Tips on Roughing Pressure

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
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Jeremy Adams
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Joined: Tue Aug 19, 2014 1:08 am
Real name: Jeremy Adams
Location: Chicago Ill

Tips on Roughing Pressure

Post by Jeremy Adams » Wed Jul 11, 2018 6:25 pm

It turns out my dual stage 12 CFM roughing pump is only reaching 40 microns at its lowest. I would prefer it to reach at least 15 microns for roughing my diffusion pump. It is only about one year old and doesn't have much wear so it should be capable of achieving close to its rated ultimate pressure of 2 microns. The connection to the pressure gauge when it reached 40 microns was KF sealed and seemed leak proof but I can double check this. I also replaced the oil and cleaned out old dirty oil in the box holding the motor.

Is the oil I'm using good enough for the roughing pump? It is Mobil 1 vacuum oil, picture attached below. What else can I do to get lower roughing pressure?
Attachments
Roughing Oil 1.jpg
Roughing Oil.jpg
Oil used for pump
Clean.jpg
Inside of motor container cleaned

John Futter
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Re: Tips on Roughing Pressure

Post by John Futter » Wed Jul 11, 2018 7:05 pm

What does the manual for your pug say as to the reccommended oil?
Is this a direct drive or pulley driven pump? A pic of pump would be nice
Have you rung Mobil's tech department to check whether the mobil oil is actually a replacement for the reccommended oil?
Have you run the pump with gas ballast open for a couple of hours to rid the oil of volitles?

Jeremy Adams
Posts: 27
Joined: Tue Aug 19, 2014 1:08 am
Real name: Jeremy Adams
Location: Chicago Ill

Re: Tips on Roughing Pressure

Post by Jeremy Adams » Wed Jul 11, 2018 9:51 pm

The manual is vague and says that a 'High Vacuum Pump Oil' is required but does not specify a brand or type. I can try to get in contact with someone who knows about this oil but it's unlikely they will confirm it works for my pump specifically (which is why I posted here to see if you guys know more about roughing pump oil). Attached is a picture of the type of roughing pump I'm using. Pretty sure it is a direct drive pump.
Attachments
mf-lD-ghKLI5-bqV5tmkNlA.jpg
Type of roughing pump I'm using
mf-lD-ghKLI5-bqV5tmkNlA.jpg (16.95 KiB) Viewed 590 times

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