Popularize differential pressure switch common problems and daily maintenance knowledge

Differential pressure switches are not only suitable for refrigerants with fluorinated hydrocarbons but also for air and liquids (permissible liquid temperatures are -40 to 135°C). The differential pressure switch uses the pressure difference between the two pipes to send an electric signal. When the pressure difference between the two ends of the series pipe rises (or falls) and exceeds the set value of the controller, a signal is sent to control the reversing valve for reversing or monitoring the lubrication. system. The valve is then opened large (or closed), so that the pressure difference between the two ends of the system liquid tube is reduced to achieve the normal operation of the system.
Differential pressure switch notes:
1. If the installation of the differential pressure switch does not follow the above instructions and the two ports are down, the switch point detection pressure difference will deviate by 20Pa, which is mainly caused by pressure
The principle of differential switch is decided (differential pressure switch has a very thin film to divide the interior into two chambers, if the film is not installed vertically but water
Flat installation, the film's own weight will affect the gas pressure differential detection).
2. Avoid electric shock or damage to the device. Make sure the power switch is off when removing the cover.
3. The wire connection should be completed and the connection status checked before use. Incorrect connection may cause permanent damage to this device.
4. In the case of low current (0.1A or less), when the voltage is less than 30V, it is recommended to connect an RC network to the circuit.
5. The mounting hole of the plastic pipe should be matched before use, and the “Z-shaped” bracket should be installed on site (standard configuration).
6. Ensure that the vibration of the assembly surface is minimal or no vibration. The switch can be directly fixed on the pipe, heater or panel.
7. Positions of pressure connections: + (high pressure) and - (low pressure or static pressure)
Differential pressure switch FAQ:
1, after temporary use. Can not be strictly closed, a large amount of internal leakage; X-type pressure switch due to internal leakage is particularly large, the pressure measurement can not be carried out.
2. The dirt in the oil will be the pressure difference switch and pressure orifice of the pressure gauge (usually φ0.8 ~ 1.0mm plugging. The pressure gauge pointer will produce a large beat, dull phenomenon, affecting the accuracy of the measurement value. Detachable pressure gauge for cleaning, use φ0.5mm steel and pay attention to the cleanliness of the oil, the wire through the orifice, the pressure of each measurement point sealed by the gap, when the valve core and the valve body hole with a larger gap.
3, pressure switch using rotary valve type. Or with the groove on the surface, when measuring the pressure, there will be no serious phenomenon of each series of cavity, resulting in inaccurate pressure measurement. At this time, if the valve core is brushed or re-aligned, the valve hole should be ground. Make sure the fit clearance is in the range of 0007~0.015mm.
4. To adjust the damper (the front end of the valve plug is conical throttling) when the adjustment is too large. Can cause the gauge pointer to swing, the measured pressure value is not accurate, and the watch moves slowly. In this case, the damper opening should be adjusted appropriately. The cone can be corrected on the cylindrical grinding machine.
5. The position of the pressure gauge is not correct. It was found that a pressure gauge was installed at the remote control hole of the relief valve. There is residual air in the Bourdon tube of the gauge. The pressure jump of the gauge is inevitable. The phenomenon of pressure gauge disappeared immediately. Refit in other places where the pump pressure can be measured.
6, differential pressure switch because the valve core and valve hole with a large gap or seal and wear pits. It also causes a large amount of pressure oil to be drained to the oil discharge port, so that the pressure measured by the pressure gauge is different from the actual pressure value of the actual measurement point, and it is even impossible to perform multi-point measurement. At this point reconfigure the valve plug or replace the pressure switch. Measuring at several points is a stress.
7. The differential pressure switch positioning steel ball is not ejected. When the valve core is rotated, the rotated position does not allow the oil hole of the pressure point to be measured, so that the oil at the pressure measurement point cannot enter the pressure through the straight groove on the valve core. In the table, the pressure test will not be allowed.
8. When the spool is turned into the second pressure measurement point, the measured pressure is inaccurate. The pressure switch should be used correctly as described above.

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