Problems after a machine has been relocated rarely appear on the day itself; most of them show up a few days into the run: more vibration from the machine, leaks at the connections, a vacuum level that will not come up, and alarms that come and go. The reason is that a relocation changes three kinds of condition at the same time, the foundation and the installation state, the connections between the pipework and the wiring, and the sealing surfaces of the vacuum system. The last two necessarily produce new interfaces and new joints during dismantling and reassembly, and what used to be a reliable seal is no longer reliable.
The re-check is carried out in the following order: level and vibration damping → pipe stress and alignment → electrical and earthing → sealing of the vacuum system → safety interlocks and protection operation. The reason for the order is that the first two decide whether the remaining three can work steadily, while the fifth is the safety baseline and is done last as a single operating test.
Item one: level and vibration damping
This machine moves the oil by gravity and carries the condensate out by the negative pressure in the tank. Once the machine stands at an angle the oil collects on one side of the tank, the level detection becomes inaccurate and the condensate is not easy to drain off completely. The check is to place a spirit level on the top of the tank, on the upper surface of the frame and on the base plate in turn, measuring in both the transverse and the longitudinal direction. The criterion is that the readings in every direction fall within the permitted range given in the machine manual; where they differ, level the machine by adjusting the levelling feet instead of packing it with shims. For vibration damping, confirm that there are anti-vibration pads or a resilient support between the feet and the floor, so that the frame does not touch the floor at a rigid point. The criterion is that the machine shows no visible displacement and the pipework does not shake continuously when it runs at full load.
Item two: pipe stress and alignment
When the inlet and outlet oil pipes and the vacuum lines are joined, if the bolts are made to fit by forcing the pipes into position, the bending moment is carried into the flanges and the pump connections, and the sealing surfaces start to leak after a few days of running. The check is: after all the flanges have been tightened, push the pipe sections by hand and check whether they remain under load; use a straightedge to compare whether the centre lines of two pipe sections are offset; check that the directions of the oil inlet and the oil outlet match the connections on the machine. The criterion is that the pipe sections move freely after tightening, that the connections carry no sideways force, and that the pipework does not oscillate periodically once the machine runs. The action is to realign, adding flexible connectors or additional fixed supports where necessary.
Item three: electrical and earthing
A relocation usually means that the distribution circuit has changed as well, and the wiring between the machine and the distribution cabinet has been disconnected and reconnected. The check is: verify the incoming voltage and frequency (three-phase 380V, 50Hz) and check the phase sequence as described in the machine manual; check that the terminals are tight and free from oxidation; measure the insulation with an insulation tester; re-measure the earth resistance with an earth resistance tester and compare it with the record from before the move. The criterion is that the limit for the earth resistance follows the machine manual and the electrical rules of the site, and that the re-measured value does not exceed the value on the earlier record; that the insulation is acceptable; and that the phase-loss and phase-sequence protection operates reliably under simulated conditions. The action is to retighten the terminals and carry out moisture protection, and to repeat the protection test once the phase sequence has been corrected.
Item four: sealing of the vacuum system
This is the item most likely to give trouble after a relocation. Dismantling and reassembly necessarily produce new interfaces, and every new interface is a potential leak point. The check is to draw the system down to a negative pressure first and then apply soapy liquid point by point to all the new flanges, joints, seals and sight glasses; a place where a continuous string of bubbles appears is a leak point, and the positions that were levered or knocked with tools during the move deserve particular attention. The criterion is that with no load the reading settles near the working vacuum of -0.08 MPa; the working vacuum indicator of the ZYD-100 is -0.08 ~ -0.0999 MPa; and that the reading does not recover quickly after the machine has been stopped and left standing. The action is to retighten or replace the seals and to carry out a complete leak check again.
Item five: safety interlocks and protection operation
The overpressure audible and visual alarm and stop, the phase-loss and phase-sequence protection, and the infrared level and foam detection with automatic defoaming all have to be tested again after a relocation. It cannot be assumed that they still work. The check is to disconnect the power and, following the test method in the machine manual, simulate each trigger condition in turn and confirm that both the alarm sound and the lamp operate and that the pump and the heating really are cut off. The criterion is that every condition interlocks reliably, that the alarm indication is correct and that the reset works normally. The action is that if any one of them does not operate, the machine is not put into service.
| Symptom | Possible cause | How to confirm | Action |
|---|---|---|---|
| Clear machine vibration after start-up, with oil weeping from the connections | Uneven feet, missing vibration damping, stress in the pipework | Measure each face with a spirit level, push the pipe sections by hand after tightening | Adjust the feet, fit anti-vibration pads, realign |
| The vacuum level sticks around -0.05 MPa and will not go further | A new interface was not refitted properly, or there is contamination on the sealing face | Apply soapy liquid point by point to find the leak | Stop the machine, release the pressure, disconnect the power, then clean the sealing face and retighten or replace the parts |
| Abnormal noise from the pump set on start-up, or a protection operates by mistake | The incoming phase sequence has changed, or the terminals are loose | Check the phase sequence as described in the manual, tighten the terminals, measure the insulation | Stop the machine, disconnect the power, correct the wiring and test the operation of the protection |
| The alarm comes and goes, the level reading drifts | The probe was knocked out of position during the move | Compare the level at the sight glass with the displayed value | Recalibrate the infrared level and foam detection |
| The alarm gives a light but no sound | The buzzer wiring came loose during dismantling | Trigger the alarm condition by hand and listen for the sound | Reconnect the wiring and re-test the audible and visual output |
What can be done on the day of the move
- Record the vacuum level, the pressure and the running current from before the move as the reference for afterwards. Without a reference there is nothing to judge normal against.
- Take photographs of the pipe routing and the terminals before dismantling, and check the assembly against the photographs afterwards.
- Mark every new interface, so that these positions are checked first the next time a leak check is done.
- Do not run continuously at full load on the day of the move; run a period at no load and a period at half load first.
- Keep the relocation and the emergency repair in separate time slots, so that a fault that has just occurred does not leave no reference condition to compare against.
The order after a relocation is: re-measure the reference values, then check the new interfaces, and do the interlock test last. Reversing that order is what makes one interface problem look like a failure of the whole machine.