and Kistler International companies for use without drilling without variation between SAAMI and C.I.P guidelines. decision.
External voltage meter
The low cost data collection method uses a resistive tape gauge attached to the outside of the room. The system is usually calibrated to mimic the results of an existing standard system such as the SAAMI system, so the results will be directly proportional. Since this system does not require a special test tube, only firearms that have accessible external space walls are much cheaper.
Maps Small arms ammunition pressure testing
Military test methodology
NATO EPVAT
NATO defines 5.56mm, 7.62mm, 9mm and 12.7mm using the NATO EPVAT testing method, which includes pressure testing. In contrast to civilian testing methods, the NATO EPVAT testing procedure for "NATO wind rifle assemblies" requires pressure sensors or transducers to be mounted in front of the mouth of the case. The advantage of this mounting position is that it is not necessary to drill the cartridge box to install the transducer. Drilling prior to combustion is always a time-consuming process (quick quality control and feedback for production is essential during the ammunition-making process). The disadvantage of this mount is that the pressure rises faster than inside the drilled cartridge box. This causes a high-frequency oscillation of the pressure sensor (approx. 200 kHz for Kistler 6215 transducer) and this requires electronic filtering with the disadvantage that the filtering also affects the lower harmonics in which the peaks are found to cause slight errors in the measurement. This little mistake is not always well controlled and this leads to much discussion of filter sequence, cutoff frequency and type (Bessel or Butterworth). For 9mm NATO EPVAT specified that for 9ÃÆ'â € "19mm Parabellum (9mm Luger in CIP and NATO 9mm nomenclature in NATO nomenclature), the transducer should be positioned in the mid case position (9.5 millimeters (0.37 in)) of the breech surface as instead. CIP 12.5 millimeters (0.49 inches) from the breech face. For NATO EPVAT testing of military weapons, ammunition, NATO designs, EPVAT test barrels with Kistler 6215 channel sensor transducers are used.
US military SCATP
The United States Armed Forces, however, define the test procedure for 5.56mm NATO at SCATP-5.56, 7.62mm NATO at SCATP-7.62, and.45 ACP at SCATP-45. This procedure is based on the SAAMI test methodology.
See also
- Room pressure
- Pressure copper unit
References
External links
- C.I.P. List of TDCC HOMOLOGIES - Tab I - Unframed Cartridge
- C.I.P. List of TDCC HOMOLOGIES - Tab II - Angle cartridge
- C.I.P. List of TDCC HOMOLOGIES - Tab III - Magnum Cartridges
- C.I.P. List of TDCC HOMOLOGIES - Tab IV - Pistol and revolver cartridges
- C.I.P. List of TDCC HOMOLOGATIONS - Tab V - Rimfire - Crusher Cartridges
- C.I.P. List of TDCC HOMOLOGIES - Tab V - Rimfire Cartridges - Transducers
- C.I.P. List of TDCC HOMOLOGATIONS - Tab VI - Cartridges for industrial use
- C.I.P. List of TDCC HOMOLOGIES - Tab VII - Shooting cartridge
- C.I.P. List of TDCC HOMOLOGATIONS - Tab VIII - Cartridges for alarm weapons
- C.I.P. List of TDCC HOMOLOGIES - IX Tab - Dust gun cartridge
- C.I.P. List of TDCC HOMOLOGIES - X Tab - Cartridges for other weapons
- Conformal Sensors Measure Ammunition Pressure Through Casing Shell by Jim Lally and Rod Rhen, PCB Piezotronics, Inc., Sensor Magazine
- Ballistic Pressure Sensor, Synotech Sensor and Messtechnik GmbH
- Firearm Testing: Measuring Room Pressure
Source of the article : Wikipedia
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