Why Choked Filter increases Lube Oil Circuit Pressure? 1

[ahsanb]

Hi Guys, We use Sundyne LMV 331 pumps and we change its lube oil circuit filter after every 6 months. Whenever we need to change the filters the circuit's pressure increases, I need clarity about the following if you guys could help:

Doest this has anything to do where the Pressure Gauge is installed(Upstream or Downstream) of Filter?

High Pressure in circuit means low pressure being delivered in the gearbox?

 

[micalbrch]

As the pressure gauge is the only way you can monitor the pressure its location has of course something to do with the pressure reading. If the circuit pressure increases after exchange of the filter the gauge will be installed behind the filter. If it is installed in front of the filter the pressure will decrease with a new element. Depending upon this you can answer yourself the question about the pressure delivered to the gearbox.

Do you have the Sundyne Instruction & Operational Manual for this pump type? You can download it from the Sundyne website.

 

[ahsanb]

Thank you micalbrch, like I said we change it when we have high pressure reported in P.G.and yes we have high Sundyne O&M Manual for the model but it does not say much about lube oil circuit and ways to troubleshoot problems in it.

Have you ever worked with this model yourself, if so could you please tell me that does your auxiliary lube oil circuit is such that you have to close the external pump to change the filter?

We have been thinking of doing a modification to the circuit so that we can change the filter by doing some isolations but yet keep the circuit and in turn the pump running so that we can avoid operational downtime. Any ideas about that if you have already worked on it?

 

[JJPellin]

This model of Sundyne pump uses an internal, shaft-driven main oil pump in the standard configuration. The external oil pump is typically a pre-lube pump and is not intended to supply full oil flow and pressure for the gearbox. In this arrangement, the external pre-lube pump should not be running when the main pump is running.

The standard configuration for a Sundyne includes a single, screw-on filter. As such, the main pump must be shut down to change the filter. You can install a remote dual filter arrangement with a switching valve. We have this on our large Sundyne compressors. This is the only way I am aware of that would allow you to switch filters on a running unit. You can contact Sundye and they can provide details on this retrofit.

The standard location for a pressure gauge on this pump would be near the top of the gearbox. This would read the pressure in the oil port that feeds the upper bearings. This would be reading pressure downstream of the filters. If you have a pressure gauge installed at a different location, you could be reading pressure upstream of the filter.

I believe we have about 8 pumps of this model. None of them have a dual filter arrangement. All of them are fully spared and we shut down each individual pump in order to change the oil and filter every 6 months.


Johnny Pellin