Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
21 99876
Waterra Disposable Bailer
Liquid Sampling Apparatus
The invention described in this application relates to a device intended to be used for
obtaining a volume of liquid from a liquid reservoir.
Back~round
Obtaining samples from groundwater, which describes underground water sources,
enables geoscientists and regulatory agencies to evaluate the subsurface for the presence
of environmental cont~ in~tion. Environmental groundwater sampling is most
commonly conducted by advancing a borehole into the ground with a drilling rig or such
apparatus and installing a monitoring well. The monitoring well consists of a casing,
typically polyvinyl chloride (PVC) or steel, which is extended into the ground to a depth
beneath the level of standing groundwater. The base of the well casing contains a
screened portion, which enables water to flow into the casing, while keeping thesurrounding soil material out. Samples of representative groundwater from the
monitoring well are then analyzed by a laboratory for parameters defined by regulatory
guidelines and these results are used to determine the extent and level of cont~ n~tion
in the subsurface.
Groundwater sampling is cullelllly conducted by two methods, through pumping systems
or via grab samples conducted by devices called 'bailers'. Bailers are typicallyconstructed of a tubular body of metal or plastic that contains a hole at the bottom of the
tube that is of a smaller diameter than the inside diameter of the tube body. The top of
the device also contains an opening and provides a connection in which a cord or rope
can be attached. A ball, which is a slightly larger diameter than the hole at the base and
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top of the device but is of a size to allow it to move freely within the tube, is placed
inside the bailer.
To obtain a liquid sample, the bailer is lowered with a cord down a monitoring well or
into the surface of liquid to be sampled. The liquid enters into the bailer by the hole at
the base of the device. After filling, the bailer is raised out of the liquid and the ball,
which is constructed of a material denser than water, forms a seal around the base hole
thus preventing the liquid sample from escaping. The sample is then transferred to a
sample container by pouring the liquid out via the hole at the top of the bailer and into
the container.
Of the varieties of bailers currently on the market, they all fall into two categories; non-
disposable or disposable types. Non-disposable bailers are typically constructed of either
stainless steel or Teflon which are non-reactive to most chemical compounds
encountered in the groundwater at cont~min:~tçd sites. They also disassemble forcleaning which is required after every sampling episode. Cleaning bailers is time
consuming, costly and introduces a potential for cross-cont~min~tion between samples if
the cleaning is not done correctly or completely.
An alternative is disposable bailers which are intended for one use only. Disposable
bailers are relatively cheap compared to non-disposable types and are typically
constructed of polymers, including but not limited to polyethylene, polypropylene or
polyvinyl chloride (PVC). Although these materials may not be as chemically inert as
those in non-disposable bailers, the residence time for the cont~min~ted sample in the
bailer is usually only less than a minute, therefore in most cases the chemical compounds
in the sample do not have enough time to significantly react with the plastic in the bailer
prior to transferring the sample to a container. As an added feature, both non-disposable
and disposable types of bailers are offered with weights. Bailer weights typically consist
of a metal torus secured to the bailer wall. This feature makes the device heavier and
decreases the time that the bailers take to fill, hence making sampling more efficient.
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Both disposable and non-disposable bailers have common problems which require
improvement. These problems include having a valve at the base of the bailer which seal
effectively (bailers with balls have difficulty obtaining a complete seal due to either the
non-perfectly spherical nature of the balls or to a seam running around the girth of the
ball due to the molding process in which they are manufactured). Balls are available
without parting line seams from the molding process, but are relatively expensive and
therefore are prohibitive for use in a disposable item if cost effectiveness is to be
observed. The use of a ball can prevent proper seating on the bottom hole of the bailer
and thus leakage can occur. It is understood, however, that total sealing may be difficult
to obtain due to silt or sand particles that may be in the water that prevent a seal around
the inlet hole.
Another negative feature with bailers currently on the market is the non-l-allsparel-l
nature of most plastics or the opaqueness of metals used in bailer manufacture.
Transparency is a feature that is desirable due to its ability to allow one to inspect the
sample visually prior to transferring the sample to a container. Liquids immiscible with
water are also known as free-product, and include oils, gasoline and other lighthydrocarbons. These can be observed in the device as they would appear on the surface
of the groundwater (free product can also include hydrocarbons that are denser than
water but these types are not typically sampled with bailers). Polyethylene and
polypropylene are not ll~nsl)arelll and although lranspalelll PVC and other polymers are
available, they are difficult to extrude to form a tube which is thin enough, cheap enough
and rigid enough for use in a one liter disposable bailer.
A further problem with the design of bailers presently available is the relative locations
of the discharge hole and the connection point where a lowering cord can be attached .
Due to allelllpl~ to simplify manufacture and to space constraints, their proximity to each
other makes it difficult to pour the sample from the bailer without spilling the sample or
encountering interference with the cord.
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Summary of the Invention
The goal of the project which resulted in the development of the Waterra disposable
bailer was to construct a bailer that has a capacity of at least one liter; to contain an
intake valve with components that do not interfere with the pouring spout when
collecting the sample; to be transparent to allow for visual inspection of the sample and
free-product; to have a discharge spout that is not interfered with by the supporting cord
or rope; to be inexpensive; to be weighted for rapid filling; and to have increments on the
body, in both inches and centimetres, allowing for measurement of free product in the
sample.
