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Discrete Zero Headspace Sampler

Home » Discrete Zero Headspace Sampler

Discrete Zero Headspace Sampler Solinst Model 425T

Discrete interval sampling is ideal for obtaining truly representative water samples from below floating product layers (LNAPL) and for obtaining samples of product itself (LNAPL and DNAPL). It is also used to profile open bodies of water, open boreholes and screened wells, and to collect samples from distinct levels or points of inflow. There is negligible disturbance as can be caused by pumping and purging. Mixing of water from different levels in the well is minimized.

Product Description

Model 425-T
Sampler/Transportation Vessel
This model is designed to prevent any air contact with the sample all the way to the
laboratory, thus retaining all volatiles at down-hole conditions during sampling and during transportation.

The Model 425-T sampler operates in a similar manner to the standard Model 425, but when the sampler is brought under pressure to the surface, the special shut-off valves are closed before the sampler is disconnected from the tubing. Thus air contact with the sample is avoided and the sample is sealed within the sampler with zero headspace, in down-hole condition.

The sampler may then be sent to the laboratory for analysis, without discharging it. The VOCs in the sample will be held in the down-hole state until opened in the laboratory, thus ensuring the highest sample quality at the time of analysis.

Discrete Interval Sampler Capacity

Size Capacity Size Capacity
25.4 mm x 610 mm 175 ml
42 mm x 610 mm 475 ml
50.8 mm x 610 mm 800 ml
25.4 mm x 1220 mm 365 ml
42 mm x 1220 mm 1000 ml
50.8 mm x 1220 mm 1800 ml

Other diameters and lengths available, on request.

Operating Pressure = (Sample depth in feet x 0.43) + 10 psi(Sample depth in m x 9.8) + 70 kPa

Materials
Samplers are constructed of stainless steel with Viton o-rings,Teflon and polypropylene check balls.

Tubing most commonly used is low density polyethylene(LDPE), however, Teflon or Teflon-lined polyethylene tubing is also available. Depth markers may be ordered for the tubing in either feet or meters, as an optional extra.

Operation
The sampler is pressurized using a high pressure hand pump before being lowered into the well to prevent water flowing into the sampler on the way down the well. 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 checkball inside the 1.66" sampler prevents water from entering the tubing, thus avoiding the need to decontaminate 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 ideal for groundwater sampling from below an oil/product layer on the surface of the water, as it allows a sample to be obtained which is untouched by the oil.

The sampler is easily disassembled for decontamination.

Benifits
Purging and disposal of purged water can be avoided.
Sampling directly from a specific depth results in the collection of water which is most representative of the groundwater outside of the well at that depth.

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 loss of volatile organics. The sample has minimal contact with air.

Discrete Interval Sampler Applications
Obtaining a representative groundwater sample from below oil/product layers
Discrete interval sampling in lakes, rivers and wells
Chemical profiling of wells
Sampling at points of inflow to well
LNAPL and DNAPL sampling

Advantages
High quality samples
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

Disposable high density polyethylene bailers and stainless steel Point-Source Bailers are
also available from Envco.