Dynamic Pressure Sensor Instruction Manual

Dynamic Pressure Sensor Instruction Manual

Summarize

Our company is a domestic enterprise specializing in the research, development and production of dynamic pressure sensors. Due to the good characteristics of piezoelectric pressure sensors, they are used as a preferred product for explosion testing at home and abroad. Our pressure sensors are suitable for mechanics, explosion, blasting, fluid mechanics, hydraulics, rock geotechnics, protection and civil engineering. Pressure sensor has a fast rise time, small size, wide frequency response (low to zero frequency, high to the intrinsic frequency), good temperature characteristics, good dynamic performance, good linearity (small range, high range when the sensitivity is similar), low drift, high reliability, reusable, good long-term stability, good sealing, can be applied to different ranges, frequency response, the environment of the test field. The sensor body is laser welded and has good sealing performance, and the shell is made of high-strength materials.

1.General Dynamic Pressure Sensor

Dynamic pressure sensor after years of continuous improvement, the series of products derived from dozens of models, the resonant frequency is also greatly increased, amplitude-frequency characteristics indicators have been greatly improved.

The sensor uses piezoelectric quartz material as the sensitive element, due to the piezoelectric dynamic pressure sensor has a fast rise time, small size, wide frequency response, good temperature characteristics, good linearity (small range, high range when the sensitivity is similar), low drift, high reliability, reusability, long-term stability, sealing is good, good environmental adaptability, at the same time, with its small size, good amplitude-frequency characteristics, so that it is in the domestic and foreign Dynamic test and explosion test as a preferred product.

2.Sensor specifications

3. Sensor selection

1,IEPE-type and charge-type sensor selection

Piezoelectric pressure sensor IEPE type and charge type two, IEPE type built-in amplifier circuit, easy to use, cost-effective, but its shortcomings are easier to damage than the charge type sensors, another shortcoming is that because of its output voltage limitations, the test range (dynamic range) is not flexible. Charge type with charge amplifier, has a larger dynamic range, the user can be based on the above, combined with their own needs to choose.

2, Select the appropriate resonant frequency of the sensor

Explosive pressure test of high frequency, which requires the sensor itself resonance frequency should be high enough to avoid resonance sensor, when used, the resonance frequency of the selected sensor should be higher than the test of the explosion frequency, if the sensor's resonance frequency is not enough, the useful signal will be amplified by the resonance, can not read the true amplitude of the explosion wave, the impact of the test signal is accurate. Figure 1 below is the standard explosion waveform, Figure 2 is the sensor resonance frequency is not enough to produce the waveform resonance phenomenon.

4.Installation and use, supporting instruments, self-test maintenance

1,installation

Dynamic pressure sensors for a wide range of applications, such as artillery, internal combustion engine cylinder pressure, engine, safety and security engineering facilities, the sensor is also installed in many ways, such as pressure sensors pressure-sensing surface can be directly to the source of the explosion, or was 90 ° (swept) installation. The sensor itself has a thread, can be screwed into the test device, can also be clamped.

Tooling should have a certain degree of rigidity, installation should be both rigid and flexible, the sensor installation can be used with their own threads, sealed with copper sealing ring, copper is a good sealing material, has excellent flexibility. If the installation needs, the above sensors can be clamped installation, in order to reduce the clamping stiffness generated by the resonance and reduce the vibration sensitivity, can be used in the clamping part of the thickness of about 1mm rubber isolation. In the sealing ring should be replaced in time depending on the wear and tear. Sensor installation torque of about 20Nm.

According to the test requirements, the user can adopt suitable installation methods, such as the application of explosion-proof wall test, the pressure sensor can be mounted on the wall, the pressure-sensing surface should be flush with the wall.

2,System one point grounding

Pressure transducers can be used as reflective waveform overpressure test, many products come with threads for easy installation, when installed, the sensitive surface of the sensor should be flush with the mounting member. The transducer can also be mounted using a clamping method, where the clamping area is insulated with an insulating material such as rubber skin, which helps to improve the waveform quality and at the same time achieves a point of grounding. Some users will be adapted through the mounting block, we recommend that, in the case of a small explosion equivalent can be used to insulate the material, can be vibration-resistant and insulated.

Our free-field sensor mounting bracket in the clamping part of the insulating material as a liner and screw fastening, can also realize a point of grounding. As the free-field sensor mounting support bar has a certain height, from the ground plug to the connection part should have a certain strength, to avoid shaking and other factors brought about by the interference.

The installation and test waveform improvement discussed above are interrelated, and it is up to the user to keep figuring it out and improving their installation skills.

3,Matching Instruments

(1), in the explosion field, the amplifier is used to connect the sensor and the signal analyzer, it is crucial to choose the amplifier with the right frequency, otherwise, it will greatly affect the test accuracy. Be careful, the instrument frequency response is best about two times the test frequency (because the nominal frequency of the instrument is -3dB), so that the most realistic restoration of the entire explosion waveform state. Charge-type sensors connected to the charge amplifier, IEPE sensors connected to the broadband constant current adapter, the use and calculation can refer to the relevant instruction manual, the pressure value calculation mainly refers to the follow-up instrument manual.

(2), data collector (signal analyzer)

Collector is mainly used for high-frequency pressure sensors on the explosion, blast shock wave testing and analysis. Can be composed of distributed explosion test system, can be used for a wide range of explosion testing. Multi-channel combination, each channel 20M sampling rate.

In order to ensure accurate testing, the recommended sampling frequency of the data collector should be > 10 times the test frequency.

4, the elimination of transient high temperature

The transient high temperature of the explosion will make the piezoelectric pressure sensor test waveform with nominal polarity of the opposite jump, domestic and foreign general-purpose pressure sensors have this phenomenon, seriously affecting the signal interpretation. It is recommended that the near field in the pressure sensor sensitive surface coated with petroleum jelly, epoxy glue to eliminate transient high temperature effects.

5,Resonance frequency elimination

When the test signal produces resonance, you can use the low-pass filter of the data collector to filter out the noise and take out the useful signal.

6, high-frequency testing and the relationship between current

It is recommended to use as high a current as possible within the nominal value for high frequency testing.

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