Hi Misuk--

I haven't played on DeltaV yet, but sometimes we've had issues with the 
amplifier housing leaking on our Delta's.  We have the option of turning 
it to "fore-vac" or off when it causes problems on "high-vac".

Also, double check the air pressure on you're pnuematics.  If it's low, 
the valves may start to open on your dual inlet.

good luck...

take care

gerry

Misuk Yun wrote:
> Thanks for your advice on rotary pump and IRMS leak.
>
> The ballast valve was off. I used the exactly same pump oil. I thought about
> the possible false vacuum reading by Penning gauge. But, the false reading
> is not related to the air leak - significant amount of vapour from the
> rotary pump exhaust - in IRMS (the needle valve closed).
>
> Greg, the turbo vent line is okay. I have checked all the O-rings of every
> connections of pumping route. Now, I checked the inside of penning gauge -
> any crack on O-ring. It seemed okay.
>
> I am still struggling to find where to look at. Any suggestion or advice?
>
> Thank you.
>
> Misuk
>
>
>
> -----------------------
> Misuk Yun (M.Sc.)
> Geochemistry Lab Manager
> Department of Geological Sciences
> University of Manitoba
> 125 Dysart Rd. (Wallace Building)
> Winnipeg, Manitoba R3T 2N2
> Canada
> Phone: 1-204-474-8870
> Fax: 1-204-474-7623
> E-mail: [log in to unmask]
>
> -----Original Message-----
> From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf
> Of greg michalski
> Sent: June-19-09 12:47 PM
> To: [log in to unmask]
> Subject: Re: [ISOGEOCHEM] rotary pump and air leak
>
> Make sure your powering on the rotary from the front panel and not 
> bypassing through an external plug.  The panel pump switch must be on 
> to close the turbo vent line...
>
>   At 11:54 AM 6/19/2009, you wrote:
>   
>> Hi, All
>>
>> Right before I was ready to run samples yesterday, the IRMS (Delta V Plus)
>> stopped. I checked the rotary pump - significant decrease of oil level and
>> very hot.
>>
>> First, we thought the pump is dead. But it was not. It seems that the
>> thermal break of rotary pump kicked in because it was too hot.
>>
>> After we stated the pump again, there was lots of vapour coming out of the
>> rotary pump exhaust line. The vacuum reading was not right, either (8E-11
>> mbar). I checked if the rotary pump itself has the air leak, and turned out
>> that the pump is okay.
>>
>> This tells that there is an air leak somewhere in IRMS. I checked the IRMS
>> venting control box and the tip of venting line. They were okay.
>>
>> Is there anyone who has similar experience or has any suggestion?
>>
>> Thank you.
>>
>> Misuk
>>
>> -----------------------
>> Misuk Yun (M.Sc.)
>> Geochemistry Lab Manager
>> Department of Geological Sciences
>> University of Manitoba
>> 125 Dysart Rd. (Wallace Building)
>> Winnipeg, Manitoba R3T 2N2
>> Canada
>> Phone: 1-204-474-8870
>> Fax: 1-204-474-7623
>> E-mail: [log in to unmask]
>>     
>
> Greg Michalski, Assistant Professor
> http://www.purdue.edu/eas/michalski/
> Department of Earth and Atmospheric Sciences
> Purdue University
> 550 Stadium Mall Dr.
> Lafayette IN.47907
>
>