Please consider the following tips when choosing which size sleeve to use in your wells.
It's always best to choose the right size HydraSleeve based on well diameter. For example 4-inch HydraSleeves are the best solution for 4-inch wells. However there are times when it makes sense to use a 2-inch HydraSleeve in a 4-inch well. When you need less sample volume than our 4-inch HydraSleeve holds, you may want to choose a 2-inch HydraSleeve. It's an economical option, but there are some things that should be considered before outfitting the 4-inch wells with the 2-inch HydraSleeve.
Most importantly the fill rate will be slower. Having a larger annulus of water around the outside of the filling HydraSleeves allows for more water to flow on the outside of the bag (it's not forced inside the HydraSleeve) so you will need a longer saturated screen zone for the HydraSleeve to fill.
In addition to the instructions below we have introduced 2 new products we call wide-mouth adapters. Information on these useful options can be found here: Wide Mouth HydraSleeve Adapters
For those of you not choosing a wide-mouth adapter a spring clip is required, because it will help maximize the fill rate. Also, we would strongly recommend oscillating the HydraSleeve within the screen zone as described in the rapid, short cycle retrieval method from the HydraSleeve Field Manual:
This will ensure that the HydraSleeve is full and the check valve is closed when you pull it up through subsequent zones and stagnant water at the top of the well.
Do not use a top weight if it was not designed for the specific diameter of the well. For example, you should not use a standard 2-inch HydraSleeve with the 16-ounce top weight in a 4-inch well. It won't compress correctly. While the top weight will reach the bottom, the sleeve will likely be forced along the side of the weight and could cause things to tangle on retrieval.
So, the best option would be to use a 4-inch HydraSleeve for your 4-inch wells. The HydraSleeve can be shortened to collect less sample volume if that is the only reason for using a smaller sleeve. We can customize the 4-inch HydraSleeves for an additional $10 per sleeve. Alternatively the HydraSleeve can easily be shortened in the field following these steps:
1. Tie a knot at the desired length. The 4-inch HydraSleeves holds ~80mls per inch.
2. Leaving a 1-inch tail, cut off the excess below the knot.
3. Using a hole-punch place a hole in the center of the tail for the weight attachment point.
If you have any questions, please give us a call.