The dimensions of the ZYD-100 are 1200×1400×1800 mm and the weight of the machine is approx. 720 kg, which is the net weight of the machine alone. With the base, the guardrails, the accessories supplied with the machine and the transport packaging added, the handling unit is noticeably heavier than the figure on the nameplate, so the lifting plan on site has to be written around the total weight of the handling unit and not around 720 kg. If this one point is got wrong, the problem is built in from the first lift, and at a site where the machine is shipped complete and not dismantled the packaging frame and the base in particular have to be counted into the total weight.
Transport securing: first prevent sliding, then prevent tipping
The most common problem during crated transport is not external impact but the relative movement of the components inside the machine. If the heavy parts such as the tank, the heating tube assembly, the pump set and the motor are not secured separately, the continuous vibration in transit makes them shift slightly and repeatedly inside the crate, the loads on the welds and the clamps become uneven, and by the time the crate is opened on site the oil leaks and the loosened parts are usually exactly at those places. More attention is needed for the parts that are mounted in mid-air, such as the pipework, the pressure gauges and the vacuum gauges: they swing by much greater amounts under vibration than the parts welded to the base, and most of the leakage at the joints starts there.
Protection against tipping has to be considered separately. The upper part of the machine carries the tank and the heating parts, so the centre of gravity is relatively high, and if there is lateral acceleration on a ramp or at a sharp turn the risk of tipping is much higher than on a straight run. The isolating supports built into the packaging, the chocks fitted at the bottom and the choice of the transport route are all there to hold that risk down. If the machine shows clear signs of having been tilted when it arrives at the plant, photographs should be taken as evidence before the crate is opened.
Lifting points and the loads they carry
The lifting points marked on the frame have to be used for the lift. Grabbing the pipework, the pressure gauges, the heating tube assembly or the tank may look convenient, but in reality it subjects those parts to loads far beyond the design, and when the slings are unevenly loaded the machine twists slightly in the air and passes the torque into the frame at the moment it touches down, just after the frame has been levelled. The form of the lifting gear has to match the lifting points; a wire rope slung directly onto an angle-steel lifting point can easily slip off at the moment of the lift, so the connection has to be checked as self-locking before the lift begins.
In the lifting procedure, the trial lift cannot be skipped. For the trial lift, raise the machine slightly clear of the ground and check that it is balanced, that the load really falls on the marked lifting points and that the direction of the tilt is not abnormal; only continue to raise it once this has been confirmed. Continuing to lift with the machine out of square becomes harder to correct the higher it goes, and it has to be corrected a second time when it lands. Finding and correcting a problem during the trial lift costs far less than dealing with it after the machine is on its foundation.
Once in position: the level and the order of the pipework connections
The first thing after the machine is in position is to re-check the level. Settlement and tilt can occur during transport and lifting, and an out-of-level tank is reflected directly in the temperature distribution across the heating section: on the low side the heating tubes reach temperature first, while on the high side the set value is not reached for a long time. The settlement of the foundation is often not complete in one go, so arranging the re-check before the pipework is connected and before the oil is circulated means that any problem found is corrected on a foundation that is far easier to adjust than later on.
- Secure the external pipework first and connect the electrical side afterwards, so that the force in the pipework does not pull the machine out of position.
- Check that the oil inlet side and the purification side correspond; a reversed pipework is only revealed after the power is switched on.
- Do not energise the machine until the pipework connections are complete, so that an electrical operation cannot start the pump set while the circuit is not yet closed.
- Leave the maintenance space clear once the machine is in position, so that the cabinet doors open fully and the filter elements can be withdrawn.
The checks before the first energisation
The first thing after the machine is in position is to re-check the level. Settlement and tilt can occur during transport and lifting, and an out-of-level tank is reflected directly in the temperature distribution across the heating section: on the low side the heating tubes reach temperature first, while on the high side the set value is not reached for a long time. The settlement of the foundation is often not complete in one go, so arranging the re-check before the pipework is connected and before the oil is circulated means that any problem found is corrected on a foundation that is far easier to adjust than later on. If the deviation is too large, check the foundation first and the machine second.
Then check the protective functions. The phase loss and phase sequence protections have to be simulated once on site to confirm that the machine refuses to start when the phase sequence is connected wrongly and that the alarm gives a signal; this step is often skipped during installation, and the problem is only found when the machine is put into service for the first time, at a troubleshooting cost far higher than checking it on the spot. Next comes a no-load jog to confirm the direction of rotation of the pump, then a check that the heating and the temperature control are in their normal positions with the power off, and finally a check that no tools have been left in the tank and that all the accessories supplied with the machine are fitted.
Taken together, the logic behind these steps is consistent: every step has a corresponding failure consequence, and the consequence usually only becomes apparent after the power is switched on, at which point the investigation has become expensive. Keeping the sequence in front of the work is the most direct way of reducing the cost of this kind of rework. If a step has been skipped on site because the schedule is tight, record it; when a problem has to be investigated later, the scope can then be narrowed from the whole machine to that one step.
Accidents on site rarely happen at the moment of lifting; they happen in the checks that were skipped to save time. Every skipped step is paid back twofold once the power is switched on.