We received a brand new Duo 3M as a replacement for our Duo 2.5. When I plugged it into our Delta V advantage IRMS, the pumped gurgled initially, but continued to gurgle audibly. The Duo 2.5 typically stopped gurgling after a few mins. If I put my hand over the exhaust hose (just a 3ft peice of tubing attached to the exhaust port) outlet the sound goes away. I pulled the pump out to isolate the problem and closed off the inlet. The sound was still present so I know its coming from the pump. The Duo 3M works and gets to vacuum but the noise it a bit irritating. I spoke to a representative who told me the sound was normal and to get a silencer ( exhaust filter silencer).
Does anyone have any input or information?