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Do you want the higest quality yield from your kiln
- day after day after day..? Proven as the the most accurate method of measuring
heat work, Bullers Rings can help maximise profits. Selected by the world's
leading ceramic producers.
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To develop the optimum properties
of a ceramic product, the control and uniform application of the heat work
is essential. Even the latest kilns, with microprocessor temperature controls,
provide for 'spot' readings only, at fixed points, and cannot monitor the
effects of heat work or kiln loading on the firing process. Variations in
local temperatures within a kiln can exceed 100 degrees, introducing a variable
that is difficult to predict. A number of devices have been developed to
measure heat work in a way that is similar to the ceramic products themselves.
Most of these devices rely on visual deformation - ony Bullers Rings and
Bullers Bars use controlled contraction which can be recorded as a single
number to measure heat work.
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Bullers Rings provide the only accurate
and measurable means of assessing kiln performance. Like the products themselves,
the rings react to the effects of time and temperature, the combined effects
of which produce a shrinkage in the ring. This can be accurately measured
on a simple gauge to determine the heat treatment to which it has been subjected,
and which is shown by single number.
In addition to monitoring kiln performance, Bullers
Rings can be used to map the thermal performance of a kiln by placing them
at various points across the setting. They can also be used to monitor the
progress of a firing by withdrawing rings from the kiln at intervals measuring
the contraction. |
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While the principle for making Bullers Rings was
determined over 80 years ago, they are today made using the latest production
technology.
To ensure consistency accuracy Bullers Rings are manufactured to a precise
materials specification under strict quality controls.
Each batch of sprayed dried materials is pretested to our exacting standards
before being released to manufacture.
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Advance production techniques are audited on
a daily basis to show that the optimum quality is achieved. Bullers Rings
has been adapted as part of a quality control system by major manufacturers
worldwide and are described in the BS1041: 1988 - code for temperature
measurement part 7, temperature/time indicators.
Each batch is fully traceable and coded, together with detailed customer
records a practice which ensures the consistency of future supplies.
Customers are advised to calibrate new batches against existing rings
to guarantee consistency of measurement.
Manufacturing processes are in accordance with BS EN ISO 9002.
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For greater efficiency and minimal checking we can
offer major customers the facility of dedicated batchs, from which they
can draw a known and consistent supply of rings over a given period.
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Bullers Rings are used, in 45 countries worldwide,
by the leading producers of ceramic products including famous names such
as Wedgwood, Noritake, Royal Doulton and Ideal Standard. Applications ranging
from earthenware, bricks and tiles to bone china, refractories and hard
porceline are accommodated by the four grades of ring which enable the temperature
range 960°C (1760°F) - 1420°C(2988°F) to be the monitored.
The use of just a few rings enables craft potters and other users of small
kilns to ensure the same accuracy of kiln environment as enjoyed by major
ceramic producers.
Rings are used in all types of kiln, continuous or intermittent, providing
an indicator of consistency of firing. By locating rings in holders adjacent
to kiln access ports it is also possible to withdraw rings during the firing
process to accurately control the final stages.
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Bullers rings should be placed across a Kiln setting
in such a way as to obtain maximum benefit from their use. They can be placed
flat or vertically by means of a special holder. Taylor Tunnicliff technical
department are pleased to advise customers on the specific placing of rings
to suit their application and kiln.
After firing the extent of the contraction experienced by the ring is measured
by placing the ring on a Bullers Ring gauge. Two types are available; the
simple Vector gauge where a ring is inserted between two converging guide
rails and a reading is taken direct from the engraved scale, or the traditional
Index gauge whether the ring is placed in a holder and the contraction is
measured by means of an extended pointer which reads against a scale. Readings
to the nearest half division should be taken across several diameters and
a mean value obtained.
Gauge readings should not be converted to firing temperatures to describe
firing conditions. The temperatures shown in the table are fore guidance
only as many factors of firing can affect the ring value / temperature relationship.
The Index gauge is designed for long life incorporating tungsten carbide
wear resistant contact pointers and adjustable pointer. Check rings are
available to enable customers to calibrate their gauge. Since differing
kiln conditions, firing rates, etc., can effect ring performance, customers
are advised to calibrate new batches against existing rings under their
own firing conditions.
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Approximate
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Low Temp.
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Standard
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High Temp.
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High temp.
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Approximate
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Temperature
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Ring No.
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Ring No.
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Ring No.
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Ring No.
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Temperature
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° Centigrade
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55
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27
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75
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73
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° Fahrenheit
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960
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3
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0
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0
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1760
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970
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7
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1
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1
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1778
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980
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11
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2.5
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2
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1796
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990
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15
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4
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3
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1814
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1000
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18
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5.5
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4
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1832
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1010
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21
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7
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5
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1850
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1020
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24
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8.5
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6
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1868
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1030
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27
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10
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7
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1886
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1040
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30
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11.5
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8.5
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1904
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1050
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32
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13
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10
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1922
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1060
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34
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14
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11
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1940
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1070
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36
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15.5
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12.5
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1958
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1080
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37
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17
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14
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1976
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1090
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38
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18.5
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15.5
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1994
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1100
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39
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20
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17
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2012
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1110
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21.5
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18.5
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2030
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1120
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23
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20
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2048
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1130
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24.5
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21
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2066
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1140
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26
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22
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2084
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1150
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27
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23
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2102
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1160
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28.5
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24.5
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2120
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1170
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30
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26
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2138
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1180
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31.5
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27
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2156
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1190
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33
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28
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2174
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1200
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34.5
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29
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2192
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1210
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36
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30
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2210
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1220
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37.5
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31
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2228
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1230
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38.5
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32
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2246
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1240
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40
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33
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2264
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1250
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41.5
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34.5
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2282
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1260
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36.5
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2300
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1270
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38.5
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2318
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1280
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40
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29.5
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2336
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1290
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42
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2354
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1300
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44
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31
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2372
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1320
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46
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34
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2408
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1340
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37
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2444
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1360
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40.5
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2480
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1380
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44
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2516
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1400
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48
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2552
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1420
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51
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2588
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NOTE 1
The temperature reputed to be measured by means of Bullers Rings should
be designated by the Gauge number of the ring and not by corresponding
temperatures according to the above table which represent mean values
only. |
NOTE 2
These values should be used with a measure of reserve because they
are dependant on the firing cycle to which the rings are subjected. |
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