A HydraSleeve captures a discrete groundwater sample by being pulled upward through the target interval — no pump, no purge water, and no power source required. This guide covers how the no-purge mechanism works, which HydraSleeve size fits a 2-inch versus 4-inch well, and when it beats a bladder or peristaltic pump for the job.
How Does a HydraSleeve No-Purge Sampler Work?
A HydraSleeve is a collapsed, closed sampling sleeve lowered on a dedicated line to below the target sampling depth, where it's left to equilibrate with no purging. The sample is captured on retrieval, not while it sits in the well.
Fill and seal sequence
- Lower and equilibrate: the empty, closed sleeve is lowered on its own line to just below the target interval and left to settle.
- Sharp upward pull: the sleeve is pulled up through the target zone in one continuous motion — the upward travel opens a one-way check valve at the base.
- Fill and reseal: water enters through the open valve as the sleeve travels upward, capturing a discrete-interval grab sample; the valve reseals once the sleeve stops moving, trapping the sample inside.
Per ASTM D4448, the Standard Guide for Sampling Groundwater Monitoring Wells, passive grab devices like this sit alongside bailers and dedicated pumps as recognized methods for collecting a representative discrete-interval sample — the mechanism differs from the low-flow purge-and-stabilize approach described in EPA's Low-Flow (Minimal Drawdown) Ground-Water Sampling Procedures, but both are standard references for the same underlying goal: a sample that represents the formation, not the well casing.
How Does a HydraSleeve Compare to a Bladder Pump or Peristaltic Pump?
A HydraSleeve fills passively on retrieval with zero purge water; ERE's bladder pump and peristaltic pump guides both cover active, purge-based methods. Here's how the three stack up on the factors that decide which one you need:
| Method | Mechanism | Purge water | Power/gas needed? | Best for |
|---|---|---|---|---|
| HydraSleeve | Passive grab — check valve opens on upward retrieval | None | No | Low-yield/slow-recharge wells, discrete-interval profiling, IDW-cost-sensitive sites |
| Peristaltic | Suction (vacuum) lift through tubing | Minimal, low-flow | Electric pump | Shallow wells (~26–33 ft), general chemistry, metals, nutrients |
| Bladder | Pneumatic — gas squeezes an internal bladder | Minimal, low-flow | Compressed air or nitrogen | Deep wells, VOC/PFAS regulatory low-flow compliance |
The trade-off is throughput: a HydraSleeve captures one discrete grab per deployment, while a bladder or peristaltic pump can sustain a continuous low-flow stream for parameter stabilization. On a well that recharges too slowly to sustain any pump's flow rate, the HydraSleeve's no-flow-required design is often the only method that works without going dry.
Which HydraSleeve Size Fits Your Well?
ERE stocks HydraSleeve sizes for 2-inch and 4-inch monitoring wells through the HydraSleeves collection, each matched to a specific well diameter and application.
| Product | Well size | Dimensions | Notes |
|---|---|---|---|
| Standard HydraSleeve for 2" Wells | 2" wells | 1.5" D × 30" L (600 mL) or 1.5" D × 38" L (1000 mL) | Standard or Armoured body; top/bottom spring clips and weights sold to match |
| Standard HydraSleeve for 4" Wells | 4" wells | 2.9" O.D. × 37" L | Wider-diameter monitoring wells that won't take the 2" body |
| SuperSleeves | 2" Sch 80 & larger wells | 1.75" O.D. × 31" L | Requires a 1.7" or 1.9" two-piece top collar and bottom weight, sold separately |
The Armoured variant of the 2" Standard HydraSleeve adds a protective outer layer for rough or rocky boreholes where a plain polyethylene sleeve risks tearing on the way down.
How Do You Deploy a HydraSleeve for Sampling?
- Confirm well diameter and select the matching sleeve — the 2" Standard HydraSleeve, the 4" Standard HydraSleeve, or SuperSleeves with a top collar for 2" Schedule 80+ wells.
- Attach the top and bottom weights/clips specified for that sleeve size before lowering.
- Lower the closed sleeve on its dedicated line to just below the target sampling interval and let it equilibrate — no purging.
- Pull the sleeve sharply upward through the target interval in one continuous motion; the one-way check valve opens and the sleeve fills as it travels.
- Retrieve the sleeve and confirm the valve has resealed, trapping the discrete-interval sample inside.
- Decant the sample into bottles through the discharge port, minimizing handling and aeration.
For the broader equipment picture on an environmental sampling program, see ERE's environmental sampling equipment guide and groundwater bailers guide for the other no-power grab-sampling option.
Need help specifying a HydraSleeve for your well?
ERE Inc. has supplied environmental and groundwater monitoring equipment to Canadian consultants for 30+ years — tell us your well diameter and sampling program and we'll recommend the right sleeve.
→ Request a Quote | 1-888-287-EREC | Browse HydraSleeves | sales@ereinc.com
Frequently Asked Questions
What makes a HydraSleeve a "no-purge" sampler?
A HydraSleeve captures a discrete-interval grab sample as it's pulled upward through the target zone — no water is pumped out and discarded beforehand, unlike bladder or peristaltic pumps, which purge before sampling.
Which HydraSleeve size do I need for a 2-inch well vs. a 4-inch well?
2-inch wells use the Standard HydraSleeve for 2" Wells (1.5" D, available in 600 mL or 1000 mL); 4-inch wells use the wider Standard HydraSleeve for 4" Wells (2.9" O.D. × 37" L). 2-inch Schedule 80 or larger wells can also use SuperSleeves with a top collar.
Does a HydraSleeve work in a low-yield or slow-recharge well?
Yes — because it captures a grab sample rather than requiring sustained flow, a HydraSleeve is one of the few methods that works reliably in low-yield wells where a pump can't maintain a stable purge rate.
Is HydraSleeve sampling recognized by ASTM or EPA guidance?
Yes. Passive grab devices like the HydraSleeve fall under the discrete/grab sampling methods described in ASTM D4448, the Standard Guide for Sampling Groundwater Monitoring Wells, and are referenced alongside low-flow methods in EPA groundwater sampling guidance as an option for wells where active purging is impractical.
Related articles
- Bladder Pumps for Groundwater Sampling: A Selection Guide for Canada
- Low-Flow Groundwater Sampling: Peristaltic Pump Selection Guide for Canada
- Groundwater Bailers: Types, Materials & Selection Guide
- Environmental Sampling Equipment Guide for Canada
Lire en français : Échantillonneurs HydraSleeve sans purge : comment ça fonctionne et guide de choix