Vacuum sampler

Several other types of hand-held vacuum samplers have been used to collect dust from residential surfaces. One of these, the Baltimore Repair and Maintenance Study Cyclone Sampler (BRMCS) (Farfel et al 1994), has been evaluated against the HVFS. The BRMCS uses the same cyclone and catch bottle assembly as the HVS3, but a different nozzle and vacuum source. The vacuumed dust is sucked into the cyclone via a semi-rigid Tygon hose (2.54-cm o.d.) that is notched on the sampling end to simulate a nozzle. Suction is provided by a small, hand-held vacuum device (Royal Hand Vac , Model 553, 2 A). The collection efficiency for the BRMCS was determined to be 44.1 % n =6, s = 3.8) for plush uylou carpet, 61.1 % (n = 6, = 6.7) for level loop carpeting, 71.8-87.8 % n =6, s = 3.5) for upholstery and 84.7 % n = 3, s = 2.3) for wood surfaces (USEPA, 1996b). 

Rapid sorting of samples from traps or vacuum samplers (ATI can provide identification to order, family or genus to aid parataxonomists in sorting). 

The end or front of the plasma flame impinges onto a metal plate (the cone or sampler or sampling cone), which has a small hole in its center (Figure 14.2). The region on the other side of the cone from the flame is under vacuum, so the ions and neutrals passing from the atmospheric-pressure hot flame into a vacuum space are accelerated to supersonic speeds and cooled as rapid expansion occurs. A supersonic jet of gas passes toward a second metal plate (the skimmer) containing a hole smaller than the one in the sampler, where ions pass into the mass analyzer. The sampler and skimmer form an interface between the plasma flame and the mass analyzer. A light... 

It is often important to quantify the contamination of pore fluid in the unsaturated soil 2one, where monitoring wells are ineffective. In this region, suction cup lysimeters are useful (7). These samplers consist of a porous cup, typically ceramic, having two access tubes which are usually Teflon. One access tube provides a pressure-vacuum, the other discharges the sampled fluid to the surface. The porous cup, typically between 2 and 5 cm in diameter, is attached to a PVC sample accumulation chamber. 

For low pressure pipelines that have ports open to the atmosphere, eg, sewers or closed effluent culverts, samplers are designed to sample through manholes. In a typical system, the Hquid is lifted through a suction line into the sampling chamber under vacuum. When filled, the vacuum shuts off, and the sample drains into a sample jar. A secondary float prevents any Hquid from reaching the vacuum pump. The suction line then drains by gravity back to the source. 

A nonproportional sampler is suitable for near-constant flow conditions. The sample is simply drawn from the waste stream at a constant flow rate. Sampling lines should be as short as possible and free from sharp bends, which can lead to particle deposition. Proportional samplers are designed to collect either definite volumes at irregular time intervals or variable volumes at equal time intervals. Both types depend on flow rate. Examples of some of these are the vacuum and chain-driven wastewater samplers. Other types, which have cups mounted on motor driven wheels, vacuum suction samplers, and peristaltic pump samplers, are also available (26,27). 

Various types of detector tubes have been devised. The NIOSH standard number S-311 employs a tube filled with 420—840 p.m (20/40 mesh) activated charcoal. A known volume of air is passed through the tube by either a handheld or vacuum pump. Carbon disulfide is used as the desorbing solvent and the solution is then analyzed by gc using a flame-ionization detector (88). Other adsorbents such as siUca gel and desorbents such as acetone have been employed. Passive (diffuse samplers) have also been developed. Passive samplers are useful for determining the time-weighted average (TWA) concentration of benzene vapor (89). Passive dosimeters allow permeation or diffusion-controlled mass transport across a membrane or adsorbent bed, ie, activated charcoal. The activated charcoal is removed, extracted with solvent, and analyzed by gc. Passive dosimeters with instant readout capabiUty have also been devised (85). 

Soilmoisture Equipment Corp., Operating Instructions for the Pressure-Vacuum Soil Water Sampler, Soilmoisture Equipment Corp., Santa Barbara, CA (1997). 

OSHA versatile sampler (OVS) sorbent mbes (SKC, Inc., Cat. No. 226-30-16) Teflon vacuum pump (Analytichem International, N726.3FT.18)... 

Manometer (J) Gas-flow meter ( Vacuum pump 9 Gas-sampler Heated tube... 

Porous cups can be used as probes in the monolith and suction can be applied to them to move water out of the soil and into a sample container under unsaturated conditions. Passive samplers that do not involve pressure or vacuum are also available [11]. 

All filtering and extraction systems must be checked for compatibility with the analyte of interest. Some or all of the analytes may be absorbed or otherwise lost during the extraction process, and this must be known beforehand. Carbon may be lost by high vacuum differentials between sampler and soil water. Long extraction times may lead to distortions in the results of the sample analysis [5],... 

A high volume Staplex air sampler with a vacuum capacity of 24 L/mln was placed horizontally on top of the berm facing towards the bed and operated for 2 hr. The air sampling procedure Including the preparation of the resin and extracting the captured pesticide vapors has been reported by Wehner et al. (3). 

Access the membrane by connecting the MSOpener to a vacuum source, and placing the MicropreSure in-line hltration sampler on top of the MSOpener. 

Figure 14 shows the altitude effect on the sampler flow rate. This test was performed in a vacuum chamber. The flow rate was monitored with a bubble tube which was mounted in the chamber and operated by remote control. Each data point is an average of 18 pieces of data three samplers and three flow rates which were monitored while both increasing and decreasing the vacuum. 

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