Hi,
With all the talk about High Pressure cartridges (Myself included) along with the new cartridge case manufacturing processes paired with harder case alloys, etc etc I figured it might be time worthy for people to get a better look at how pressures are measured from what is considered to most modern and high tech testing facility in the USA (NTS).
I am working with them in regards to a couple of Hoplite Arms projects...specifically to find the pressure destruction point of our receivers and finding destruction point of some new cartridge designs/alloys.
Here is a reference guide as to how they do pressure sensors along with below information from our meeting yesterday:
For SAAMI pressure testing, a conformal sensor (conformal, in that the face of the sensor is curved to match the contour of the cartridge being measured) is used to measure the pressure near the mid-point of the cartridge. The sensor is a piezoelectric transducer; we use this coupled with a voltage peak meter to measure the pressure during each firing event. The pressure is measured to the single psi unit for most tests.
There are variations from cartridge to cartridge as you pointed out. SAAMI attempts to negate these variations in 2 ways:
Theis
Edited To Add: I tried putting this guide into the resources section of SH but got error of file too large.
With all the talk about High Pressure cartridges (Myself included) along with the new cartridge case manufacturing processes paired with harder case alloys, etc etc I figured it might be time worthy for people to get a better look at how pressures are measured from what is considered to most modern and high tech testing facility in the USA (NTS).
I am working with them in regards to a couple of Hoplite Arms projects...specifically to find the pressure destruction point of our receivers and finding destruction point of some new cartridge designs/alloys.
Here is a reference guide as to how they do pressure sensors along with below information from our meeting yesterday:
For SAAMI pressure testing, a conformal sensor (conformal, in that the face of the sensor is curved to match the contour of the cartridge being measured) is used to measure the pressure near the mid-point of the cartridge. The sensor is a piezoelectric transducer; we use this coupled with a voltage peak meter to measure the pressure during each firing event. The pressure is measured to the single psi unit for most tests.
There are variations from cartridge to cartridge as you pointed out. SAAMI attempts to negate these variations in 2 ways:
- Each time a new lot of brass is introduced to the testing process, the transducer is calibrated with that brass using an oil calibration system. This allows the transducer to be ‘calibrated’ for each unique lot of brass that is used.
- At the start of each test day, SAAMI requires that reference ammunition be fired, of the same type being tested that day. This allows for corrections to be made to the velocity/pressure measurements that are actually obtained, and are based on published ‘nominal’ values that are periodically released by SAAMI, for each caliber.
Theis
Edited To Add: I tried putting this guide into the resources section of SH but got error of file too large.
