# Thread: A/C Conversion Factor Quiz Question

1. Professional Member
Join Date
Sep 2002
Location
South Dakota
Posts
6,580
Post Likes
The number 25,400 relates to

a. Microns per inch
b. BTU per Ton
c. CFM per Ton
d. CFM per HP
e. Watts per HP

For extra credit, how did they choose the number 25,400?

2. a.
cr=?

3. A. rounding

4. Regular Guest
Join Date
Aug 2004
Posts
138
Post Likes
A. microns per inch
Gee,extra credit?
2.54cm=1 inch,so
25,400micrometers=1 inch

5. Professional Member
Join Date
Sep 2002
Location
South Dakota
Posts
6,580
Post Likes
Originally posted by highlimit
A. microns per inch
Gee,extra credit?
2.54cm=1 inch,so
25,400micrometers=1 inch

Excellent! I grant you a gold star sir!

6. Hey he was looking at my paper!

7. Geez, Norm, you must be psychic. I wish you'd posted that yesterday. I looked all over for that same thing this morning before finding it.

I was trying to figure out why they didn't make direct reading analog pressure type micron gauges. After finding out that there are over 3/4 of a million microns between zero and 30" inches of vacuum, I realized that in order to display the graduations at 1/10" apart, it would take over 1 mile of gauge space to accomodate them. Guess I need a bigger truck!!

Actually most of the digital ones only go from 50-5000, but still.....

8. Professional Member
Join Date
Sep 2002
Location
South Dakota
Posts
6,580
Post Likes
Originally posted by midhvac
Geez, Norm, you must be psychic. I wish you'd posted that yesterday. I looked all over for that same thing this morning before finding it.

I was trying to figure out why they didn't make direct reading analog pressure type micron gauges. After finding out that there are over 3/4 of a million microns between zero and 30" inches of vacuum, I realized that in order to display the graduations at 1/10" apart, it would take over 1 mile of gauge space to accomodate them. Guess I need a bigger truck!!

Actually most of the digital ones only go from 50-5000, but still.....
Zero microns is a perfect vacuum. Since there are 25,400 microns per inch, a micron gauge at atmospheric pressure would read 762,000 microns. So the micron gauges don't start indicating microns until we get down to 5000 microns or so. By limiting the instrument range the accuracy is increased and the cost of the instrument is decreased.

9. Regular Guest
Join Date
Oct 2002
Posts
1,124
Post Likes
a........because of reading high limits answer

10. I had to do this by process of elimination A micron per inch

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•

## Related Forums

The place where Electrical professionals meet.