You unscrew the nut on the black pieces and slide it off to open the ballast.
4 Likes
@IsolationChamberLab
Itâs not dumb at all. I had to ask the same and then took off the entire thing by mistake. The black thing is the ballast, itâs permanently on in that position. The top part is removed to turn it off. Top screw is what you untighten, then the top piece comes off like a plug. Donât take the entire thing off because the electricity will still be connected and that causes it to be hot, real hot. So just use the screw on top to disconnect and youâll be fine. Thank @vacuumdynamics for this info.
So revise what killa said and just take off the plug part.
6 Likes
This is even better cause i know one that melted the black thing while it was off. Thanks for clearing that up for me @Renchi
3 Likes
You are most welcome. I did the the same thing first, cause thatâs what looks like the easiest. But when I went to put it back on is when I felt how hot it was.
1 Like
This is the reason we remove the solenoid on these 2021I pumps when we refurbish them and install the standard manual gas ballast. We have many customers that love these pumps and I would be careful running Kerosene through these pumps too much as we have seen it make the vanes swell.
4 Likes
Google the model number and find a manualâŚany instructions provided on the forum will not meet the same level of detail that the instruction manual will, imho
3 Likes
Respectfully, I agree that the manual is great, but the two methods described here are nowhere to be found in the manual. I have successfully got 2 separate pumps to pull 1 micron whereas the professional tech working on multiple of these only got the pump to pull 2.4 micron. So imho this forum and itâs members have a wealth of info thatâs not covered in said manuals.
5 Likes
Same. I have the manual and while it discusses the automatic gas ballast found on these pumps. No where does it mention how to open it manually.
Iâm glad @Renchi had a better solution.
3 Likes
@Renchi I appreciate the input of the community, if thatâs what you truly believe based on experience then Iâd say both of our opinions hold validityâŚso let me re-specify:
This site has more intricate and detailed information of application of instructions, the manual has time-tested and approved methods for servicing the pumpâmanufacturers will often let out limited information so they can maintain the business of maintenance.
I misspoke, but I believe non-approved practices, like running kerosene, are not necessarily best practices. As someone mentioned, lines swellâthis means certain practices endorsed on the forum donât take into account the materials of construction of these pumps.
Iâd suggest buying a rebuild kit and finding someone who can rebuild. Perhaps the real problem is that we arenât correctly maintaining pumps.
0.02$
8 Likes
The Pfeiffer / Adixen 2021i pump is a solid extraction pump that delivers good vacuum and will rebuild many times over if oil is changed often and not neglected too much. Other less expensive pumps have their place but will likely not rebuild well or at all.
We have rebuilt hundreds of these and can answer most of your questions. We charge about $650-$700 to refurbish them to factory standards
1 Like
I fully understand what you are saying, but Iâve found that other industries doubtlessly do not keep as good care of their pumps as our industry has started to do. Both my pumps came from laboratory settings, outside our industry, and it was clear that they had neglected changing pump oil enough for them to keep pulling ultimate vac. And the safety of using kerosene has been discussed in both threads and private convos, which is why Iâve recommended the use of flushing fluid (recommended by @Soxhlet) over kerosene as it is meant to be used in the same way and is how I got my second pump to pull ultimate vac. So even though we have recommended the use of kerosene weâve tried making users aware to use it sparingly. I thought I was going to have to do a rebuild on the first pump, cause it was really dirty after using the flushing fluid, but then I read about the kerosene flush I had forgotten here and then just did two and continued with the flushing fluid and ballast to pull 1 micron.
But I agree, the manual should definitely be perused before using anything really. So Iâm not disagreeing, just stating that both have their merits. For example I found out about the etho flush here and then got it confirmed by speaking to Welch directly.
3 Likes
Ok you guys have me alittle confused about when to keep the pump âblanked off,â during startup and cleaning.
Please let me know if I have this right. Te manual says to run the pump for one hour, with the intake closed âblanked offâ, and the gas ballast open, prior to use.
- To clean, I should also run with koresene or flushing fluid. Should this be performed with the intake to the pump closed (âblanked offâ) or open?
- Before using the pump, I should run it for one hour with intake closed. Is this every time I use it or only after cleaning? After the hour do I open it to the system I am vacuuming with a valve without pump shut down?
- It was said to damage the pump to rapidly allow air to enter while operating. Does this mean I need a valve between the pump and SPD in order to prevent oil backflow from the pump because I cannot quickly bring it to pressure with atmosphere?
1 Like
I agree that the kerosene trick should be used with consideration of the pump materials, and construction. This trick came from an old hvac tech who was in his 80âs, pump construction has since changed in that time.Flushing oil ,frequent oil changes, proper traps, and gas ballasting are certainly key to a pumps longevity.If you have an older vacuum pump that can withstand using a solvent to clean kerosene is a good choice because it mixes with the pumps oil, youâd never want to use anything like etoh⌠and yes I have seen that lol⌠talk about a pump full of salad dressing 
.
but to recap, @Renchi and @TheGratefulPhil you are both correct.
6 Likes
the purpose of running a blanked off pump is to get it hot before use to reject volitiles, hot pumps are a good thing!
When you perform flushing on your pump start with a hot pump, best is after use. Drain the old oil and refill with flushing oil, run the pump balnked off with the flushing oil for an hour or so, then drain and refill with vacuum pump oil.
to perform a solvent cleaning drain your pumps oil while hot, fill with 50%-50% kerosene and pump oil, blank off pump and run it outside for an hour. Drain the solvent mix and flush your pump with fresh oil. Refill the pump with oil and run again with the gas ballast open and intake blanked off for an hour. Repeat this step several times to rinse out and volatilize any remaining solvent. If your pump is not performing better you probably still have some kerosene somewhere in there. Always consider the pump materials and construction before using a solvent in this manner.
4 Likes
Gas ballast all the way! My latest pump pulled 0.4 micron now. Woooohooooo.
4 Likes
I tried to follow the service manual you posted, the diagrams are awful and donât help much! I couldnât get it all the way apart with those directions. After I cleaned best I could, put it together again, I thought it looked like there should be a gasket on the sight glass in addition to the O ring. Couldnât pull lower than 90micron.
So this manual has waaay better diagrams, but it is not the exact pump folks on this forum have been buying, there are some extra gaskets (like 4A⌠the sight glass has a gasket in addition to the O ring). But this is a very helpful diagram fror me anyway:
3 Likes
Exploded views are good for visualizing the assembly of the components, glad you got it sorted.
2 Likes
The sight glass is plastic on the Alcatel 2021and will require a glass replacement if your flushing with kerosene. Thatâs what Iâve been told anyway. I dont use kerosene though for cleaning.
5 Likes
That type of cleaning isnât suitable for certain models, it all depends on what your pump is made from.When in doubt use flushing oil to wash it out!
3 Likes
I think thereâs a glass sight glass upgrade kit for the 2021i canât remember the company.thatsl sells it though