# The Naked Scientists Forum

### Author Topic: vacuum measurements  (Read 2997 times)

#### havril

• First timers
• Posts: 2
##### vacuum measurements
« on: 29/03/2004 14:40:02 »
Somebody told me that the vacuum inside a certain container was 0.5 mbars. I did not have the opportunity to ask him to expand on how the mbar scale works. So I wonder if someone out there can help?

TIA
Harvey

#### roberth

• Sr. Member
• Posts: 246
##### Re: vacuum measurements
« Reply #1 on: 29/03/2004 23:59:11 »
I'm guessing that a mbar is a millibar or one thousandth of a bar. A bar is the atmospheric pressure at sea level and is equal to about 14 psi. When you see a weather map showing isobars (or areas of similar air pressure), the one's below 1000 represent low pressure areas and the ones above 1000 are high pressure areas. These measurements are in millibars.

#### qpan

• Sr. Member
• Posts: 260
##### Re: vacuum measurements
« Reply #2 on: 30/03/2004 11:29:53 »
The metric conversion is 1 bar = 10^5 Pa (Pascals = N/(m^2)), so one millibar = 10^2 Pa.

"I have great faith in fools; self-confidence my friends call it."
-Edgar Allan Poe

#### gsmollin

• Hero Member
• Posts: 749
##### Re: vacuum measurements
« Reply #3 on: 30/03/2004 12:06:08 »
I'm going on memory here, so don't pillory me if I'm wrong... The definition of a bar = 1 million dynes / square centimeter. It converts to about 14.5 psi.

#### The Naked Scientists Forum

##### Re: vacuum measurements
« Reply #3 on: 30/03/2004 12:06:08 »