Discrete Interval Samplers

Overview

The NEW 425-D Deep Sampling Discrete Interval Sampler can sample from submerged depths as much as 1200 m (4000 ft). The stainless steel sampler connects to the same convenient tubing reel as the standard 425. Operation follows the basic principles of hydraulics. The sealed sampler is pressurized at depth allowing water to enter. The sampler is vented and sealed before retrieval to surface, maintaining sample integrity.

• Representative water samples to submerged depths of up to 1200 m (4000 ft)
• No compressor needed, use a simple bike pump
• Ideal for deep water sampling of boreholes, wells, lakes, and oceans
• Perfect for applications similar to deep abandoned mine shaft monitoring
• Simple to use and to decontaminate

The Model 425 Discrete Interval Sampler is a stainless steel groundwater sampler, with LDPE tubing mounted on a convenient reel. Discrete interval sampling is ideal for obtaining truly representative groundwater samples from below floating product layers, or for obtaining samples of the product itself. The Discrete Interval Sampler can also be used to profile open bodies of water, boreholes, and to collect samples from distinct levels or points of inflow. The Discrete Interval Sampler is a passive sampler that is pressurized when lowered and upon retrieval, to prevent water mixing at different levels. Designed to give zero purge samples.

• High quality, discrete zone samples
• Profile wells or open bodies of water
• Easy operation and transportation
• No mixing of water from different levels
• Avoids purging and disposal of purged water

---

Discrete Interval Sampling

The Solinst Model 425 Discrete Interval Sampler (DIS) is a stainless steel sampler, with LDPE tubing mounted on the 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 Discrete Interval Sampler.

Solinst also offers the Model 425-D Deep Sampling Discrete Interval Sampler for obtaining samples from submerged depths as much as 1200 m (4000 ft).

Operation

The 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 checkball inside the 1.66"ø (42 mm) and 1"ø (25 mm)samplers 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 easily disassembled for decontamination.

Discrete Interval No-Purge Sampling

Discrete interval sampling is ideal for obtaining truly representative water samples and for obtaining samples of product (LNAPL and DNAPL). The DIS 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.

Discrete Interval Sampling 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. Mixing of water from different levels in the well is minimized.

The Model 425 Discrete Interval sampler is 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 quality groundwater samples.

These sampling methods are based on the principle that groundwater which flows into a well, maintains equilibrium with the adjacent water bearing unit. Sampling at the discrete interval should result in representative samples, without the need for purging.

---

Applications and Advantages

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
• Less cost and time to retrieve samples
• Easy operation and transportation

---

Standard Discrete Interval Sampler Operation

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.

---

Deep Sampling DIS Operating Principles

To overcome buoyancy, weights are connected to the top of the Deep Sampling Discrete Interval Sampler before lowering. After the first 100 m (300 ft), one 2 kg weight is added for every additional 100 m (300 ft) of submerged depth.

Once the sampler reaches the desired sampling depth, it is pressurized. Using the basic principles of hydraulics, the pressure acts on the top of a piston (larger surface area) inside the sampler, overcoming the hydrostatic pressure acting on the bottom of the piston (smaller surface area) to allow sample water to enter.

As sample water fills the sampler, air from the sampler is vented through holes (covered with a Vyon filter) on the side of the sampler, which are also opened with the applied pressure.

After the sample is collected, the pressure is released, allowing the piston to reseal at the bottom of the sampler. The sealed sampler is then retrieved to surface, maintaining chemical stability of the sample.

At surface, the sample is collected by reapplying pressure to the Discrete Interval Sampler. The flow of the sample is regulated by the amount of pressure applied. The sampler is easily disassembled for decontamination.