Document vVZzmXOO7aDrJjdymK40Rq6vq

Controls and Instruments X. Field Control Division of H. D. Conkey & Company, Mendota, M. Manufacturers of FIELD DRAFT CONTROLS FIELD BAROMETRIC DRAFT CONTROLS FIELD M -f- MG2: A THREE-FUEL CONTROL, IN SIZES 10 IN. THROUGH 32 IN., FOR OIL, OIL-GAS, GAS, AND COAL FIRED FURNACES AND BOILERS. The M+MG2 will serve gas, oil or coal with equal efficiency, and requires only minor, in-the-field changes to adjust from one fuel to another. A plant might convert from coal, to oil, to gas, then to oil-gas, without obsoleting this control. With coal it serves as a combination barometric draft control and check damper. With oil it serves as a singleacting barometric control. With gas it becomes a double-acting control, open ing inward to regulate up-drafts, open ing outward to relieve down-drafts. Where gas-oil is used interchangeably, the control change takes less than a minute. The Field M+MG2 is a specialized, precision-made, three-fuel control. Be cause it is a control of extreme sensi tivity, it is, of necessity, a control of extreme structural strength. For ex ample, accuracy is increased when the . clearance between a ring and gate is held to a minimum. To permit this, in the M+MG2, without risk of binding. Field developed a die-formed, heavy gage ring. Its deflection strength exceeds many fold the normal requirements of shipping, installation or use. The gate is also very heavy--39 pounds for a 32 inch control. Such weight obviously provides extreme rigidity. Heavy weight is also, paradoxi cally, a requirement of the virtually 284 Field Control Division friction-free gate mounting that gives the M+MG2 its extreme sensitivity. Only a heavy gate could be so delicately balanced. The same weight factor also prevents the spurious responses to which so sensitive a gate might normally be subject. Controls and Instruments The M+MG2 gate is mounted on a long, thin, stainless steel knife edge, which in turn rests on self-aligning bearings. The bearings are self-cleaning. Soot or dirt cannot accumulate to cause binding or friction. They are also ^elfleveling--assuring that the knife edge is always in contact across the full width of the bearing, for an even distribution of weight. When the gate moves, only the sharp corner of the knife edge rests on the bearings--an area of contact so mi nute that friction is virtually non-existant. The result is extreme and instanta neous sensitivity to draft change. The gate is deeply recessed in the ring, to direct the flow of air over the gate and avoid response to random, variable air conditions outside the control. FIELD TYPE M: For automatic heating equipment, designed to assure finer per formance, greater fuel economy, through highly accurate control of drafts. Avail able in sizes from 6 in. through 9 in. for pipe diameters of 5 in. through 10 in. Features "Rocking Chair" gate action, off-center gate mounting, sidewings, ex tended housing. Widely used in the heat ing industry. FIELD TYPE RC: Calibrated draft con trol in sizes 6 in. through 9 in. for 5 in. through 10 in. flues. Features extreme capacity, and reversible wing flap on gate for more precise adaption to eithei vertical, horizontal or sloping flues. Fric tion-free gate mounting, single strap at taching, easily leveled on a sloping flue. The M+MG2 permits an unusually wide range of draft settings. The 18 in. control, for example, will maintain a draft setting as low as 0.002 in. The same con trol will maintain a draft as high as 0.3 in., a requirement where there is a very high draft loss through the appliance. Compensation for differences between horizontal and vertical installation is fully provided, by the simplest means available on any Field control. Where a safety switch must be specified, to meet gas code requirements, attachment is easily, effectively, and compactly made. Compactness is a characteristic of the M+MG2. There are no protruding parts. Even the stainless steel bead chain is short, holding setting weights neatly against the side of the. control. FIELD MG1: Double-acting control for lower-input gas-fired furnaces and boil ers; widely used in conversion burner installations. Opens outward to relieve down-drafts; opens inward to regulate up-drafts. Sizes 7 and 8 in. for 6 through 8 in. flues. 285