FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1921
1921 - 0282.PDF
discovered that acetone has the power of absorbing acetylene up to twenty-five times its own volume for each atmosphere pressure at a temperature of 10 degrees C, so that, for instance, at a pressure of 10 atmospheres, it absorbs two hundred and fifty times its own volume of acetylene. The receptacle in which the gas is stored after it has been Fig. 5. Diagram of the "mixer" of the automatic aerial lighthouse. purified and dried, is generally known as a " gas accumulator," and is similar to the familiar oxygen cylinders. The cylinder is of drawn steel and filled with a porous substance (80 per cent, porosity). This is saturated with acetone before the cylinder is charged with acetylene. Gas •tored in this way is classed by the Board of Trade as non- explosive. Accumulators (the number and capacity of which naturally vary according to the period over which unattended operation is required) are connected by pipes of special construction to a distributing pillar, at which point a pressure indicator and main gas cock are placed. From here a main supply pipe is run directly to the pressure regulator in the lantern house, the object of which is to reduce the high pressure of the gas from the cylinders to the lower constant pressure required for the opera- tion of the light. From the regulator, gas is led to the mixer (Fig. 5), where it is admitted at A, passes through a filter, B, and enters the gas- chamber C, through the inlet valve D. Here the pressure of the gas forces the diaphragm E of the gas-chamber upward, and with it the pump dia- phragm F, compressing the spring G, and admitting air into the pump-chamber K, through the air valve L. When the diaphragm has reached the end of its up-stroke, the mechanism contained in the gas- chamber C closes the inlet valve D, and opens the outlet valve H, allowing the gas to escape through the pipe I, into the pump-chamber K. With the pressure against the diaphragm F thereby re- lieved, the spring G effects the downward stroke and forces the mixture of air and gas through the discharge valve M into the equaliser O. The object of the equaliser is to maintain the supply of gas during the upstroke of the pump diaphragm. From the equaliser O the gas flows through a regulating valve, P, into the regulator, where the diaphragm Q and spring R maintain a constant pressure. From the regulator the gas is finally led through the fuse valve S direct to the burner. The incandescent acetylene burner employed in this installation is of the inverted type, i.e., the flame is directed downward, whereby a better luminous efficiency is obtained than with the upright type. Another advantage of the inverted burner is that the mantle can be more firmly secured, which is of great importance with regard to durability. These mantles are made of special silk, and are of a tough and elastic nature, but •under the best conditions the life of an in- candescent mantle can never be exactly predicted, and to avoid total extinction of the light from this cause, an auto- matic mantle replacement device is fitted. This particular unit is equipped with four mantles, three being held in reserve, but it is understood that a battery of as many as APRIL 21, 1921 unattended period of twelve months or more can safely be relied upon. Upon reference to the diagram (Fig. 6), it will be observed that the device is actuated by a spring motor, A, which requires rewinding only upon the whole magazine of mantles having been used. The four vertical rods each carry a holder for a mantle, and are so arranged as to rest on the periphery of the revolv- ing rack B, on which is a cam, C. It will be seen that as this rack revolves each mantle carrier in succession mounts the cam, and in doing so causes the vertical rod to move up and inwards until the mantle ring, at the top extremity of the rod, abuts against the burner stem D, thereby checking any further vertical movement of the mantle carrier. As the latter, at this point, is not quite at the top of the cam, the rack also ceases to revolve. The mantle is then " burnt off " by the gas flame, and remains in service till it becomes defective. Upon the mantle breaking, the gas flame impinges upon a small fusible catch, E, which when burnt through allows the mantle fitting to " slip " on the rod, with the result that the pressure upon the cam C is removed, and the carrier in service passes over the top of the cam, and the operation is repeated by the next mantle for service. The small pilot burner by which the main flame is ignited is not in this instance fed by aspecial pipe, but the main burner is utilised for this purpose, insuch a way as to ensureoperation. For purposes of automati- cally extinguishing the light at r IG. 7. sunrise, and lighting it at the approach of darkness, the sun- valve is used. This valve, shown in Fig. 7, is actuated entirely Fig. 6. Sketch of the mantle-changing device of the automatic aerial lighthouse. Fig. 7. The " Sun-Valve " of the automatic aerial lighthouse, which lights the burner when darkness approaches, and turns it out as soon as daylight comes. by light, and is not influenced by changes of temperature. Its construction is based on the well-known physical law that absorbed light is transformed into heat. It consists of a system of metal rods protected by a strong glass cylinder. - j j __ The central rod A is coated with lamp-black, which gives twelve mantles can be supplied. The average life of a mantle it the property of absorbing light, while the three rods B is stated to be from two to three months, and therefore an surrounding it are polished, and thus reflect the light. v
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
