The Big Idea
The Press shows an alarm for Main Filter Dirty which indicates that the recirc oil filter is causing high pressure in the recirc loop. The filter cartridge will bypass if dirty which potentially leaves the tank highly contaminated. Change the filter if the alarm is on. Also have filters in stock and make a practice of regular filter replacement before the alarm sounds. A pressure gauge is on the system for monitoring the condition of the filter. New filters run as low as 5 psi.
If a filter is neglected, the oil gets dirty. The replacement filter will quickly load and require replacement. Multiple filters may be required to "clean up" a neglected tank.
Which Filter do I have?
The best way to tell if you have a Stauff or Donaldson filter is by the cap. If the car is blue, you have a Donaldson filter. If the cap is not blue, you have a Stauff filter.
Stauff Filter (No Blue Cap)
Donaldson Filter (Blue Cap)
Donaldson Filters
There are two types of Donaldson filters for Milnor presses.
27E120
In January of 2021, Milnor presses use a 5 micron, open body filter, part number 27E7120. The filter in this unit is 27E7112E. This unit is about 19" long and requires a little bit of head room to change the filter. This filter has a 50 PSI bypass capability and a 44 PSI pressure indicator switch. If you have cold morning startup issue, consider changing your filter to this one. Wiring for the pressure indicator switch is as follows: Red - N/O, Black - COM, Green - N/C.
27E7112
Before January 2021. This filter has an internal tank canister body and is about 8.25 inches long.
This unit can be replaced with the 27E7120 if you want larger a large filter. They upper head unit also looks the same from the top. So, be sure you are picking the right filter cartridge for replacements.
Replacement filter cartridge is :
27E7112B for 10 micron - Donaldson 171846
A complete canister replacement is pn 27E7112
Stauff Filters
Stauff filter canister shown as item 7.
The replacement filter cartridge is:
27E7106A for 10 micron
27E7106B for 25 micron
A complete canister without filter is 27E7106.
Other helpful information
For any press, the recommended filter is 10 micron or smaller. Filters are rated by a Beta value. A Beta 1000 of 11 microns means that 99.9 percent of the particles over 11 micron are trapped.
There is an alternate of 23 microns. It will trap 50 percent of the particles over 7 micron and 99.9 percent of the particles over 23 micron.
Milnor would prefer fluid that is filtered to 10 micron or smaller. This helps the pump and valve components in the long term. But, for a decade replacement filters were sold at 23 micron (on presses with multi manifolds) with little or no evidence of wear problems.
