Common faults and solutions for customized nitrogen vacuum furnaces

The common faults and solutions for customized nitrogen vacuum furnaces are as follows:

Abnormal temperature
High temperature alarm
Reason: Abnormal temperature controller parameters in the work area; The output terminal of the solid-state relay in the corresponding work area is broken down; Poor contact of thermocouple probe.
Solution: Check if the temperature controller parameters in the workspace are normal, and refer to other temperature controllers in normal use to calibrate all parameters; After a power outage, use a multimeter to measure the resistance between the two output points of the solid-state relay. Normally, the resistance should be several megohms or more. If it is broken down, replace it with a new one of the same model; When the power is turned on, gently shake the thermocouple probe in the corresponding working area by hand. If the corresponding temperature controller shows a large jumping amplitude, it indicates poor contact of the thermocouple probe and needs to be replaced with a new one.
The displayed temperature is too low to reach the set value
Reason: The parameters of the temperature controller in the work area are abnormal or there is no output signal; The thermocouple in the corresponding work area is damaged; The heating tube is not functioning properly when powered on.
Solution: Check if the parameters of the temperature controller in the work area are normal and if there is an output signal; Swap the thermocouple in the corresponding work area with the thermocouple on the normal thermostat and observe the temperature display. If the thermocouple is indeed damaged, it must be replaced; After powering on and starting up, start heating. According to the circuit diagram, directly use a test pen to test the wires connected to the heating tube in the corresponding working area (the white high-temperature wire on the solid-state output terminal is the one) to see if there is electricity. If there is electricity arriving, it is necessary to use a clamp meter to measure whether the current is different from other working areas. Under normal circumstances, the difference is not significant. If there is no electricity arriving, the circuit must be checked one by one according to the circuit diagram to see where the electricity is cut off and whether any components are burned out.

Vacuum anomaly
Vacuum cannot be drawn up or is too low
Reason: Abnormal vacuum gas source or compressed air pressure; Vacuum gauge malfunction; The door is not tightly closed or the sealing film is damaged or deformed, and there are foreign objects on the door panel; There are leaks in the pipelines, pneumatic valves, thermocouple entrances, and other locations corresponding to the work area.
Solution: Confirm whether the vacuum gas source is normal (above -95KPa) and whether the compressed air pressure is normal (normal usage range is 0.4-0.6 MPa); Check if the vacuum gauge is in good condition, compare it with a vacuum gauge in normal use, and see if the parameters are normal; Check if the door is tightly closed, if the sealing film at the entrance is damaged or deformed, and if there are any foreign objects on the door panel; If there is no problem with the door, it is necessary to check the corresponding work area’s pipelines, pneumatic valves, thermocouple entry points, and other locations. Usually, there are more situations at the thermocouple entry point because if the thermocouple is replaced, it often damages the vacuum sealing performance and must be re sealed with AB glue.
Pneumatic valve cannot operate
Reason: The corresponding solenoid valve cannot work properly, and the compressed air pressure does not meet the working requirements; The pneumatic valve itself is damaged.
Solution: First, check if the corresponding solenoid valve is working properly and if the compressed air pressure meets the working requirements. If the air pressure is normal and the solenoid valve is also in good condition, it must be that the pneumatic valve itself is broken and must be replaced with a new one.

Vacuum pump malfunction
low vacuum
Reason: pump oil pollution, insufficient or too thin; The exhaust filter is clogged; There is a leak; Wear or rupture of vacuum pump coupling; Wear of rotary blades; Vacuum pump oil leakage; Loose oil window; The vacuum pump has a large amount of oil fume; The return valve is blocked.
Solution: Clean the vacuum pump and replace it with new vacuum pump oil; Clean or replace the exhaust filter; After evacuating, turn off the power and check for any air leaks in the solenoid valve, pipe joints, vacuum pump suction valve, and sealing gasket around the working chamber; Replace the vacuum pump coupling; Replace the rotary blade; Clean the oil return valve; After draining the oil, remove the oil window and wrap it with raw material tape or thin plastic film; Clean or replace the exhaust filter; Clean the return valve.
Vacuum pump fuel injection
Reason: The O-ring of the suction valve has come off.
Solution: Remove the vacuum tube from the pump nozzle, remove the suction nozzle, take out the compression spring and suction valve, gently stretch the O-ring several times, re insert it into the groove, and then install it.

Abnormal instrument reading
Domestic vacuum gauge reading issues
Reason: The readings of domestic vacuum gauges are based on segmented linear interpolation of the original logarithmic relationship, which can cause one segment to pass and one segment to fail when testing the pressure rise rate; The effective measurement value of the resistance gauge used in vacuum gauges is 0.1-2500Pa. Domestic instruments need to be adjusted to full and zero before each use. If not adjusted properly, the original change of only 0.1Pa may become a change of 1Pa.
Solution: If there are several measuring instruments on the device, they can be compared with each other. The microphone is an absolute vacuum gauge with a measurement range of 0.1-500Pa, which can be used to calibrate the electronic vacuum gauge.
Inaccurate display of vacuum volume in foreign countries
Reason: It can generally be reset under atmospheric pressure to solve the problem.
Solution: Reset under atmospheric pressure.