BAIRD &TATLOCK (LONDON) LTD. 



The amount of heat which can be rejected up the chimney per Ib. of coal by a careless or inefficient stoker is almost 

 Jible, but even the most careful stoking is handicapped if no means are at hand for determining exactly what is happening 

 3 furnace, and this is particularly the case when a change-over takes place from one grade of coal to another having a different 

 >osition. A method of stoking which gives very good results in the one case may be very inefficient in the other, and tho 

 satisfactory method of obtaining a clear conception of what is actually occurring in the furnace, and so remedying any 

 ciency, is to obtain frequent analyses of the flue gases." 



In addition to being a control on the fireman it is a check on the quality of the fuel supplied by the coal factor. There are 

 euower plants In which the saving of fuel directly due to the use of a CO, recorder would not be sufficient to pay for the Instrument 



within six months. 



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4772 

 A portion of an actual record. (Full size.) 



The principle on which ths Bl-Meter C0 a Recorder works. Fig. 4771 illustrates the Bi-Meter CO, Recorder with the doors 

 led. The sample of the products of combustion is drawn from the flue through the recorder by means of a water aspirator. 



gas is first cleaned by being passed through a soot filter, and is then carried through the first of two small meters. It next 

 ses through an absorption chamber filled with lime, in which the CO, is absorbed. The remainder of the gas now passes 

 lugh the second meter, from which it emerges to the atmosphere by way of the water aspirator. 



The two meters are connected by a differential gearing to the mechanism driving the recording pen. 



It will be readily seen that, due to the absorption of the CO,, the volume of the gas passing through the second meter is 

 than that which passes through the first meter, and that the difference in these volumes is equal to the amount of CO, absorbed 

 ii he absorption chamber. 



The differential gearing worked by the meters thus causes the pen to rise at a speed dependent on the proportion of CO, 



a orbed. After a certain definite volume of flue gas has passed through the first meter, the pen is made to drop to its initial 



tion, from which it again starts to record. It is of course necessary that the gas should be at the same temperature when 



ling through the two meters, and to ensure this being the case a temperature equalizer is provided through which the gas 



ics just before entering each meter. The equalizer consists simply of a series of water cooled pipes through which the gas 



p ses in a similar manner to the steam in a feed-water heater. 



As many as 25 analyses per hour may be obtained with the gas tester, but this number can be reduced by controlling the 

 junt of gas passing through the meters. 



A complete record chart is 15 in. long and covers a period of 24 hours. Fig. 4772 reproduces, full size, a portion of an actual 

 >rd obtained with one of our instruments at the Cambridge Electric Supply Co.'s Power Station. 



Advantages of the Bi-Meter C0 2 Recorder. Briefly the advantages of this recorder may be summarized as follows : 



(1) Since the essential part of the recorder consists simply of two ordinary gas-meters, It Is simple, easily understood, and 



runs continuously with scarcely any attention beyond changing the charts and renewing the Ume. 



(2) The Instrument Is enclosed In a metal case and contains no glass parts. It Is as robust as an ordinary gas-meter. 



(3) No Indlarubber tubing is employed, metallic piping being used throughout. It Is therefore especially suitable for use 



In hot positions and In the tropics. 



(4) Since the gas flows uniformly and continuously through the meters, there Is no tendency for any portion of the apparatus 



to stick. 



(5) The absorbent material used Is dry lime. 



(6) The initial cost of the recorder Is low. 



(7) The cost of running is also very low, being approximately as follows : 



(a) About one pennyworth of lime is used monthly. 



(b) About 29 gallons of water per hour operate the instrument. 



(c) The cost of renewals or repairs is practically nil. 



Leaflet dealing with " Instructions for Erecting the Bi-Meter CO, Recorder " describes the details of the instrument more fully. 



shall be pleased to send a copy to those interested. 



A complete outfit consists of the actual recorder with the following accessories : Water tank with ball-cock, soot filter, 

 ake pipe, two tin boxes containing lime, 100 record charts, one water-cock, and one gas-cock with keys, drain pipe funnel, 

 o, for use when first filling the gas-meters : one bent funnel, a length of one foot of rubber tubing, and a tin can containing 

 tres of oil. 



CHEMICAL AND SCIENTIFIC APPARATUS AND PURE CHEMICALS- 



871 



