Weller VP800/801 desoldering station, how many filters are needed?

[AndersJ]

The station has filter cans on the input, on the front panel,
and on the exhaust, on the rear.

The cans have plenty of space for many filters,
and the cap has a spring that implies that a handful of filters could/should be used.

Q1: Is one filter enough, and if so, why is the spring there?
Q2: Or, are many filters needed, stacked one after another?
Q3: Does anyone have a operators and/or service manual?

Grateful for all comments
Anders J

[SeanB]

One filter on the case itself, and in the actual solder station 2 filters stacked. The reason for 2 is that when the first is dirty the one behind will be only mildly contaminated, so you discard the innermost unit and put the slightly used on in the firing line, and put a new one behind it to keep the suction lines and pump clean. Maximises filter life, as they cam be quite expensive. To improve life of the filter in the suction head get a plain stainless steel pot scourer ( check with a magnet it is not steel, and immerse a sample in some slightly salt water for a day to see it does not rust. Beware of plated plastic scourers though, they melt) and cut a small plug out of it to fit ahead of the filter, to catch the molten solder. Small plug, and you can easily toss it along with the solder when it clogs up, saving the filter.