To meet the above referenced objectives, the Applicant has utilized manufacturing
technologies previously not commonly associated with bailer and bailer componentmanufacture.
In the optimal configuration of the invention, the ball has been elimin~te-l entirely by
l]tili~ing an injection molded valve consisting of three parts: the valve seat, the valve
housing and the valve stem. Injection molding the parts allows for precise quality
control. Alternatively, a precision ground ball can be used instead of the valve stem, but
due to cost constraints, an injection molded part is preferred.
The body of the Waterra disposable bailer is constructed of transparent PVC that is
vacuum formed in two halves, with the parting line offset from the centre along the linear
axis. This manufacturing process allows for the use of strong, rigid and llallsl)alelll PVC
material that would be difficult to produce with extrusions. The two halves are attached
along the seam by Radio Frequency (RF) welding. This technique fuses the plastic parts
together to form a seal without introducing glues or solvents that could con~ te a
groundwater sample. Vacuum molding also allows for h~ lillg increments, without
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the use of inks, along the length of the bailer for free product measurement. This is not
possible with extrusion technology if the bailer is to remain economically priced.
A pouring spout has been molded in a location separate from the connection point where
the cord is tied to the device. The shape of the spout is designed such that the discharge
hole can be readily enlarged to increase the speed in which the bailer can be emptied. A
sample can be obtained without interference from the support cord.
The Waterra disposable bailer has been designed to be weighted to allow rapid filling of
the device. This is accomplished with a PVC plastic, water tight weight compalllllent
that is filled with cast off metal punchings or similar materials with high specific gravity
and weighs one quarter of a pound (114 grams). The weight col..palLlllent is held in
place inside the bailer by two flanges molded into the inside of the vacuum molded body.
The flanges are designed such that liquid is able to pass around the weight compartment
to fill the device. Cast off metal punchings were used to make the weight container cost
effective.
Brief Description of the Drawings
In the drawings which illustrate the embodiment of the invention, Figure 1 is anelevational side and front view of the Applicant's disposable bailer; Figure 2 is an
elevational side and front view of the top end of the Applicant's disposable bailer,
detailing the pour spout, the cord connection location and the RF welded seam; Figure 3
is an elevational side and front view of the bottom end of the Applicant's disposable
bailer, detailing the injection molded weight coll-pallment and the injection molded
valve assembly; Figure 4 is an elevational exploded side view of the injection molded
valve assembly; and Figure 5 is a cross-sectional view of the injection molded weight
colnl)al l-nent, indicating the metal punchings used as weight.
21 99876
Description of the Optimal Embodiment of the Invention
The device illustrated is comprised to two linear vacuum molded halves, an anterior half
1 and posterior half 2. The two halves are joined along a seam 3 along the linear axis by
a Radio Frequency (RF) weld producing a leak-proof seal without the use of adhesives
that could compromise the quality of samples obtained from the device.
A hole 4 is open at the upper distal end of the device which allows for the attachment of
a cord, rope or cable for lowering the bailer into a liquid. A pouring spout 5 is molded
into the anterior half 1 of the device which protrudes away from the face of the half 1. A
hole is open in the center of the spout 5 which allows for the controlled flow and release
of liquid contained in the device. The surface of spout 5 extends perpendicularly from
the face of the anterior half 1 and is then chamfered inwards at an angle which concludes
at the inside diameter of the pouring hole. If a larger diameter pouring hole is desired,
the spout 5 can be cut along the neck of the spout 5 to obtain a larger diameter pouring
hole.
During the vacuum forming process, incrementations in inches and centimeters aredebossed along the faces of the anterior half 1 and posterior half 2, respectively. These
incrementations commence at the lower distal end of the device and conclude at the
upper distal end.
An injection-molded PVC valve assembly comprised of a valve stem 7, a valve housing 8
and a valve seat 9 is set into the lower distal end of the bailer. The valve housing 8 and
the valve seat 9 are snap-fitted together through a hole 12 in lower distal end of the
anterior half 1. The snap fit provides a seal between the anterior half 1 by tightly closing
two flexible collars on the bottom of the valve housing 8 and the top of the valve seat 9.
The valve stem 7 is held in place by the valve housing 8 and the valve seat 9 and is
allowed to open and close through a range of motion limited by the top of the valve
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housing 8 and the top of the valve seat 9. Alternatively, a ball can be used in the place of
the valve stem 7.
An injection-molded PVC weight co--lpa~ ent 10 is secured in place with a flange 11,
located near the lower distal end of the device and which is comprised of two mirrored
parts. One is molded into the anterior half 1 and the other molded into the posterior half
2. Figure 3 illustrates the position of the weight compartment l 0 when the halves of the
bailer are sealed. The weight con.pall-l.ent is secured in place by protuberances at the
top and bottom of the halves of flange 11.
The embodiment of the injection-molded PVC weight con-l)a-l-l~ent 10 is illustrated in
Figure 5 and is comprised of three parts; the weight container body 13, the cap 14 and the
weight material 15. The weight material 15 shown is comprised of cast off metal
punchings. The cap 14 is snap-fitted to the weight container body 13 and the entire
weight conlpa~l-nent 10 is inverted so that when placed in a liquid, an air-lock is formed
and no liquid can enter the weight col..l3a I nlent.
