Personal sampling pump

“ Sampler: 37-mm diameter PTFE membrane filter, 1-μm pore size, and cellulose backup pad in two-piece filter holder held together with tape or shrinkable band. Personal sampling pump, 1 to 4 L/min, with flexible connecting tubing. ”

“ Since industrial hygiene analytical methods are geared toward measuring personal exposure, the size, weight, and convenience of the sampler are important elements in sampler design. The personal sampler should allow freedom of movement and should be unobtrusive, unbreakable, and not prone to leakage. The pressure drop across the sampler should not be so great as to limit sample collection times to 10 h with personal sampling pumps. ”

“ The sampling pump used to collect the sample must also be compatible with the sampling needs and the media used. Specifically, the pump must be capable of maintaining the desired flow rate over the time period needed using the sampling media specified. Some pumps may not be able to handle the large pressure drop of the media. This will be true for fine mesh (smaller than 40 mesh) solid sorbent tubes, small pore size filters or when attempting to take a short-term sample on a sorbent tube of a higher than normal pressure drop at a flow rate of 1 L/min or greater. ”

“ This person or group should periodically inspect and repair all equipment and keep track of the use and location of sampling equipment when it is signed out. Sampling pumps should be calibrated with each use. ”

“ Check the pump during sampling to determine that the flow rate has not changed. If sampling problems preclude the accurate measurement of air volume, discard the sample. Take two to four replicate samples for quality control for each set of field samples.
(6) Record pertinent sampling data including location of sample, times of beginning and end of sampling, initial and final air temperatures, relative humidity and atmospheric pressure or elevation above sea level. ”

“ For example, although pumping water with compressed air is mechanically the most inefficient of Page 126 devices, it often becomes the most advantageous, because compressed air may be of necessity laid on for other purposes, and the extra power required to operate a small pump may be thus most cheaply provided. ”

“ It is apparent, therefore, that a pumping machine is wanted which will work continuously without attention, and will not waste money when there is nothing to pump. There are two sources of power in nature which might be harnessed to give this result—water and wind. ”

“ Every village pump is an apparatus for such experiments. In thousands of instances, moreover, pumps have refused to work; but on examination it has infallibly been found that the well was dry, that the pump required priming, or that some other defect in the apparatus accounted for the anomalous action. In every case of the kind the skill of the pump-maker has been found to be the true remedy. In no case has the pressure of the atmosphere ceased; constancy, as regards the lifting of pump-water, has been hitherto the demonstrated rule of nature. ”

“ Experience shows that duplex pumps are more certain of starting after long disuse. The whole power of the main cylinder is available for moving a corroded valve or valve rod, whereas on a single pump with a “steam-thrown” valve no such surplus of power is available.
Further, the direct acting duplex has the great advantage over a fly-wheel pump of not suffering breakage if water gets into steam cylinder. ”

“ The use of compressed air has become very general through the use of small hand pumps; the cylinder of these must be smooth, and the plunger is usually packed with a cup leather packing.
Fig. 340.—Gas Fitter’s Proving Pump.
Fig. 340 shows a gas fitter’s air proving pump. The gauge is attached to any opening into the system of pipes to be tested, with a rubber hose leading to the pump. By working the pump the air is forced into the pipes; upon stopping the pump if the hand upon the gauge remains stationary there are no leaks in the system. ”

“ The cases which receive these cams are engine lathe turned and bored and so true and smooth that the cams when in operation create almost a perfect vacuum and will “pick up” water for a long distance and hold it efficiently. The cams are carefully and accurately planed to mesh into each other to fit their case.
It is a point worth noting that if a little good oil be put into the case of these pumps before and after using at first, or simply to pump air with the oil a few times, the cams become as hard upon the surface as tempered steel, and are almost unaffected by long use afterwards. ”

“ Next to light, the most important creature comfort is water and plenty of it. The most common causes of failure lie with the pump itself. If one of the deep well type gets out of adjustment, repairing it is a professional job and unless you are unusually expert, don't attempt it. Telephone for a plumber or handy man. But with the shallow well pump, you can, in a pinch, replace the leathers that make the valves exert the proper suction. ”

“ Flow rates should be based on accurately calibrated sampling pumps or critical orifices. The amount of analyte collected at the lowest flow rate and shortest sampling time should be greater than the limit of quantitation of the method. The generated concentration used for capacity determination should be at least 2 times the highest published exposure limit and verified by an independent method. ”

“ It is due very largely to the numerous designs of steam valves, that difficulty has been encountered in managing single-cylinder pumps as successfully as those of the duplex type, the similarity of construction in the latter type, even in minor details, being much more marked.
The successful operation of a pump depends to a great extent upon the intelligence displayed in its management, and an engineer can scarcely hope to obtain quiet and smooth running pumps and freedom from breakdowns and perplexing delays except by a thorough knowledge of the details of construction and operation. ”

“ The speed at which a pump is operated is a matter of more or less importance, according to its widely varying conditions. In all calculations regarding the capacity of a pump the regularity with which it makes its “stroke” is taken into consideration; the uniformity of the supply of water to a boiler is always a subject of anxiety to the attendant. The capacity of a pump is usually determined by its number of strokes in a given time, hence the need of a pump regulator or governor.
Fig. ”

“ Air chambers should be made as long in the neck as convenient, so that the water in passing through the pump barrel to the delivery pipe could not be forced up into the chamber, as, if such be the case, the air in the chamber is soon absorbed by the water.
Belt pumps are more economical than independent steam pumps, because the power they utilize is more nearly the equivalent of the power it takes to drive them, whereas in steam pumps there is a certain amount of steam, and therefore of power, expended in tripping the valves and in filling the clearance spaces in the cylinder. ”

“ A single acting pump is one in which the water enters the pump barrel during one piston or plunger stroke, and is expelled from the pump during the next stroke, hence the action of the suction and of the delivery is intermittent, although the pump is in continuous action. ”