organicchemist25 - 11-3-2015 at 20:36
I had a cheap vacuum gauge that quit working (internal parts must be seizing up) and I did buy a digital (used) manometer. I am not sure if it is
correct or calibrated correctly, or even how to for that matter.
So, I am looking to get another one. Anyone have some recommendations?
I have been searching for McLeod and other various manometers. Im not real pressed for cost, but 200-300 is max I would like to spend.
I want a nice one (of any highly recommended one) that will last and be easy to calibrate if needed.
Thanks
Bert - 11-3-2015 at 20:59
Got some mercury and a glass tube?
http://www.mrbigler.com/moodle/mod/lesson/view.php?id=1942
[Edited on 12-3-2015 by Bert]
organicchemist25 - 11-3-2015 at 21:05
I have a little bit. I'd say approximately 2-3 ml. I could probably get some more. How much are you thinking I would need?
Bert - 11-3-2015 at 23:17
Total volume depends on tube Dia., but enough to fill about 100 cm of vertical tube. Look at the link or google "mercury manometer" for diagrams-
Or if you've got lots of space, water works. You will need about 10 meters of height with a water filled tube, though. Mercury density allows for a
bench top tool.
Sulaiman - 12-3-2015 at 10:32
What vacuum range do you want to measure?
Magpie - 12-3-2015 at 12:55
I use (and like) a Bennert manometer. It uses mercury.
organicchemist25 - 12-3-2015 at 19:48
I really do not see myself going below 0 mmHg/torr
Then again, I have not came across a need yet to go into the negative range...but when I do, Ill upgrade the equipment. I have a pump capable of
approximately getting down to 20-30 torr. I have a Dewar cold trap setup for the vacuum.
organicchemist25 - 12-3-2015 at 19:50
Does the mercury come with it? or would I need to get some Hg and fill it myself?
Any calibrating required, Magpie?
organicchemist25 - 12-3-2015 at 19:52
I appreciate everyone's responses 
Magpie - 12-3-2015 at 21:00
They are usually sold without mercury. I bought mine used off eBay. I filled it with mercury myself. It's a little tricky as the tube must be fully
evacuated before pouring in the mercury.
As for calibration it really shouldn't need it if you've fully evacuated the tube to P=0 mmHg before filling. I did check mine against an Inficon
Pilot Plus vacuum gauge.
[Edited on 13-3-2015 by Magpie]