The Inline Sampling Head is housed in a light-tight, dust-proof metal container. This report describes a series of laboratory tests conducted on the prototype Inline Sampling Head for the Eberline Alpha 6 continuous air monitor. The electronic assembly is encapsulated in epoxy resin for protection and housed in a tubular stainless steel case fitted with a pocket clip. Feedback through two transistor emitter followers increases the rate of the oscillator in proportion to Geiger tube current, and a fourth transistor amplities this tone into a hearing aid earphone with resonant air column. Generation of 500 volts to operate the counter is done by a transistor blocking oscillator, transformer, and semiconductor diode voltage quadrupler. The instrument uses a miniature halogen filled Geiger counter as the radiation detector. Operation for one month is obtained from a four volt mercury battery. To insure continious protection, there is no on-off switch. In either range the maximum indications do not block in overloading radiation fields short of that which would damage the components. An optional more » less sensitive range extends the upper limit of proportional indication to 200 r/hr. The proportional range of indication extends from background to about 2 r/hr for instruments set to the normal range of sensitivity. The repetition rate of the chirp and flash is proportional to gamma dose rate. Indications are given by the simultaneous flash of a neon lamp and a burst of audible warning tone best described as a chirp. Worn in the pocket of the user, the device provides immediate audible and visual indication of gamma dose rate. « lessĪ Personal Radiation Monitor instrument was developed that weighs 3 1/2 ounces and has the size of an ordinary fountain pen. The PEMCOAL alarm times were sufficiently fast to warn miners before they are exposed to hazardous quantities of CO. The chemical sensor was tested at concentrations of CO from 10 to 1,000 ppm, at temperatures from 5 to 40 C, and with several potential mine gas interferents. A prototype personal miner's CO alarm called PEMCOAL unit is small enough to be carried on a miner's belt, has a flash lamp visual alarm, requires no calibration for use, and uses a chemical sensor that changes color by reaction with trace quantities of CO. If each miner carried a personal CO alarm, which would respond to high concentrations of CO, the miner would then be alerted when to do either the FSR or SCSR and exit the mine. In many situations, miners do not know when to do either rescuer since they do not know if there is a fire in the mine nor do they carry instrumentation necessary for the detection of the toxic, more » colorless, and odorless fire product CO. In addition, every underground miner must have a self-contained self-rescuer (SCSR) near the worksite that will supply breathing oxygen. Every underground miner is required to carry a filter self-rescuer (FSR), which when operated will remove CO from the miner's breathing air. Underground miners may be exposed to hazardous quantities of toxic gases, such as carbon monoxide (CO), generated from mine fires or explosions.
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