View Full Version : Oil Pump

18-01-2015, 04:20 AM
Hello to everyone,

Sab 202 SF it's oil pump will run continuous or part time?
I am working with sabroe ammonia compressors. I have confusion .

Suction pressure -0.5 Barg


18-01-2015, 05:48 AM
Sab202 from memory needs minimum 6 bar differential between suction & discharge pressure to run without oil pump.
If less than 6 bar oil pump starts.

18-01-2015, 07:56 AM
Hi Shaaf.
As usual Ranger is well informed.
The actual operation of the oil pump is based upon the settings within your Unisab setup!
Meaning as a general rule the pump will start up and once the oil flow switch is satisfied (energised) the comp will start after 10 secs.
Once running if the differential between P1 and P2 drops below 2.5bar the pump runs until the diff is above 4bar.
These pressures are adjustable within the Unisab to suit application's. As directed by Sabroe at commissioning.
They use their own special software to calculate setup based upon the customers requirements.

If the comp is used as a booster then the pump will run all the time.
If you are experiencing a modulating pump look at your operating pressures for what is switching the pump on and off?
Obviously I you have more than 1 comp you could cross reference the settings.
I hope this helps?

Incidentally what are you running to have such a low negative suction pressure?
Is that normal?
If not then that may be the issue?

18-01-2015, 08:39 AM
As usual upside down.

Just to add to Grizzly's post.

Oil pressure after oil filter minus suction pressure is basis for oil trip set point.

Oil pump start at 2.5 bar & stop at 4 bar might be standard setting.


18-01-2015, 10:42 AM
I just checked two compressors r in operation ..parallel.
Oil pump being operated's status
Sp. -0.4 barg
Dp. 2.5 barg
Op. 1.9 barg
Not being operated
Dp. 2.6
Op. 1.9

Compressors are running as booster

18-01-2015, 10:52 AM
Hi Shaff.
You need to talk to Sabroe.
I believe if you are running in Booster mode the Pump should be running all the time.
Which is a selection setting within the Unisab.
Your differential pressures are just on the border line hence the on / off of the pump.

Oil pump start at 2.5 bar & stop at 4 bar might be standard setting.
That is why I was trying not to counter your suggested operating pressures my friend. It is indeed a standard setting.

You now know why the pumps on and off!

It should not be to difficult to sort out!

18-01-2015, 02:48 PM
Thanks both of you my seniors. I got what you suggested. Thanks