I don't have any gurgly noise issues with my 3M or 5M pumps, except upon initial pumpdown for about 5-10 seconds. After that, they are quiet. I've interpreted that to indicate that the noise should only happen when evacuating from high pressures. I do recall that some noise is noticeable when the exhaust line was loose, but noise disappears when the exhaust line is tight fitting.

So it seems that just accepting this noise as normal is not right. 


On Tue, Jul 9, 2019 at 10:50 AM Hill, Brett (AAFC/AAC) <[log in to unmask]> wrote:
We purchased a new Delta V advantage that was installed in March.  It came with a Duo 1.6 that is very gurgley (is that a word?).  It hasn't yet given us any problems, and vacuum is good, but it was tough to get used to hearing that noise all the time when normally it is cause for concern.  I mentioned the noise when it was installed and the installer told me the same thing -the sound is normal

-----Original Message-----
From: Stable Isotope Geochemistry <[log in to unmask]> On Behalf Of Peter R
Sent: Tuesday, July 9, 2019 10:46 AM
To: [log in to unmask]
Subject: [ISOGEOCHEM] Duo 3M / Rotary Vane pump Gurgling

Hi all,

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?