Sir/Ma'am,
I have a vacuum pump (model. Recently, I have been facing the issue of vacuum pump oil leaking into the vacuum bagging pipe. I am attaching the photos below. Kindly help me understand and solve this issue.

Bhanu

model name is ECVP425

This could happen if you leave the tap on the pump open after you've switched-off the pump, as the vacuum inside the catch pot or vacuum line would draw the oil from the pump. 

it's only likely to be vacuum acting upon the oil so check that the tap is isolating the pump side of things after clamping off your parts

Bingo ^ 

These older style pumps don't have a one-way valve on the inlet, so if you don't shut it off afterwards then you essentially 'infuse' the oil out of the pump.

The new pumps from EC have a one way valve built in so this isn't an issue.

Thank you, Mark and Hanaldo for the advice. It works.