Suction sampling device

The revised suction sampling device was tested by comparison with the previous device. Results are presented in Table 25.5. This represents a good recovery of NG when compared to Table 25.4 and illustrates that the device is effective. However, in this instance only one membrane filter was present in the suction line consequently, like is not being compared with like. The improved recovery may be due to a combination of factors. 

Clothing is sampled by suction using the revised suction sampling device (see Figure 25.2). Samples taken are stored at -20°C until required. The Del-drins are reusable and are washed according to the procedure given in reference 219. 

Suction lysimeters are required for some field-scale groundwater monitoring studies to monitor the transport of compounds of interest through the unsaturated zone. Unlike monitoring wells or water supply wells that sample water from the saturated zone, suction lysimeters sample water from the unsaturated zone. This section provides a summary of the installation and sampling procedures for pressure-vacuum suction lysimeters. A detailed discussion of unsaturated zone sampling devices is available elsewhere. 

Portable sampling devices were categorised by Nielsen and Yeates (1985) as grab samplers, suction lift devices and positive displacement mechanisms. A brief review of each category is given below. 

Membrane pumps are the most extensively used suction units commonly included in commercial sampling devices, and they operate with a range of power outputs. Czechoslovak membrane pumps (Chemoprojekt, Prague), Hungarian pumps of the type MIKI G-13 and membrane pumps from companies Hartmann-Braun and Austen are examples of such pumps in general... 

Percent solid settled In tests where adsorption and flocculation were determined simultaneously, the 200 ml sample was allowed to settle for 30 seconds and then 100 ml of the supernatant was removed using a suction device and after centrifugation analyzed for residual polymer concentration. The minimum level of detection was at 0.5 to 1 ppm and the reproducibility of the adsorption measurements was 2-3%. The settled 100 ml portion was analyzed for solid content. Flocculation due to polymer addition is measured by noting % solid settled as a function of polymer concentration. 

Figure 9. Configuration of the DS-IC system A, clean air input B, mass-flow controller C, permeation device chamber D and H, vents E, needle valve-rotameter F, needle valve G, mass-flow meter I, diffusion scrubber Jy scrubber liquid reservoir K, needle valve-rotameter L, suction pump M, injection valve Ny peristaltic pump O, eluent flow F, downstream chromatographic components and Q, sample loop. (Reproduced from reference 96.

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). 

Low-volume air sampler A low-volume air sampler is an apparatus having a suction capacity of up to 201/min. It is used for one continuous sampling lasting from several days to 1 week. Filter papers having a diameter of 5 cm and an active-carbon cartridge can be attached as a collecting device. 

Mostly pesticides in house dust are analyzed from floor dust taken with vacuum cleaners (or other suction devices). Even though there are standard protocols for sampling house dust [84, 90, 91] a great variety in sampling techniques has to be noted. These were reviewed by Butte and Heinzow [85] andMacher [92]. 

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