Power factor improvement capacitors are used in almost every efficiently operated dis tribution system These capacitors usually have an internal discharge resistor to re duce the voltage to 50 volts within 5 min utes after the capacitor is deenergized Nev ertheless, each terminal and the case must be grounded by means of a grounding stack whenever work is to be done on or near the capacitor This ground connection must be maintained until the entire job inspection, maintenance, or cleaning of the capacitor-- has been completed Extreme precaution should be taken when insulation resistance of high-voltage equip ment is tested to make sure that the megohmmeter is not connected into a live cir cuit After it has been determined that the apparatus is completely dead, the free test lead can be attached to an exposed connec tion by use of a switch hook or other type of insulated hot stick Rubber gloves should be worn in case of hand contact with the hanging leads.

Measurements should be taken with the equipment being operated at normal operat ing maximum field size and at maximum current and voltage Scattered radiation should be measured with the work to be radiographed in place Mobile X-ray equipment may be limited m use to a definite room Under these circum stances the same control techniques as for a fixed installation may be used If the unit is used m an unshielded room, distance is the primary control Therefore, such installa tions should be located in areas remote from regions normally occupied This type of installation is safe only if its operation is re stricted by limitations set by a radiation sur vey It is important, therefore, that the radia tion levels be accurately determined for all operating positions of the X-ray tube and orientations of the useful beam In this man ner safe working distances can be determined A movable control booth or bamer may be provided to accommodate all necessary X-ray controls if it is necessary for the controls to be located m a high radiation zone The booth of course should have sufficient X-ray shielding Movable barriers should not be depended upon for protection above 100 kv The "danger" or high radiation zone should be fenced or roped off with sufficient posting of signs Visible warning signals, such as flashing electric signs, should be conspicu ously located at points where it is desirable to prevent trespassing by passers-by in un controlled areas Instructions regarding the safe use of equip ment as well as any limitations that must be imposed should be conspicuously posted at the equipment controls operator completely against scattered radia tion In the design, use and maintenance of such installations the following should be considered The movement of objects through the fluoroscopic installation should be by means of conveyor belts, turntables, or other re motely controlled means It should be im possible for the worker to place his hands m the useful beam Removal of foreign or de fective objects from the conveyor, should pref erably be done by remote control Where this operation must be done normally through an access door in the enclosure, an interlock should be provided which would positively prevent the door from being opened when the tube is in operation Transparent protective barriers, such as leaded glass, should be used for viewing the screen When this barrier is removed peri odically for heat treatment or for replacement the machines should not be used Interlock ing switches should be provided to prevent exposure while the bamer is not in place If the screen is viewed indirectly by mirrors or closed circuit television the lead equivalent of the protective window can be less than that required for equivalent protection for a screen which is viewed directly A common source of radiation leakage is through and around the lead glass particularly after the glass has been replaced Where no mirror is used, the useful beam is directed at the operator, and even a small crack in the shielding may cause serious injury Such cracks can usually be detected with a Geiger counter Fluoroscopic installations.

Electrode holders as used for shieldedmetal arc welding (SMAW) are used to con nect the electrode to the welding cable supply ing secondary current Fully insulated hold ers (Fig 34-7) are preferred because there is less likelihood of accidentally striking an arc with such holders, particularly in close quar ters Electrode holders will become hot during welding operations if holders designed for light work are used on heavy weldmg or if connections between the cable and the holder are loose If a holder of the correct size for the elec trode cannot be used, an extra holder should be provided so that one can cool while the other is m use Dipping hot electrode holders in water should be prohibited On light or medium heavy work, where light, extremely flexible cables are used, hold ers may be attached directly to the work lead running to the machine On heavier work, welders generally prefer a short length at tached to the holder, which is more flexible than the mam work lead Properly insulated cables of weight and flexibility which will not inconvenience the welder are available Automatic and semiautomatic welding Arc weldmg may also be done automatically or semiautomatically to increase the speed of weldmg and provide more uniform weld qual ity Machme weldmg is especially efficient for long welds or where a high rate of pro duction is mvolved and the work can be jigged The rate of electrode feed and arc

Anaconda lead Produets Company was than dissolved and Its assets transferred to Inters national Smelting and Refining Company.

Finish Coat--100 lbs. white lead soft paste, 2 2/3 gai. raw linseed oil, 3 pints turpentine, 1 pint liquid arier, total o 1/& gal. paint.

ID WHITE LEAD IN OtL DCY WHITE LEAD OftY |X> LEAD TRADE WHITE UTHARGE W* An VMmIi tar D+mt* Fata* md Vwwtkm tar Northern fta V-fc This announcement occupied afuU page in the nnrspaprr.

