Once a machine has arrived on site, the question of whether the settings should be changed and how is one of the most common questions of the commissioning stage. Changing too little leaves the oil condition unmatched, changing too much can push the machine beyond what it can do. The point of a commissioning parameter sheet is to separate these items: what can be changed, how far it can be changed and what the decision is based on, so that the site chooses from conditions rather than from impressions.
The temperature setting: adjustable, but set by the oil and the water content
The temperature control range of the TYA series is 45~80 °C. This is the range the machine can hold, not a free choice of any number inside it. The lower end corresponds to the temperature the heating capacity just maintains, and the upper end has to keep a margin to the flash point, because the closer the oil temperature gets to the flash point the more oil vapour flashes off and the load on the condensation section and the vacuum pump grows.
When the water content is high, the upper end of the temperature is pressed down to 70 °C. This is not making the result worse, it is a different balance: when there is a lot of water, buying degassing speed by raising the temperature is not a good trade, because a large volume of flashed oil vapour means more oil vapour entering the vacuum system and more chance of contaminating the condensation section and the pump oil.
As far as heating is concerned, the ZYD-100 uses far infrared carbon fibre heating. Far infrared heating brings the surface up quickly and warms the tank more evenly, which helps with temperature uniformity, but the setting still has to follow the type of oil and the quantity in the tank.
The vacuum setting: the range is given and should not be changed at will
The working vacuum of -0.08 ~ -0.0999 MPa is the rated range of the ZYD-100, and the limit vacuum of ≤5 Pa describes what the system can reach when it is drawn down properly. Both numbers describe what the vacuum system can actually do, and they are not things a setting can decide. If the vacuum setting is raised on site to shorten the processing time, the target is simply not reached and the machine only ends up running in the lower vacuum range again and again.
The three kinds of item on a parameter sheet
| Parameter | As delivered | Range on site | Basis for the change |
|---|---|---|---|
| Heating temperature setting | A setting inside the 45~80 °C range of the TYA series | Adjustable inside the range, upper end 70 °C when the water content is high | Type of oil, water content, flash point |
| Vacuum system setting | Working vacuum -0.08 ~ -0.0999 MPa | Not recommended for adjustment on site | Bound by what the vacuum pump and the Roots blower can actually reach |
| Overpressure alarm and shutdown | Overpressure alarm with sound and light warning and shutdown | Checked against the pipework on site and confirmed | Pressure rating of the pipework and the pressure drop of the filtration section |
The three mistakes that are easily made while adjusting
- Changing several settings at once, so that afterwards it is impossible to tell which one produced the change. The right way is to change one item, observe one round, and only then move on.
- Copying somebody else's setting. The setting has to follow the oil, the water content and the pipework of this machine, and a copied value is only a reference.
- Changing without recording. If the new setting and the reason for it are not written down, nobody can tell what the basis was the next time the oil type changes or the job is handed to another person.
Write down what was changed
Once a setting has been changed, a record has to be kept: when it was changed, the values before and after, and the reason. That record serves two purposes. It allows a fault to be traced back to the state the machine was running in, and it allows the next change of oil type to be compared with the previous setting, so that it can be judged whether that setting still fits.
One more point is easily overlooked: the settings on the commissioning sheet have to be read together with the working pressure and the filtration accuracy. Cleaning and element replacement become necessary once the pressure passes 0.3 MPa, and the filtration accuracy of ≤1 μm and the cleanliness of NAS 1638 class 5 describe the capability of the whole machine. Together these figures decide what quality of oil the machine can deliver steadily at the settings in use.
A setting can be adjusted, but every one of them should have a written reason behind it.
