When using the regulator for long periods of time, this is perfectly normal.  This is because, in essence, the pump is operating under a load for a prolonged period so you get a very small amount of oil back splatter in the hose.  In normal operation,  the check valve prevents any significant amount of oil flowing up the inlet pipe when the pump is switched off.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

good morning,
I vacuum bagged 5 layers (1.7m x 0.500m) 650 carbon fibre.  I have a DVP EC.4 Compact Composites vacuum pump fitted with a SMC vacuum regulator and vacuum leak flow indicator.  The indicator showed there were no leaks in the bag. The pump ran for 9 hours and the timer shut it down.  When I arrived in the morning and disconnected the pump there was about 1cm of oil in the tubing between the pump and the regulator.  I can replace the tube, but would like to know if this is normal? (as it hasn't happened in the 20+ times I've used the pump previously) or is it indicating a problem? On your website it indicates that oil should not flow back into the tube. Any advice is appreciated.
As always, Thank you