Air Breather for housing vent. 1

[virata]

Hi guys,

I would like to know what is the significance of having an Air breather for pump (OH1) bearing housing vent? The means of lubrication is flooded. The pump vendor deviates to this requirement.

Appreciate all your input.

Thanks and Regards,
V.

 

[JJPellin]

The need for a breather depends on the style of oiler. If the oiler is a pressure equalized design, no breather is needed. If the oiler is the old-style, non-pressure-equalized type, it may not function correctly if there is no breather. If the bearing housing seals are an air tight design, then the use of a breather can change the function of the oiler. We use pressure equalized oilers, vapor-tight housing seals and no breather.

Johnny Pellin

 

[virata]

I have asked the vendor whether this is pressure equalized design but he states that "a 1-inch bulls eye is provided on the frame to enable monitoring of actual oil level of level in the frame". Also, he adds that constant level bottle oiler not specified on the datasheets. I didn't undertand if this is a "no" to my questions.

Is this "constant level bottle oiler" needed for an equalized oiler design?

Regards,
V

 

[JJPellin]

If there is no constant level oiler installed, it is not necessary to have a breather vent. The need for the breather vent would be to provide equal pressure in the housing if there was a non-equalized oiler installed. With no oiler, there is no need for a breather.

Johnny Pellin

 

[GPRnD]

I'll disagree with the statement that the type or presence of oiler determines the need for a breather.

Regardless of whether an oiler is fitted , the housing will "breath" as it heats up and cools down from start/stop operations. This breathing can pull in dust and moisture depending on where the pump is situated. Typically this will take the path of least resistance which is via the lip seal or labyrinth seal where the shaft exits the housing

There are 4 schools of thought about how to handle this.

1st school is that it doesn't matter much and I'll replace the bearings at every outage to compensate for the introduction of dust/moisture
2nd school is that I'll fit a breather to be the path of least resistance and filter out dust. In some cases people will fit combined breather/driers to handle moisture and dust.
3rd school is to hermetically seal the housing with mag based face seals (aka isomag or equivalent) and an expansion chamber to prevent over pressure.
4th school is the Heinz Bloch view that oil bath is evil and everything should be oil mist

YMMV