Donaldson 1C485523 Mechanical Float Condensate Drain, KA1/2, DF 0035 to DF 0750

This is the drain that lives in the bottom of a Donaldson ultrafilter housing and quietly decides whether the filter above it is doing any good. When the float sticks or the seat wears, the sump fills, the element sits in standing condensate, and the clean dry air you paid for arrives wet. Donaldson part number 1C485523, the KA1/2 mechanical float drain, fits the DF 0035 through DF 0750 filter housings.

Specifications

• Donaldson part number: 1C485523
• Type: mechanical float-operated condensate drain
• Model designation: KA1/2
• Fits: Donaldson and ultrafilter DF 0035 through DF 0750 filter housings
• Supplied with: O-ring

Mechanical float, and why that matters here

A float drain needs no power and no timer. It opens when there is liquid to discharge and closes when there is not, which means it never vents live air the way a mis-set timer drain does. The trade is that it is a mechanical device sitting in whatever the compressor sends downstream, so oil, scale and pipe debris will eventually foul the seat. That is a maintenance item, not a design flaw, and it is why this part exists as a stocked spare rather than a warranty claim.

Replacing it

Depressurize the housing. All of it, not just the line upstream, because the sump holds pressure after the system is isolated and a drain body under 100 PSI comes out hard. Fit the supplied O-ring dry or lightly lubricated with compressor oil, never with petroleum grease, and do not overtighten the brass body into the aluminum bowl. If the old drain came out full of black sludge, the problem is upstream and the new drain will be back on the bench within a year unless the separator and coalescer are dealt with too.