8 JANUARY 2024 WorldWide Drilling Resource® How Does a GUS Sampler Work? Adapted from Information by Acker Drill Company The Gregory Undisturbed Sampler, more commonly known as a GUS Sampler, is a unique, air or hydraulic piston sampler designed and proven in the drilling field for many years. The design allows the sampler to be classed as a truly undisturbed piston sampler for high-production sampling. First, the hole is drilled by rotary means and prepared by using either casing or drilling mud to support the overburden. Next, the GUS Sampler is assembled on a drill rod and lowered to the bottom of a cleaned borehole. The drill rods used to extend the sampler to the bottom of the hole may be clamped to the casing to prevent upward movement from down thrust of fluid or air pressure, or rods may be connected to the chucking rod in the rotary drill head. A water swivel is attached with a hose line coupled to the swivel and the pressure pump to direct fluid or air into the drill string to operate the sampler. A positive displacement pump or compressed air is used to exert pressure on the stationary piston of the sampler. As the water or air pressure is applied to the drill rods at approximately 100 to 600 psi, the piston in the head of the assembly forces the thin wall sample tube in the soft underlying soil or clay materials to take the sample. Once the sampler reaches the end of its maximum travel, the water or air used for pressing is exhausted through a relief hole and returned immediately to the surface. This signals the operator that the sample has been taken to its maximum depth. A compressed air bottle or tank may be used instead of a fluid pump for pressing the s a m p l e . However, be careful to limit tank pressure to prevent overpressure which may collapse the sample tube. Depending upon the materials being sampled, the sampling may take only a few seconds or as much as a minute to reach its maximum travel. Once the sample has been taken, the rods and sampler are pulled to the surface and the sampler is laid out on a work table for removing the sample tube containing the sample. The outer tube of the sampler containing the sample is rotated counterclockwise for three turns which releases the vacuum lock created over the sample in the sample tube, allowing the sampling tube to be easily removed from the assembly. A new sample tube is then installed on the sampler head for additional tests and the procedure is repeated. The GUS Sampler is available in four popular sizes - 2½, 3, 3½, and 5 inches. It also uses standard ASTM thin wall steel sampler tubes with standard holes and cap screws. The sampler, with a stainless steel actuating cylinder, adapts directly to standard AW or NW drill rods with maximum sample lengths of 24 inches. ENV Louisiana Ground Water Association 2024 Convention & Trade Show January 9-10, 2024 Paragon Casino Resort Marksville, Louisiana ATTENTION CONTRACTORS - This will be your only opportunity to obtain Education Points for the state of Louisiana. Registration Form Available Online at: https://LGWA.org Discount Code LGJ08GR
RkJQdWJsaXNoZXIy NDk4Mzk=