I should like to urge (get him to) him to find out about ------amounts of lead in the excreta.

FLASHINGS Simplex Roof Flashings of Cast Lead, Sheet Lead, and Copper or Galvanized Steel with lead calking collar are available for use on all round flue and vent pipes pro truding from the roof. 1267

Forets and Step Faun aril PIONEER WHITE LEAD. .

In th e p re lim in a ry work o f m anufacture o f le a d t e t r a e t h y l sev era l very serious cases of lead poisoning have re s ta te d .

Since these welding converters are subject to abuse and are given little expert attention as compared to ordinary electrical equipment, they should be well protected, both mechan ically and electrically Often the machines are moved about, so convenient primary power receptacles should be provided about the shop or construction operation Plugs and receptacles should meet the requirements of Underwriters Laboratories Inc AC transformers for welding are usually air-cooled The transformers should be built in accordance with the high standards of elec trical construction used on power or distribu tion transformers A typical industnal-rated AC transformertype welding unit should be equipped with a voltage-reducing control which automati cally reduces the open-circuit secondary volt age to 38 volts during idling This reduction of the voltage is delayed two to three sec onds from the instant the arc is broken to prevent interference with normal welding op erations Contact of the electrode to the work automatically restores normal welding volt age Other safety features are (a) circuit breaker, integrally mounted on the unit, for providing thermal overload protection and serving as a convenient disconnect switch, (b) circuit breaker of the automatic type or a fused safety switch mounted on the wall and rated for use with the unit and the power supply circuit, (c) three-conductor power supply cable, one conductor of which is for grounding purposes, between the wall mounted breaker and the unit Large welding machines are usually in stalled as stationary units Since primary line switches are not normally provided as part of the equipment, they should be installed by the person making the installation The smaller machines, which may be used as portable units, customarily have primary switches built into them and are provided with primary cables and attachment plugs of proper capacity Welding transformers should not be attached to lighting circuits under any circumstance If a gasoline-powered welding generator is used inside a building or in a confined area, the engine exhaust should lead to the outside atmosphere Otherwise, carbon monoxide and other toxic gases may accumulate Voltages The voltage across the welding arc vanes from 15 to 40 volts, depending on the type and size of electrode use The welding circuit must supply somewhat higher voltage to stnke the arc This voltage is called the open cir cuit or "no load" voltage After the arc is established, the open circuit voltage drops to a value about equal to the arc voltage plus the lead voltage drop The open circuit volt ages on DC welding machines should be less than 100 volts Constant voltage power sup plies (welder or converter) are now also being widely used For AC transformer welding machines, ANSI Z49 1, Safety m Welding and Cutting, prescnbes a maximum open circuit voltage of 80 volts on manuals, 100 volts on automatics Some standard heavy duty industrial AC welding machines have open circuit voltages of 65 volts Reliable control equipment is available which automatically reduces^ the open circuit voltage to about 30 volts during the "off" arc period, at which time the welder may be exposed to the open circuit voltage This control equipment is commonly used where welders are working outdoors on wet steel or in confined quarters or under other severe conditions where the probability of con tact with the open circuit voltage may be greater Heavy duty AC welding machines (ratings usually over 500 amp for automatic machine welding) are also built with open circuit voltages of 75 to 80 volts with a special tap to provide 100 volts where necessary The tap may be needed to obtain rated output from the machine if the line voltage is low or if the voltage of the secondary circuit drops The tap should not be accessible to the welder for current adjustment but should be under the control of a responsible electrician or supervisor Open circuit voltages should be as low as 50 volts on small AC welding machines used without expert supervision Since these ma chines are often used with low arc voltage electrodes and with leads not more than 20 ft long, the probability of a large voltage drop m the welding circuit is small For other manual and automatic welding and cutting processes in which the work 961

., 1 the articles on normal Lead of Journal of Industrial Hygiene, September 1035, and L the first part -only) of your articles entitled "-n Appraisal of lbe Lead hazards m>-,'Oc ck o ... i.

Usslgnoro, Constniotloa) a,b,s,d,o,f w l 1 ft - Bed Lead Technical Utter Mo. 3 g - Metal Protective Red Lead Paints b* 1 ' ft *

ByXATrSE.BlHZS WnnlMtWiAr Vinyl chloride has been found i a ; sewer line leading from the S.

Lead In spite of strict employee protection measures in force where lead compounds are processed, hazardous dust is generated when com ponents are moved.