Common faults and remedies for pressure measuring instruments
Abstract: The measurement and control of pressure is very important in the automation of industrial production. Accurately measuring and controlling pressure is essential to ensure product quality and production safety. Pressure measurement has attracted more and more attention. Therefore, it is important for us to accurately grasp the failure of pressure measurement instruments and eliminate them effectively.
Various pressure gauges are used in industrial production processes, and the main technical performance of various pressure measuring instruments are listed in the table.
How elastic gauges work
The elastic pressure gauge is a kind of pressure measuring instrument with a large quantity and a wide range. Its working principle is the use of spring tubes, diaphragms, bellows, and bellows as elastic elements. Under the action of the measured medium, corresponding displacements are generated. The transmission mechanism drives the pointer and indicates the measured pressure value on the dial.
Common faults and troubleshooting
The pointer is not at zero, on a scale of the dial
The pressure gauge is pressurized and the pressure value is found to change proportionally from a certain scale. The main reason for this phenomenon is that the pressure gauge is usually used in a place where the vibration is relatively large, or the pressure gauge is inadvertently thrown and makes pressure. In the zero-return process, the momentary failure of meshing between the sector gear and the center axis eliminates this failure by removing the needle and repositioning the needle.
As the pressure increases, the spring tube pressure gauge gradually increases or gradually decreases.
The above error is called linear error, and the main reason is that the transmission ratio has changed. As long as the position of the adjustment screw is moved and the transmission ratio is changed, the error can be adjusted to the allowable range. When the inspected table error is positive, and gradually increases with the increase of pressure, the adjustment screw will be moved outwards to reduce the transmission ratio; when the error of the inspected table is negative, and gradually decreases as the pressure increases. Hours, move the adjustment screw inward to increase the gear ratio.
Nonlinear error
The indication error of the pressure gauge varies disproportionately with the increase in pressure. This error is called nonlinear error. The main reason for this phenomenon is that pressure gauges have been used for a long period of time and the coordination between components has changed. The way to eliminate this kind of fault is to change the angle between the sector gear and the tie rod.
The hand walks fast in the first half, slowly in the second half, and adjusts the angle between the pull rod and the sector gear.
The pointer walks slowly in the first half and goes faster in the second half, increasing the angle between the drawbar and the sector gear.
Adjusting the angle between the pull rod and the sector gear can be achieved by rotating the movement. The specific method is to loosen the floor fixing screws and rotate the movement to a suitable position, then tighten the bottom fixing screws and pressurize the new calibration. The adjustment method is determined according to the specific conditions of the error. Normally, the nonlinear error of the instrument is first adjusted to a linear error, and then the linear error is adjusted. For this reason, in general, adjusting the angle between the pull rod and the sector gear also adjusts the position of the adjustment screw.
Hairsprings
Hairspring tangling is caused by human damage caused by overload or severe impact or self-demolition. When it is in the normal position, it gives the center gear a counterclockwise linear and stable restoring force. If the hairspring is twisted, this restoring force will disappear, and (1) the handspring will swing, the value will be unstable, and it will increase. Occasional error. (2) Large zero error. (3) Systematic errors increase. The method to eliminate this kind of failure: (1) Heavy-duty spring (2) with hairspring
Gear teeth and mating shaft hole corners are worn out
Caused by the numerical error is large and unstable, there are stuck phenomenon. The main reason for this damage is that the pressure gauge is caused by prolonged use under a fixed and unstable load (such as a powered air compressor). Therefore, there is a large amount of compensation or glitches in the pressure transmission process, which makes the measurement value excessive. :
Remedy: (1) replace the new accessories (2) to take shrinkage repair, damage to the tooth can be adjusted to avoid damage to the tooth surface to continue to use.
The pointer does not return to zero
If the pressure is relieved after being boosted, the pointer will not return to zero, indicating that the zero state of this watch increases the force in the direction of restoring force. This force comes from the frictional resistance or the residual tension of the deformation. Frictional resistance mainly occurs in the hairspring and the hinge meshing part. If the hairspring is tacked or twisted, the linkage hinge does not move, and the meshed parts have burrs, which will increase the friction rapidly and make the pointer back to zero. Returning these parts to a normal state eliminates the non-zeroing phenomenon.
Conclusion: This is the common failure of the spring tube pressure and how to eliminate it.
Through continuous learning and practice, we have mastered the verification and repair work of pressure gauges (precision pressure gauges), and eliminated various faults of spring tube pressure gauges in a timely manner, laying the foundation for the normal operation of the company.
Abstract: The measurement and control of pressure is very important in the automation of industrial production. Accurately measuring and controlling pressure is essential to ensure product quality and production safety. Pressure measurement has attracted more and more attention. Therefore, it is important for us to accurately grasp the failure of pressure measurement instruments and eliminate them effectively.
