The Solinst Model 425 Discrete Interval Sampler (DIS) is a stainless steel sampler, with LDPE tubing mounted on a convenient Solinst reel.The reel has a pressure attachment for a high pressure hand pump, and a pressure/vent switch which is used to apply and release the pressure on the sampler. A sample release device is included with each standard Discrete Interval Sampler. The Model 425 Discrete Interval Samplers are also recognized as a no-purge sampler. No-purge, also known as zero-purge or passive sampling methods, have gained acceptance by many regulatory agencies worldwide for obtaining high qualitygroundwater samples. The Discrete Interval Sampler is pressurized before being lowered into the well to prevent water flowing into the sampler. Once the desired depth is reached, the pressure is released and hydrostatic pressure fills the sampler with water directly from the sampling zone. A floating check ball inside the samplers prevents water from entering the tubing, thus avoiding the need to decontaminate the interior of the tubing.When the sampler is filled, it can be repressurized and raised to the surface. The sample is decanted using the sample release device, which regulates flow and minimizes degassing of the sample. The sampler is easily disassembled for decontamination. Applications Obtaining a representative groundwater sample from below oil/product layers Discrete interval sampling in lakes, rivers, and wells Chemical profiling of wells A sampling at points of inflow to well LNAPL and DNAPL sampling VOC sampling Discrete interval samplers (DIS) are excellent for VOC sampling. There is no mixing with water from different levels in the well. The sample does not travel through a long length of tubing, risking the loss of volatile organics. The sample has minimal contact with air. LNAPL and DNAPL SamplingThe Solinst Model 122 Interface Meter quickly and easily detects water as well as floating or sinking product layers (LNAPL or DNAPL).Infra-red refraction is used to detect liquids and conductivity to distinguish water. A steady light and tone indicates product. Water is indicated by intermittent signals.Once an LNAPL or DNAPL layer is detected, a sample can be taken using a Discrete Interval Sampler at the depth indicated on the Interface Meter flat tape (marked every mm or 1/100 ft). Advantages High-quality samples The sample has not been pumped through tubing No mixing of water from different levels Minimal disturbance of the water Easy disassembly for decontamination Avoids purging and disposal of purge water Easy operation and transportation Materials Samplers are constructed of stainless steel with o-rings, and PTFE and polypropylene check balls. Tubing most commonly used is low-density polyethylene (LDPE), however, PTFE or PTFE-lined polyethylene tubing is also available.Larger size reels, including Power Reels, are available for holding longer lengths of tubing.
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