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Re: Spark Gap(rule of thumb)
Subject: Re: Spark Gap(rule of thumb)
Date: Mon, 2 Jun 1997 17:48:57 +0500
From: "Alfred A. Skrocki" <alfred.skrocki-at-cybernetworking-dot-com>
To: Tesla List <tesla-at-pupman-dot-com>
On Fri, 30 May 1997 16:34:18 GMT Robert Michaels
<robert.michaels-at-online.sme-dot-org> wrote;
> The "Handbook of Chemistry & Physics" (Chemical Publishing Co.)
> has a table of spark-gap distances in air at STP for needle
> point gaps, and gaps using spherical electrodes of various
> diameters. At least the older editions do -- not sure about
> the more recent ones.
Robert, I am sorry to report that the 77th edition (1996-1997)of the
CRC "Handbook of Chemistry & Physics" does NOT contain the table of
spark-gap distances, it also no longer carries information on the
dialectric strength or power factor of dialectrics. All the formulas
and helpfull lab hints are gone too! By contrast, I also have the
33rd edition (1951-1952) which has tables of "properties of
dialectrics" including; dialectric constant, dialectric strength,
volume resistivity, and power factor! It also contains an entire
chapter devoted to electricity and magnetis including the spark-gap
voltages! If you have any of the older editions HANG ON TO THEM! The
new ones are worthless, except for chemistry! BTW for the benefit of
those who may not be able to find an old copy, here is the spark-gap
table;
SPARK-GAP VOLTAGES
Based on results of the American Institute of Electrical Engineers
Air at 760 mm, 25 C.
-------------------------------------------------------------------
Peak | Diameter of spherical electrodes, cm |
Voltage, |---------------------------------------| Needle
Killovolts| 2.5 | 5 | 10 | 25 | Points
----------|---------|---------|---------|---------|----------------
5 | 0.13 | 0.15 | 0.15 | 0.16 | 0.42
10 | 0.27 | 0.29 | 0.30 | 0.32 | 0.85
15 | 0.42 | 0.44 | 0.46 | 0.48 | 1.30
20 | 0.58 | 0.60 | 0.62 | 0.64 | 1.75
25 | 0.76 | 0.77 | 0.78 | 0.81 | 2.20
30 | 0.95 | 0.94 | 0.95 | 0.98 | 2.69
35 | 1.17 | 1.12 | 1.12 | 1.15 | 3.20
40 | 1.41 | 1.30 | 1.29 | 1.32 | 3.81
45 | 1.68 | 1.50 | 1.47 | 1.49 | 4.49
50 | 2.00 | 1.71 | 1.65 | 1.66 | 5.20
60 | 2.82 | 2.17 | 2.02 | 2.01 | 6.81
70 | 4.05 | 2.68 | 2.42 | 2.37 | 8.81
80 | ..... | 3.26 | 2.84 | 2.74 | 11.10
90 | ..... | 3.94 | 3.28 | 3.11 | 13.30
100 | ..... | 4.77 | 3.75 | 3.49 | 15.50
110 | ..... | 5.79 | 4.25 | 3.88 | 17.70
120 | ..... | 7.07 | 4.78 | 4.28 | 19.80
130 | ..... | ..... | 5.35 | 4.69 | 22.00
140 | ..... | ..... | 5.97 | 5.10 | 24.10
150 | ..... | ..... | 6.64 | 5.52 | 26.10
160 | ..... | ..... | 7.37 | 5.95 | 28.10
170 | ..... | ..... | 8.16 | 6.39 | 30.10
180 | ..... | ..... | 9.03 | 6.84 | 32.00
190 | ..... | ..... | 10.00 | 7.30 | 33.90
200 | ..... | ..... | 11.10 | 7.76 | 35.70
210 | ..... | ..... | 12.30 | 8.24 | 37.60
220 | ..... | ..... | 13.70 | 8.73 | 39.50
230 | ..... | ..... | 15.30 | 9.24 | 41.40
240 | ..... | ..... | ..... | 9.76 | 43.30
250 | ..... | ..... | ..... | 10.30 | 45.20
300 | ..... | ..... | ..... | 13.30 | 54.70
-------------------------------------------------------------------
Sincerely
\\\|///
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( -at- -at- )
-----o00o-(_)-o00o-----
Alfred A. Skrocki
alfred.skrocki-at-cybernetworking-dot-com
.ooo0 0ooo.
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