Various pressure gauges are used in industrial production processes, and the main technical performance of various pressure measuring instruments are listed in the table.
meter
name
Measuring range
Accuracy
Advantages and disadvantages
The main purpose
Hydraulic pressure gauge
0-15 0-2000
mmH2O or mmHg
(0.02-1.5) level
Simple structure, easy to use, but narrow measuring range, can only measure low pressure and micro pressure
Used to measure low pressure and vacuum, or as a standard pressure gauge
Piston pressure gauge
-0.1-0.25Mpa
0.1-250MPa
(0.02-0.05) level
High measurement accuracy, but complex structure and high price
Used to certify precision pressure gauges
Elastic pressure gauge
-1-10000 MPa
(0.25-2.5) level
Wide range of use, wide measuring range, simple structure, cheap price, electrical contact type, remote transmission type, etc.
Used to measure pressure and vacuum, local indication, centralized control or record, send alarm
Electric pressure gauge
0.7-5×102MPa
(0.2-1.5) level
According to the principle of signal conversion potentiometer type, strain type, Hall type, inductive type, vibration frequency type, etc.
Mostly used for remote transmission of pressure signals, signaling and centralized control, suitable for forming automatic control systems, combined with computers
How elastic gauges work
The elastic pressure gauge is a kind of pressure measuring instrument with a large quantity and a wide range. Its working principle is the use of spring tubes, diaphragms, bellows, and bellows as elastic elements. Under the action of the measured medium, corresponding displacements are generated. The transmission mechanism drives the pointer and indicates the measured pressure value on the dial.
Common faults and troubleshooting
The pointer is not at zero, on a scale of the dial
The pressure gauge is pressurized and the pressure value is found to change proportionally from a certain scale. The main reason for this phenomenon is that the pressure gauge is usually used in a place where the vibration is relatively large, or the pressure gauge is inadvertently thrown and makes pressure. In the zero-return process, the momentary failure of meshing between the sector gear and the center axis eliminates this failure by removing the needle and repositioning the needle.
As the pressure increases, the spring tube pressure gauge gradually increases or gradually decreases.
The above error is called linear error, and the main reason is that the transmission ratio has changed. As long as the position of the adjustment screw is moved and the transmission ratio is changed, the error can be adjusted to the allowable range. When the inspected table error is positive, and gradually increases with the increase of pressure, the adjustment screw will be moved outwards to reduce the transmission ratio; when the error of the inspected table is negative, and gradually decreases as the pressure increases. Hours, move the adjustment screw inward to increase the gear ratio.
Nonlinear error
The indication error of the pressure gauge varies disproportionately with the increase in pressure. This error is called nonlinear error. The main reason for this phenomenon is that pressure gauges have been used for a long period of time and the coordination between components has changed. The way to eliminate this kind of fault is to change the angle between the sector gear and the tie rod.
The hand walks fast in the first half, slowly in the second half, and adjusts the angle between the pull rod and the sector gear.
The pointer walks slowly in the first half and goes faster in the second half, increasing the angle between the drawbar and the sector gear.
Adjusting the angle between the pull rod and the sector gear can be achieved by rotating the movement. The specific method is to loosen the floor fixing screws and rotate the movement to a suitable position, then tighten the bottom fixing screws and pressurize the new calibration. The adjustment method is determined according to the specific conditions of the error. Normally, the nonlinear error of the instrument is first adjusted to a linear error, and then the linear error is adjusted. For this reason, in general, adjusting the angle between the pull rod and the sector gear also adjusts the position of the adjustment screw.
Hairsprings
Hairspring tangling is caused by human damage caused by overload or severe impact or self-demolition. When it is in the normal position, it gives the center gear a counterclockwise linear and stable restoring force. If the hairspring is twisted, this restoring force will disappear, and (1) the handspring will swing, the value will be unstable, and it will increase. Occasional error. (2) Large zero error. (3) Systematic errors increase. The method to eliminate this kind of failure: (1) Heavy-duty spring (2) with hairspring
Gear teeth and mating shaft hole corners are worn out
Caused by the numerical error is large and unstable, there are stuck phenomenon. The main reason for this damage is that the pressure gauge is caused by prolonged use under a fixed and unstable load (such as a powered air compressor). Therefore, there is a large amount of compensation or glitches in the pressure transmission process, which makes the measurement value excessive. :
Remedy: (1) replace the new accessories (2) to take shrinkage repair, damage to the tooth can be adjusted to avoid damage to the tooth surface to continue to use.
The pointer does not return to zero
If the pressure is relieved after being boosted, the pointer will not return to zero, indicating that the zero state of this watch increases the force in the direction of restoring force. This force comes from the frictional resistance or the residual tension of the deformation. Frictional resistance mainly occurs in the hairspring and the hinge meshing part. If the hairspring is tacked or twisted, the linkage hinge does not move, and the meshed parts have burrs, which will increase the friction rapidly and make the pointer back to zero. Returning these parts to a normal state eliminates the non-zeroing phenomenon.
Conclusion: This is the common failure of the spring tube pressure and how to eliminate it.
Through continuous learning and practice, we have mastered the verification and repair work of pressure gauges (precision pressure gauges), and eliminated various faults of spring tube pressure gauges in a timely manner, laying the foundation for the normal operation of the company.
Henan Zonghai Plastic Industry Co., Ltd. , https://www.hnzonghai.com